Raster Processing in Global Mapper

hello everyone and thank you for joining me today for the latest in our global mapper webcast series today's presentation as you can see on the slide in front of you is entitled raster processing in global mapper we tend to focus a lot of our attention on working with vector data so today we've decided to give some attention to raster data to working with raster data very often relegated to the role of a base map raster data it does have a viable role to play in the broader field of geospatial data processing and geospatial analysis so we're gonna introduce some of the components on the elements of global mapper that allow you to work with raster data and allow you to derive intelligence from your raster data files those of you who've been following our recorded broadcasts or are been following some of our live broadcasts may recall those times when we had an open session for questions obviously this is not an option with a recorded session there is no question and answer session in real time but if you do have questions about any of the topics that I cover any of the issues that I raised or just any questions in general you can email us directly Jill helped at Blue Marble geo comm is our contact email I will put that in the description below the YouTube feed if you're watching us on YouTube you'll see that link right in there if you're watching this on our web site you can go to the menu at the top of the screen and go to support and find your way to our support site there so there are communication options that are available to you and I also want to plug the global map or forum if you want to share some of your ideas or engage with some other users or ask questions the global map or forum is an excellent venue for that I will provide links to those sites to the email and to the global mapper forum at the end of today's presentation so for today our primary focus as I said is going to be working with raster data specifically we're going to introduce the basics of processing raster data in global mapper well look at some of the configuration options loading raster data some of the settings you can apply and maybe even introduce what exactly a raster layer is how it differs perhaps from from vector data you may be used to working with we will move into some of the more specific settings things just in transparency in a raster layer talking about the contrast adjustment some of the kind of fine-tuning you can apply when you're working with with raster data or imagery imagery data layers will talk about cropping the idea of physically reducing the size of some imagery to limit it to what you specifically require in a project area and we'll also talk about the tiling process you will find that when working with raster data some of those files can get very large very hard to manage so we'll talk about tiling mobility to manage data in smaller sections and in a sense the opposite of that we'll introduce the idea of mosaicing making is actually a very simple process in global mapper if you bring in multiple files and you run an export whether that be in the same format or whether you want it to convert to it convert it to a different formats global mapper will inherently mosaic those tiles together so mosaicing is part of a normal workflow and global mapper we want to talk about that some of the more advanced processing that can be applied in global mapper will specifically talk about rectification the idea of being able to take a standard image file a picture if you like and use some ground control points to give that geographic intelligence to create a geo-referenced raster layer that again can be exported in any of our supported formats and used in any other geospatial application we will transition a little bit to kind of introducing an element of vector data and that is the ability to derive vectors from a raster layer this is perhaps one of the more hidden functional components of global mapper but at the same time it is one of the more powerful tools some of you have know I've talked to folks who've been using global mapper for quite some time who when asked to find this function are not even aware that it's they're not even aware that's an option so I'm gonna introduce you to the vectorization tool as I like to describe it the ability to derive vectors from a raster layer will also introduce the opposite which is essentially rasterizing vectors which is actually a simple if you want to export a raster file and you have vector features on your screen lines point polygons they will be rasterized when during the export process there is an option when you export to include those vector features so that is a fairly automated process but we will address that in the context of this workflow going back and forward between raster and vector files we will then talk about the raster calculator introduced fairly recently the ability to perform a numeric calculation against some raster data specifically in this scenario we're going to conduct an end DVI and naturalised difference vegetation index analysis essentially what we want to do is is determine the relative greenness of an area and that's going to be derived from multiband imagery we're gonna use some Landsat imagery and perform a calculation on the red band and the near-infrared band that are part of that data set and in order to gauge the relative greenness well actually take that analysis a step further and do a seasonal comparison we're kind of moving away from the fundamentals of raster processing but to complete that workflow we'll use some of our our calculation formulas to conduct the an analysis of the difference between those two seasons so again to complete the workflow we'll we'll do the entire process and to wrap up today we're gonna give some recommendations in terms of best practices for batch processing or indeed for processing raster data in any way when we're dealing with raster file so they tend to be very large per unit of geographic area if you're rendering objects in a raster form the file size when compared to working with the comparable comparable coverage area with vector data is gonna be a lot lot larger so you will want to employ some efficiency mechanisms when it comes to processing raster data whether it be converting reprojected or just manage it when managing that data within the context of your working global mapper so we'll introduce things like grouping data backs processing we have a batch processing application within an application and I will introduce a little bit of scripting I'm not sure I'm gonna have time actually to demonstrate the creation of a script but that your raster data can be processed using a script if you are interested more information on scripting there is a dedicated video that we have on our youtube channel about building a script in global mapper but it is a component of the best practices I guess for processing raster data so the first bullet introduction to raster data in global mapper and we're going to begin by introducing the basics and essentially exploring the some of the components of global mapper that pertains specifically to working with imagery or working with raster layers so the procedure for accessing raster data in global mapper is the same as any other files we have the button in the middle of the introductory screen to open your data you can also go to the file menu drag and drop also works if you want to simply drag an imagery file or a raster file and putting it at the global mapper that way it's very simple as well I'm just going to import a sample of a jp2 file which is a JPEG 2000 file one of the more common file formats you may encounter and this just happens to be our brand new office here this is where we are right now we just the last couple of months move to a new location and this is a raster this is a picture this is an aerial image obviously it's easy with when using this image to discern visible features we can see cars in the parking lot we can see the building itself and we can see vegetation over here to the right side of my image this was a file that I actually accessed from an online source I used a streaming service to access data and I was able to capture that save that locally and one of the questions that we are often asked is where do I get data where is the best location for me to find data well certainly those online sources are very useful very valuable they provide a lot of high quality data sets including a lot of imagery such as you see now and not only for the US but also a worldwide you can also access files you can access imagery in file format many regional government state government provincial government agencies will archive imagery and allow you to download that maybe through some sort of interactive map where you can what areas you're interested in they'll package up those files and allow you to download them and some of the more common formats that you will encounter are including mr. Sid I'm just gonna open up my list here so we can see some of the the raster types mr. Sid is a common one if I scroll down under the MS multi-resolution seamless imagery data database I guess is a common imagery format geo TIFF is another one that is supported and is very commonly used JPEG 2000 was the what the format of the file that I imported spirt my personal preference I like working with jp2 files ECW is another format that's supported so essentially all of the common formats that you're likely to encounter when you access data when somebody sends you a file or when you download some data global mapper can ingest those files also as I mentioned you can access data from a streaming service access a raster data from a streaming service if I open up our online data dialog box the little globe here in the toolbar at the top of my screen is the easiest way to access that function you can see an entire section here if I collapse this window you can see a section that allows us to access imagery and this obviously is just one element of of raster data aerial image will introduce some other examples of raster data in just a few minutes but off the bat here as you can see we've got some Landsat imagery this is actually a redirect to the earth Explorer site where you can download the files themselves this is essentially there's not a streaming service but a data access service but some of these as you can see are streaming services we have the u.s. nape data which is administered by the Department of Agriculture recently introduced to the global mapper setup is the u.s. national map data and you can see as part of that package we have one full resolution data in fact the image you're seeing behind us dialog box was accessed using that service we have a catch-all world imagery set as well you can download it various resolutions depending on where you are in the world but again a streaming service allows you to render the data in real time other email or raster datasets you'll find in here we have a section on topographic maps I will as an in a minute introduce some very Asians on the theme of raster data but we can we can obviously download topographic maps if you're in the US the USGS quad maps are streamable you can download and again process the data so online streaming services are an excellent source for getting raster data now my last bullet if you recall when I introduced it as topic was best practices I'm going to introduce one of those best practices now because it's appropriate in this context if you are streaming data if your intention is to access data from one of those online services and I strongly encourage you to explore those as essentially your own personal data library embedded within global mapper I would strongly encourage you to download whatever areas of interest that you happen to be working in or exploring obviously in my case I initially streamed the imagery of the new building here and after I had to find that and delineate it the extent I downloaded that file so this is now a local file on my hard drive the benefit is obviously I'm not no longer dependent on the streaming service my internet connection I can load up the file a much more quickly so that is a recommended best practice workflow when you're accessing data online is immediately initiate the capture of that data and that process is initiated right from the file menu you'll go to export and choose your raster image format for that process now if you have a specific format that you require to work with and obviously you can choose it from this list if you want a personal recommendation for me I would suggest JPEG 2000 would be the one that it's a good combination of efficient compression and quality of the data and the image you see behind obviously is a JPEG 2000 image so access to data whether it be in file format or whether it be streaming service gives you an opportunity to integrate a lot of different raster files into global mapper now let's take a look at some examples of raster data obvious you can see this is an aerial image this is a I believe a 25 centimeter resolution aerial image now we can prove that we can verify that by simply zooming in obviously at this level it looks like a crisp full Graff but as you'll see as a zoom in it becomes clear that this image this apparent smooth image is actually comprised of a series of what are called pixels each one of these pixels as you can see is a solid color this one is a fairly defined green color we have a lighter kind of beige color I guess or a grayish beige color here at this level the data doesn't seem to be of any value it's not really conveying anything useful um you can see very quickly if you look at my scale bar at the bottom of my screen this is in meters so this is 25 centimeters right here we can verify that that is the resolution of this image every pixel is 25 centimeters apart now does that mean that anything any feature that's smaller than that will not be visible well not necessarily if you have something that's smaller than that that's a particular color the aggregate color within each pixel will be determined by whatever with the majority of that pixel encompasses so even if you have something that's small let's say you have a align feature that's narrower than 25 centimeters chances are the influence of that color within that pixel will determine that it will actually be visible maybe not in a crisp form but you only see a shaded color that represents whatever that feature is now I'm gonna zoom into one of the cars here again as i zoom in you will notice it breaks the image down into array of pixels I at this stage if I asked you want this feature is you couldn't tell me it was a car chances are you just think it's a a array of blocks or a river of individual colors but as you'll see as i zoom out your eye plays a trick on you it starts to merge those together and at this stage you could tell me it's a car you know it's a car because of the context in which it's located it's in the parking lot so it doesn't look like a nice red car here but when you get in close obviously you're starting to see the individual pixels you're not going to get as much value for that data now because of that I'm gonna introduce you to a component in global mapper that you may find to be useful when working with raster data obviously by default there is no threshold as far as the zoom level extent is concerned I'm using my mouse wheel now to zoom on this image and much like was the case when I zoomed in money to mark we get to a point where the value of this data is diminished I'm not able to discern individual features obviously I've only got a small tile here but even if it was a larger area the width of that road the width of the access road into the new building I can no longer see that if we were working with vector data the vector dimensions would be retained regardless of our zoom level suya you can still see a road or you can still see a point regardless of what zoom level you're looking at but with raster's there is a more finite useful range for that data and if you encounter this issue and you want to limit the zoom level expand it is an option in global map or simply by right-clicking you can choose to set the zoom levels within which each layer will be displayed and I'm gonna do it right now but this is the interact this is the dialog box where you can specify the dimensions either based on a size of the file or probably more appropriately within a certain scale range and this scale you will note at the bottom of my screen here right now at my current view I'm at about a scale of 1 to 13,000 almost 1 to 14,000 and it doesn't have to be precise but I could define that as my threshold of that was appropriate by simply putting 1 to 14,000 as my upper level view and perhaps 1 to will zoom in a little closer here and find out how far we will be able to travel with this imagery again but until it gets pixelated we're looking about a 1 to 100 perhaps we could round it to so again you can limit the zoom level a view zoom level extent of your current display of your raster data that means you're not going to waste time panning and zooming and redrawing raster data when you're not actually gonna use it and you can apply that to a single file or to multiple files concurrently another thing we can look at while we're exploring this sample imagery is the metadata if you click the metadata tab or the selected layer and the overlay control center as with any data layer in global mapper it gives you a summary of what's embedded in this layer and you're scrolling towards the bottom you can see as I sort of guessed the pixel width and the pixel height you can see the resolution of the data is included here and we also have information on the projection that was applied specifically we have the epsg code for this projection this projection is UTM zone 19 and that is a coded right here you can actually apply the projection parameters by entering this code the confirmation of values at UTM zone 1993 meters is the projection parameters you will also see information about the bounding coordinates for this layer you will see the covered area as well based on your units of measure you'll see how much area is covered by this so essentially a summary of the contents of this data is available right here in the metadata and the metadata tab we also can get more details on the projection parameters as noted here because it's UTM zone 19 it's given us the central Meridian as well as the false easting Valley which are standardized in UTM if I choose the feature info button in the toolbar now we have used this extensively when we work with vector data to extract the attribution for a selected feature whether it be a point line or area for working with lidar FA if it's part of a point cloud you can get a ace a breakdown of all of the attributes recently we introduced the applicability of this tool when working with raster data so you can click on any point in your raster map data and you can get a breakdown of what it sees at the pixel level RGB and the Alpha band are included me here you can see that information display it you can see display that as a bar graph and you can see the relative weight of each of those color values within this specific pixel it also views a line graph a few months just different ways of visualizing that data you can see the specific location of that pixel row and column dimensions in pixels so 734 pixels on the 730 fourth row of pixel and the 1080 sixth column of pixels defines exactly where that one is so that's a new application for the feature info tool whereas change to working with raster data now let's take a look at some other examples of raster data some of you may have worked with yourself or it kind of expanding the extent of raster data beyond just simple aerial imagery such as we're looking at right now so this is another common example of raster data this is a USGS map those of you who are in the United States may recognize this is the standard one to 24,000 series often referred to as this seven and a half minute series Maps and this happens to be coverage for the Maine State Capitol just up the road from where I am right now this is a raster dated raster file and it shares the characteristics of what we were looking at previously zoom in far enough and you start to see individual pixels in this case there isn't the array of colors that we encountered when we looked at our aerial imagery in fact this is a fairly limited array of colors again the zooming out they merge together so you can start to discern individual features but there are limited colors that this on display we're gonna address this in a workflow context a little bit later this is an example of a raster layer that was derived from a scanned map and a paper map originally was the source that was scanned and rectified or registered to apply Geographic intelligence we're all gonna do that together as part of this presentation we're going to go through that workflow how do we do that how do we transition from just an image whether it be a scanned image or just a raw photograph and apply to Africa geographic intelligence we'll do that in our in our presentation but that's how this data was derived just another example of a raster map a raster base layer in this case a variation on that theme is the map you see in front of you again or another example of a raster layer this is a a navigational chart any of you who are pilots will probably understand this a lot more than I can obviously the symbology that's applied here is most applicable for folks who work in in aviation but it is an example of another raster layer and you can see again zooming and zooming out we started to see the individual pixels that define they the resolution of this image this is an example of a satellite image and specifically this is an example of some data that was downloaded from the USGS earth Explorer or earth Explorer site this is Landsat data specifically this file is the red band now it appears as a grayscale image in global mapper but essentially this defines within that collected Landsat satellite imagery only the red band now we are going to use this one a little bit later as well we're going to apply this data in a raster calculation process because we want to isolate individual bands in order to perform that calculation so a satellite image in this case again another raster image derived from Landsat now chances are you're not getting the full effect of this example without the benefit of having some 3d glasses the sort of glasses you may put on if you go to a 3d movie this is an anaglyph image obviously the individual bands have been offset slightly this is a the way it is able to play a trick on your eye with those tinted glasses the red and blue glasses I guess I'm actually wearing some right now and you'll have to take my word for this but this image actually appears 3-dimensional as I move my head from side to side this building appears to to move with me I can actually get a three-dimensional context it's still a standard image it's still a flat image for all intents and purposes but because of the way it's been processed it gives the impression of 3d this is actually a city in Holland and one of the folks I met with in at a conference recently this is the business that they're involved with is a creation processing of these 3d images that can be served up through web map services so just another example of a raster image now this final example is fairly familiar to those of you again within the US this is a the area of Boston very famous Boston Common here I'm also the Boston Public Garden right in the center of the old part of the city of Boston this is a raster map but it looks very much like a vector map and the reason for that is because this was actually created as a vector map and rasterized this is OpenStreetMap data another streaming service that's available through global mappers map services online data services and it essentially provides a picture view of data that was originally processed and raster for in vector form you can access the vector files as well but this is a rasterized version of a originally a vector file and proof of that again is if i zoom in if this was traditional vector data it would scale based on my zoom level but as you can see i'm starting to see the individual pixels in this layer now so that's just some examples of raster data it's not just imagery but there's a lot of different variations on the theme of raster data now one of the things that we are often asked is about reprojection and I think I will address this in the context of raster data obviously whatever the particular data files you have loaded same procedure works if your workflow involves accessing data accessing imagery accessing raster data for the purpose of reproduction into a a different system global mappers reprojection function is initiated from the configuration dialog box I'm highlighting that button right here in my toolbar and if I click on that button um and I go to the projection tab confirmation here of the current active projection this is the made of projection that was associated with a file that I imported if I need to reproject I simply choose the reprojection parameters the new coordinate reference system information I want to choose the state plane system in this case and I will choose not Oklahoma North that's not gonna work for us but I'll choose them Massachusetts East the mainland zone actually in Massachusetts and we'll leave the other parameters just as they are for the time being we'll click OK and what I've done there is essentially reprojected a confirmation of that' you'll see along the bottom of the screen so if your raster processing workflow requires you to take a file and we project it I've gone through part of that process the next phase would simply be an export process because the on screen projection parameters will be inherited by the file that you export that's how reprojection works so in the next section we're going to talk about some of the can image processing components of global mapper we're gonna look at adjusting some of the characteristics of the raster data transparency for instance what about contrast and introduce some other image properties ability to change the visual characteristics of your raster data now any of the changes that we apply are are done at the layer level so I have a simple little tile of some imagery here and I'm gonna click the options button in the overlay control center and because this is a raster layer this array of tabs this array of parameters is going to be distinct from what you'll see are different what you'll see when dealing with vector data work when you're dealing with vectors you're talking about the style of the line you're talking about the label that's applied to the point things like that in when working with raster data obviously we're talking about a features that are represented by an array of pixels so the options are gonna be different and you'll notice some of these options here you can notice a simple color intensity adjustment slider I'm gonna apply some of these settings to this sample you can see on screen and we can see the results color intensity if I obviously I make the the colors darker we'll just apply that we don't have to change the dialog box as you'll see it obviously makes that color a lot more intense and there's a section on array a Tabish it's a for contrast adjustment and you can define more precisely the color balance by sliding the red green blue values back and forward and assist a percentage value for each um and often if you need to fine-tune based on perhaps the initial quality of an image it's a good idea just to do some trial and error if I want to increase the relative blue in my image I'll just simply apply that and you'll see it gives it a kind of a a cooler cooler look when I increase that blue blue value so again trial and error as far as these adjustments are concerned we have contrast adjustments that wear as well now the way that you define contrast is based on a percentage stretch I'm gonna change this standard deviation value to 1 and with this occur apply that and what you'll see as a result of this is a big the distinction between the color elements and the color pixels become much more pronounced in in many ways it's easier to distinguish at this level than it was when the there was no contrast adjustment applied I look specifically at the trees within the little turning circle around about here if I revert back to the original you'll see it does look a little washed out so I'm applying that linear contrast adjustment certainly helped some of the other options you can change the transparency now for this I'm going to bring in another data set another layer and global mapper we're going to look at essentially two different layers concurrently now we're dealing with two rasters here so both are opaque native natively and we can use our image slider our Sarma image swipe I'm sorry right from my toolbar as you can see where my cursor is to pull back one of these layers to see what's underneath and as you'll see I have some underlying imagery and I have a small section of the topographic map that we were using earlier sitting right on top now if I go back into the options looking at some of the transparency options I can adjust the overall translucency of whatever the layers I've just realized I've selected the wrong layer I'm in cancel I'm going to choose this this topmost layer the USGS layer and again we will adjust the relative translucency I'll bring that down to about halfway we'll click apply to see what the end result of this is and it'll make the uppermost layer semi-transparent so we can see the delineated roads we can see the contours but we can also visualize some of the actual visible features from the aerial image now this is not an ideal solution because in a sense what we're doing here is we're compromising both layers we're washing both out but if there is a need for you to visualize two raster layers concurrently then certainly that is an option let me go back to the opaque again and I'll apply that because in many situations a preferable solution might be to select a specific color to be transparent and as I mentioned previously this layer there is a limited palette layer in other words there are very few colors actually displayed we can see greens we can see reds we can see blacks etc and what I want to do this scenario is to specify a particular color to be completely transparent and I can depending on the type of data I'm using I can apply a fuzziness value which essentially will allow me to determine whether a precise color or variations of that color would be acceptable because this is a limited palette image we're not going to worry about that we're gonna choose the green color in this case and I want to simply select that as my transparent color we'll click OK and we'll apply that now what you'll see as a result of this workflow is that areas that are green are now transparent in the image and I think is for the best seen up close the window first if i zoom in just a little closer you'll see we can still see the contour lines that were from the original scanned map we can see the line work that was in this case a track but we can now see the underlying imagery where there are now holes where the green used to be so a specific application of transparency applied in this case a slight variation on that theme is to apply what's called a blend now I'm going to bring up a new instance of global mapper and with essentially the same top level data but this time if I pull back and reveal what's underneath this time I actually have a terrain layer and I have used to daylight shader as you can see to visualize this terrain layer essentially what I've done is remove the default colors that are typically apply to terrain layer and this is essentially just the hill shader pattern this this process will work with any raster data or any combination of two raster layers in this case it works well even though the underlying layer is actually an elevation layer technically it's still a raster layer because what I'm gonna do now is run a process to blend the two images together where we attempted to adjust the transparency to work with two layers concurrently it was limited in its success we weren't able to keep the Christmas of the image we washed out both images essentially but if we apply a blend it'll allow us to essentially accentuate one image or accentuate one layer with what's underneath now in this case again I'm playing with elevation data and a topographic map I'm gonna blend the two together that process again is right here in the options dialog box this time blend mode now there's a very long list of blend options in here those of you who are familiar with working with graphic files may be useful to shop or some of those graphic applications will probably be familiar with a lot of these some of them are fairly complicated in terms of how they're applied the simplest one to define is the multiply one because when you multiply the values in a pixel with the values in the pixel that's underneath you essentially get an accumulation of the values in those two pixels and so it accentuates based on what's underneath the pixel that sits on top the best way to show this or to describe this is actually to show it someone click OK after applying a multiply blend and as you can see the darker areas from my hillshade pattern are now embedded in the image above it's still two different layers I can still turn off the imagery layer that texture will disappear but we've asked global mapper to blend the two together essentially building a that multiplied value at every pixel if I intended this as a final product and I exported this file it would inherit the characteristics that I've applied to in other words it's a what you see is what you get if I need to capture this in an exported file format so blending is in many ways a much more effective way to work with two raster layers concurrently next example I'm going to show involves working with I can't two raster layers but in this case we have a problem because on the left side of my screen we have an image that's a fairly low resolution image relatively low resolution image and it seems like it was perhaps taken with maybe different technology different different light processing so there's a distinct seam between the two and if I wanted to create an integrated or a combined and coverage map using this imagery well there's no magic wave of adjusting we probably could talk a little bit about some of the contrast adjustments to maybe make them similar but I'm still gonna see this very very well to find line what I wanna show you now is a tool that lets you feather abutting images or overlapping images as is the case in this in this example again back in the over a control center I want to choose the high resolution image which is the little tile subset essentially which is sitting on top of some low resolution data which you can see on the left side of my screen and if I go to the options there is a tab that will allow me to adjust the feathering if I select that tab it isn't unfeathered by default but if I click the feathering tab I can choose based on this image style which of the edges to feather I want to choose all for them I can also specify the border width in other words how much along the edge of this high-resolution image is going to be blended different use of the term blended or feathered into the underlying image and I'll start with a hundred pixels trial-and-error as we said before is sometimes the best approach we'll simply click apply and you will see then that hard seam is no longer there's no longer visible it's quite easier to see that images are still different but we don't have an abrupt transition from one image to the other we can extend this along extended up to 200 pixels and apply that and we'll see it again it extends that feathering so it transitions in a much more gradual way between one image and the other and so we're back to where we started this section another option that you'll find in the raster options dialog box is color great now this is a little bit more of a complicated more involved image processing tool what you see here is a breakdown of the RGB the theif we go our color bands red green and blue um within each of these bands you'll see we have an input range slider and an output range slider this allows global mapper to determine what it reads within the file and how it renders those values so if I adjust the efference to the input range I'm gonna limit it for my blue color let's just apply that what you'll see on the screen is it really changes the the characteristics so you can be very specific on how it reads that channel on how it interprets that channel and ultimately how it displays that channel this tab also gives you the option to provide a saturation value for the collective colors and this is gonna be on a range of 0 to 1 and if I put a 0 in there what you'll see is my image essentially becomes a grayscale image so if your intention is to create a grayscale of an image this is where you will go to do that under color grade you can bypass the manual settings and just set the saturation value to 0 and as you'll see it creates a grayscale image so in our next section we're going to take a look at some of the physical modifications that can be applied to imagery specifically we're going to talk about cropping we're going to introduce the idea of tiling imagery that we'll be taking a large tile a large file I should say and breaking it into more manageable sizes then that can be initiated during the export process as you will see and as I said at the start will also introduce mosaicing now there's not really a great deal to talk about as far as mosaicing is concerned because it happens automatically if your workflow requires you to take multiple files merge them together into a single file seamless file just simply export and by default global mapper will export all of the loaded data in a single file so cropping tiling a mosaicing so I've loaded up an imagery tile and also going to load up a a second layer this is I'm going to drag and drop from off-screen here this is a shape file and the shape file if I turn off the imagery you will see it contains basically a boundary file this says happens to be a town boundary innocent area it's a vector area file I could also have drawn an area that would also worked if it's appropriate for your workflow but this is obviously a file that I had already pre existed so I'm gonna use that tile to limit or constrain the extent of the underlying image I'm gonna initiate a cropping process where this work is very simple we simply select that tile by the way you'll notice what I'm selecting a vector feature out of habit I draw a box around one of the borders that that's a useful workflow in global mapper simply because if there are multiple features that are likely to be selected it will focus specifically on the border that you've chosen so in my case doesn't make any difference I've only got one feature but if you have multiple features perhaps overlapping you can specify which one to set it to select now I've got my border selected I'm gonna initiate initiate the krumping process once again this is back in the options and this is one of the tabs that we did not look at previously choosing cropping gives me various alternatives I'm gonna come back and revisit one of the ones at the top in just a few minutes I could crop the image manually if I happen to know the specific boundary lat/long values for the area if I'm interested in so if you have that noted you can simply key those in you can crop by a certain number of pixels around the edge of a layer in other words if you want to tidy up maybe a border that that wasn't processed correctly you want to just simply remove that to tidy up your image just a little bit you can specify the number of pixels in either side I'm gonna skip all the way to the bottom I can crop to a currently selected polygon which is exactly what I want to do and I'm going to keep the dialog box open for just a second if I click apply it will as you will see limit the visibility of that underlying image to what I had defined in the boundary file now it is worth noting that the image the sections of this image that are gone are not deleted we haven't physically removed them if I want to revert it back to its original form I simply go back up to no cropping and click apply again and you'll see it's back to the way it was so cropping to a defined area very simple process just initiate the cropping right here in the raster options dialog box you can also perform the same cropping during export so if your intention is to export a file to capture a file and part of that workflow requires you to limit the extent of what's exported you don't have to do it here you can actually do that during the export process there is a a export bounds tab that you'll see for every format that you export and one of the options is to export just what's within the bounds of a selected polygon as you as we've done right here it's also it is a good idea to actually visualize the results just in case so um it may be a better workflow to actually initiate the cropping prior to exporting so we can see the results now we had this question come in just a few weeks ago um what if I want to crop imagery but leave the middle are essentially crop everything but that's what's in the middle notice I want to leave the image around the outside and remove what's inside the town boundary well I don't think in this particular example it probably makes a great deal of sense but we'll go through that workflow nonetheless in other words I want to cut a hole in some imagery si us instead of removing what's outside the workflow for doing that involves one additional step and I'm going to close this dialog box I'm gonna select the imagery tile that I have on my screen and I want to right click that tile on that tile I don't want to choose B boxes this is a tool in global mapper that lets you create a bounding box around any layer vector raster or elevation layer lidar if you work with lidar data you can create a coverage area essentially and you can do on one of two ways either as an MBR which is essentially a rectangular area or you can simply create a polygon that more precisely outlines the extent of the features that are in that layer most applicable for raster data or for lidar if you use the no option here I'm gonna click yes in this case it'll create a rectangular box difficult to see it right now so I often turn off a couple of additional layers there we go we've now created a bounding box around that image I want to turn on the boundary the internal boundary as well because what I'm gonna do now is wanna cut a hole in that larger polygon the way I do that is using the digitizer I select the internal now this is a case where drawing that bone that box around the the border is a good idea because now I've just selected the boundary I right-click or back in working with vectors now very briefly I go to a crop combined split function and I'm going to cut the area from another area I'm gonna cut a hole in the boundary and will go ahead and choose the outer boundary as are inherent in this case as you can see the name of the the cursor and what I like to remove what's in the middle I want to say yes and now I have a polygon which essentially is the utter extent but not include the middle that's my whole my whole there holding the polygon now if I turn my imagery on again zoom in just a little bit so we can see the full effectiveness if I want to crop my imagery based on a selected polygon and I choose the remaining polygon simply right click are sorry I'm go back in the overlay control center options cropping and now again we crop to the currently selected polygon because the polygon is now has now got a hole it leaves what's outside removing what's in the middle and we can turn off the vector features that have already performed their their tasks and now I have imagery in which this center section has been removed so that's the inverse of the standard cropping process we'll show a variation on the theme of cropping now for this we're going to go back and visit one of the layers that we looked at previously um let me actually load it up and I go I'm gonna unload this file and I'm gonna load up one of the USGS maps that we looked at previously I'm just going to drag and drop it onto my screen here and we'll just choose this example now this is again standard USGS map we looked at this for a couple of enero is blending and adjusting transparency one of the things you will notice here is that there's a lot of information around the edge this is a literally a scanned paper map so it didn't stop at the neat line of the map everything that fell outside was also part of the file that I imported although the information below obviously doesn't have any Geographic relevance there's no features here it is still part of the original map now to accentuate the problem that we're having to deal with here I'm also gonna bring in another tile specifically the one that sits on top and these two files upon each other but you'll see already problem here because there is an overlapping section that covers what's below as you can see so I in order to create a seamless coverage area what I would essentially have to do is to crop out everything outside of the neat line global mapper has initiated an automatic tool for addressing that of a specific issue and I'm actually want to perform this concurrently on both of these maps now if everything goes according to plan everything that's along this neat line are basically for the uppermost layer everything is below the neat line will be removed and for the layer that's underneath the one that's to the south everything that's above the the top neat line will also be removed so with my options button selected and my cropping tab selected I have the option to automatically crop the collar and when we select that and click apply you'll see it has automatically removed everything outside the neat line and given me a seamless transition from one of those quads sheets or one of these topographic maps to the other you will notice the format's that that applies to DRG the digital raster graphics files the BSP files if you're working with geo PDFs etcetera so this is an automated tool that will work with some formats of scanned registered raster topographic maps so I've loaded up a series of four imagery tiles and this is by way of an example of working with multiple data sets and we can see as I turn an individual tile off we can see where that one resides to address the idea of mosaicing it is as I said before an automated process not really something we need to do under great depth about but worth acknowledging nonetheless if I need to take all four of these image tiles and mosaic them together to bring them together from the file menu I simply go to export and I choose image format choose my selected format what I need to export the data in I could choose JPEG 2000 and click OK now I'm not gonna go any further with this process because the process of simply saving the file of this stage will create a single file for all the loaded data whether it's for tiles of imagery or 400 tiles of imagery they will merge together into a single output file and if you do need to export an individual tile well there's a couple of ways of doing that you can either remove or turnoff the ones that you do not need or you can right-click and specifically export that one's selected tile so that is the exception the default is to export all of the data so mosaicing and global mapper is an automated process tiling was the last section of this last topic of this section and tiling is also something that can be initiated during the export process we'll choose the same format JPEG 2000 the tiling process will work regardless of what data or what format you want to export with you'll always find a tiling tab in the export options dialog boxes tiling allows you to specify the number of rows number of number of columns or you can specify the column width and column height you can't do both with them for it well I guess in many cases you can but in this case because we're exporting our entire data set I only have one of those two choices that I can apply I can also specify the pixel size if that's appropriate for what I'm hoping to achieve whichever method you choose you define the distance of that that width and height as it says here naming will be applied based on the parameters below the default is the a1 a2 b1 b2 etc etc and you can define an overlap if it's appropriate how many pixels or percent do you want to overlap with the adjacent tiles if you do need a certain amount of overlap in your tile coverage you can specify that right here so that tiling process again if you recall what I'm looking at on the screen now is actually for different individual tiles of imagery what I'm doing during the export process now is essentially retiling them by defining again whatever parameters I want and it's gonna tile collectively tile all four of the original tiles into a new set of tiles based on these parameters I'm not gonna go any further forward workflow is simply a click a case of clicking ok give the default name it's just like you would name a single file it will then append the the letter the numeric alphanumeric letter sequence that you apply down here at the bottom of the dialog box so that's the tiling process essentially the opposite of mosaicing now I'm going to show you one more method for tiling that gives you a little more precision over the tiling there the mechanism of tiling and that's through the use of the gridding tool in global mapper you can generate a grid simply by defining an anchor point either manually by clicking on the map or you can define the anchor point by specifying the x and y or lat/long values after clicking this button but thereafter after doing that you have the option then to create an array of tiles if you're looking at a specific area you can actually constrain the tiles within a rectangle you see I can fill a selected rectangle or don't have a rectangle right now so that's not available to me and fellows I don't have a vector polygon on my screen so I'm just gonna manually define the extent of my towels I can define a number of rows number of columns and the width and height of each now glancing down at my scale bar I'm looking about a 50 meter I'm just obviously doing this arbitrarily I'm just gonna create a 50 meter by 50 meter array of 10 by 10 tiles originating at this anchor point we'll click OK on that and you will see when my map refreshes I shall now have a series of tiles manually assigned tiles I can move these these are just vector tiles I can tweak them I can rotate them if necessary I've got all the vector editing capabilities that I would have had with would have with any vector files but what I'm ready to export and if assuming that this Norfolk forms the basis of a tiling process when I go through that export process now I'm again will just choose the defaults here go to tiling you will have the option to use this selected area feature or features in this case for my tiles so if I ran through this process I would end up with a hundred small imagery tiles based on this manually created grid that I used the gridding to to create so it's a variation on the theme of tiling so up to this point we've been working with them processing and applying settings to pre-existing raster data layers files that we may be imported or data that we streamed from with a web map services what we're going to do now let's take a kind of a step back and address one of the challenges when working with raster data is essentially getting data into the application that's known geographically intelligent this may be aerial photographs that were not geo-referenced or it may be maps that you have scanned perhaps some old maps that your company has had sitting in that back room that somebody finally scanned they're now in a digital form but you'll want to integrate those into your your spatial databases and the process for doing that is essentially rectification the idea of applying intelligence geographic intelligence to an image file so I've just brought up a view of the file that we want to work with here you may recognize this as Central Park New York I believe this is an early 1900s map I'm not sure exactly what the year of this map is but it's obviously an asterick map it's just a paper map essentially that was digitized that was scanned it has no geographic intelligence what we want to do is overlay this or essentially apply the necessary geographic information to this map that will turn it into aged jus spatial raster layer so this is the raw material I'm going to close this I want to take a look at what we have to work with in global mapper now instantly you'll notice that the alignment of the same geographic area is different that picture that we looked at was aligned well easier from say East and West it's actually just right and left as far as the image is concerned but Central Park this is the area of Manhattan does not run east and west it's running kind of in a northeast Southwest direction so what's part of this rectification process we're going to apply that angle deviation of you like as well as scaling the image so it fits nicely in place this data is the OpenStreetMap data that I downloaded this is a raster tile of the same data that I previewed towards the start of our session we're going to use this as the foundation for the rectification process in other words we're going to identify specific locations in this base map and tie them in to the image that we're importing to apply the rectification process now before we begin this an alternative method for me performing this type of procedure would be to physically go into the field and collect those x and y values at a known location again a location I may be able to recognize in the image that I'm trying to rectify by applying the manual coordinates you can be more specific obviously if you go to a particular location a control point in the field using some high-end GPS data collection tools you can be very specific on on the allocation of that ground control point what we're doing here is going to be essentially identifying those points on a pre-existing layer and we're making an assumption that whoever created this data did so with a reasonable amount of accuracy that may not be the case but in the purpose for the purpose of what we're doing today I think this will be sufficient so when we work with non geospatial data there's a couple of ways that we can get it into the application there is from the file menu a dedicated rectify do Rafer geo reference imagery option which allows you to point to any of the supported raster formats alternatively you can simply just go to the open data file button or option rather and browse to the necessary file now I want to go to my desktop I'm gonna locate that file this is one of our training files so I'm just gonna browse into the folders that we use and this is the file that I had previewed just a few minutes ago this is our Central Park file the adjacent file is the one that we're using for reference so we're gonna bring in this simple jpg file now when we browse to that file global mapper recognizes that there's no geographic information so it asked me what I want to do first option is to manually rectify which we are going to do second option is to fake the coordinates now what that will do is essentially place that image zero degrees latitude latitude zero degrees longitude allowing me at least two to begin the process of working with that file I may then recognize all this is in New York so I can initiate a rectification process after he initially visualizing the image the third option is to load as a picture point essentially this will create a hyperlink to the file at a point that I designate on the map so it is similar to importing a a photograph that you may take with your GPS enabled smartphone it creates a link to where that photograph was taken I get our option in this case is right here at the top manually rectify image and it will immediately load up the rectify image rectify our dialog box on the left side is a sky view of the original superimposed on which is this grid the function of that you'll see in just a few minutes in the middle is a zoomable view of the same image this is what we're actually going to work with to identify our control points and over here on the right side is the view of my current map and when I left the map view this is the area that I was looking at this allows us to browse around and look for areas I look for locations that are recognizable in both we're gonna tie the two together towards the bottom of this window you'll see areas for entering the ground control points these are the pixel locations for places that I identify an image the corresponding Eastern or X values are longitude our Y values northern or latitude can be entered here you can enter these manually you can manually define these values we're gonna do this on an automated way as you will see and then we have a tabular view that will convey for us all of the control points that were used and we'll see those listed here as we go through this process each of these views is you can interact you can zoom I'm just gonna zoom into the corner here and you'll see I can now get a close-up view of I think it's not called Columbus Circle right here in the southwest corner of Central Park and you'll notice now on my adjacent view that grid is now constrained to the area that I'm currently looking at this is a way to navigate around very efficiently I can simply click to go to another location in the image so that's the function of the window on the left hand side zoom in just a little closer so we get a close-up view of the circle as it's called and I'll look at the same location in the existing layer now it is a slightly different configuration but I'm going to make an assumption if I click close to the center of the circle simply click with my left mouse button you'll see a little red dot appears and don't worry about misplacing that dot you can click again it will simply replace it in a new location but again clicking close to the center of that circle that location corresponds with the same Center location over here on the pre rectified already geographically intelligent map having clicked on both of those locations and one in the jpg and one in the pre-existing layer you will notice that the pixel and coordinate values have now been populated based on where I clicked assuming I'm happy with that I can add that to my list of control points give it a name we'll leave it as control point one point one which is perfectly fine and click OK so we have our first point added we could get away with just two there are there is a rectification method that will allow you simply define two points as far apart as possible and that will allow you to adjust the scale and the rotation to hopefully align the the map fairly accurately I'm going to actually choose four different points I'm gonna move my position over here to the opposite corner the the north corner I guess I want to do the same on the registered map I'll pan just a little bit and I'll zoom in a little closer here and I'm seeing again a slightly different road configuration let me choose what I would approximate to be the center of where that circle is and again we'll click at the center right here as well and again add that point to my list I'm not going to do this with any great level of accuracy today just in the interest of time we'll move to the adjacent corner as you might once again and we'll zoom in and again we have a circle here which doesn't exist in the early part of the 20th century so we'll click I got proximately where that center of the circle would be and once again over here and if we were doing this property we probably would choose an adjacent rule dinner you know some alternative will zoom out one more time zoom over to the final corner and scroll down a little bit so we can see a little more clearly and again the real configuration is so completely different now but we'll assume in the center view that that road intersection right here that looks like East 59th Street right here it corresponds with I think i zoomed in a little too far right here this intersection and again I forgot to add the point last time less you'll have to go back and add our our third point here once again my apologies we will add that final point that's always a a step that you need to make sure you do once you've added your point at that point to the list a little out of order but that shouldn't make it different so I've got four control points you can see them now in the larger map view you can see them at each of the individual map views we can simply click OK at this stage and it will apply those control points to the image and hopefully it will give us a rectified aligned version of that layer so we now have our image geographically referenced and we can look at the quality of the rectification process a couple of methods we can employ which is zoomed in to some of the streets here on the I guess that would be the east side of Central Park and using an image swipe tool which we looked at earlier we can now pull back the overlying image to see how well it lines with what's underneath on just a cursory glance confirms it's a reasonably good alignment here you can see the streets lining up reasonably well we can also look at the transparency option that we had looked at before and temporarily adjust the opacity of the Central Park layer I'll just leave this window open I'll click the apply button and again we can see some of the underlying detail from the OpenStreetMap data as well as the historic maps sitting on top so using these two methods we can verify how our registration was and if necessary we can then modify the rectification parameters if we need additional points remove perhaps points that are causing error we have options for changing that and the way that you can do that I'll just go back to the opaque opaque version again is to simply right-click on the layer and choose rectifying now this can be done with any layer obviously this is a layer that was pre rectified but if I need to I can take an existing layer and override the inherent geographic parameters and essentially manually place that if I need to in this case obviously it makes more sense because this is a layer that I had manually rectified so it's likely that I would on occasion need to change those rectification parameters before you embark on that process by the way I should mention it is a good idea to actually physically turn the layer off before you reracked fi it now the reason for that will become clear when I select the rectification option because on the right side of my screen you'll see the reference map is the original OpenStreetMap and if i had left the registered version displayed it would also be displayed over here so would make the rectification process extremely difficult I'd be looking at the same data that I wanted to rectify as a base map for rectification so obviously turning it off gives me the view of the original map and if necessary I can take points and delete them I can modify them double click on a point it brings it up into the ground control point area change it if necessary I had a new point if necessary so I've could complete editing capability over that rectification process and as I mentioned previously I'll cancel e-r e-r ekta fication if my workflow required me then to take that base image generate a geospatial version of that file and ultimately export that I can simply go to the file menu and run that export process to any standard raster format this next workflow is an extremely useful one and I mentioned at the start this is one of the tools in global mapper which is not immediately apparent and there's a little bit of searching that has to be done to find this function but once you've uncovered it you will find a lot of value in what this does we are going to employ a process we're going to transition or gonna take data in a raster format and generate vectors from that we're gonna generate vector features I like to call this process a vectorization process now the source data you see on your screen is some standard aerial imagery this happens to be an area in the Canadian Rockies and you can see quite clearly in the middle of the screen is a body of water a lake a couple of different bodies of water well we'll use the scenario for this workflow that we didn't want to determine the area of those Lakes how much water coverage is in those Lakes and obviously when you're interacting with raster data that's a little bit difficult because in order to determine that we may have to trace the boundary manually and we're not sure how accurate that would be so what we're going to do is extract the lake area or Lake areas as vector features now this component of global mapper is initiated from the overlay control center and it's done so by right clicking on the layer in question I have the JPEG 2000 layer here I right click and I create area features from equal values in selected layer now values in this context refers to colors we can also employ this tool for extracting areas of equal elevation or indeed of equal slope angle slightly different context we have covered these scenarios in previous online presentations and then webinars so if you want to find more information about working with terrain data in this context you can refer to one of those in this context we're specifically going to be looking at matching colors to create vector features so when I select this option it prompts me to define the parameters for the vector layer that I'm going to create I can first give it a name as you can see it inherits the name from the underlying layer I'm just going to remove the suffix this is going to be called layer Lake areas is the name of our vector layer we're not concerned about the specific attribute that we're going to add to the vector features in this layer because they're essentially all going to be the same we're gonna match the colors I did that only the colors that fall within this lake so they will all fall within a certain RGB threshold if you like and we can define the a feature type we'll worry of like that in this context either what I want to do is to specify the specific colors that we are going to extract we're not concerned about extracting all pixels or all colors rather what we want to do is only create areas for the selected colors and the selected colors I have them in my recent list here defined by RGB values which by the way you can see at the bottom of the screen here over on the bottom left corner of my screen you can see the RGB where my cursor is located so if I had moved my cursor over the lake it would have shown me what the RGB czar and I would have transposed those into this dialog box which I have already done and selected this color now if I went with just the selected color and run the extraction process it would give me a handful of pixels maybe I don't know several dozen pixels maybe a few more let's specifically match that color what we want to do is extend that threshold beyond just that color and we put in a value here to achieve that that can be up to 256 if we choose 256 that would basically imply that all of the colors in this in this layer will be extracted a value of zero would be just the specific color so we're gonna move that the scale just a little bit we're gonna put a threshold value of 20 in here and often when you're going through this workflow trial-and-error is the best approach if you put in a value and you're not quite getting the colors you expect you can come back in and expand that threshold just a little bit but the end result of this will be we're going to match colors which were defined by that RGB value and 20 a scale of 20 above and below 20 out of 256 above and below that selected color and a final thing I'm gonna do is to limit the extent of this analysis just in the interest of time I'm gonna draw a box manually around the extent of these bodies of water and i'm gonna ask global map but just to look inside that area i'm not interested in anything beyond the bounds of that box and we'll click OK and when this dialog or this status bar completes you'll notice I have vector features on my map and I have over 7,000 vector features well we're deviating a little bit from raster processing but we might as well finish this workflow even though we're dealing with vectors not obviously there's a polygons in here which I don't need those that are in the forested area match the color threshold at applied so I need to remove those now the easiest way to do that using your digitizer right click go to advanced selection options and you can choose to select areas or islands and holes essentially that are smaller than a specific size or a selected size and just again from the trial and error process having gone through this before I'm gonna leave the two and 930 square meters as my threshold anything larger than that score that size will be retained anything smaller than that size will be deleted or will be selected I should say and ultimately when I hit the delete button will be deleted so we'll click OK asking me if I want to only select the islands and I say no you can see now they're selected what you can't see is me hitting the Delete key on my keyboard and I now have removed all but three of these vector features so I was able very quickly very easily to extract based on a matching color areas that are recognizable in an image and if I did continue the workflow to the next level I would be able to determine the Pacific dimension based on the measurements that are associated with these vector polygons in this next workflow we're going to take some satellite imagery specifically some Landsat imagery that is divided into its individual bands and we're going to take two specific bands the red band and the near-infrared band from our sire our Landsat data and we're going to perform a calculation the overlapping pixels with a pixel sitting on top of other pixels are going to be the basis of this calculation and we're going to perform a numeric calculation to determine a quantifiable value and ultimately to build a gridded surface a gridded model that defines that become the calc between those two pixels specifically in this scenario we're going to calculate the naturalized different difference vegetation index NDVI this is a gauge or a measure of the relative greenness of an of an area and you'll see as we apply this calculation it tells us where vegetation is most green and we could assume where the vegetation is healthiest we're actually going to perform this analysis twice once for a June timeframe and once for September and we're going to determine based on a comparison and a calculation the difference between the greenness within both of those timeframes on the screen you'll see one of the bands essentially one of the Landsat bands and if you look at my overlay control center this one is June and because this layer is on the bottom in the near infrared bands on the bottom this is the near-infrared channel for June I'm gonna use my image swipe tool and pull that back and we'll see then the red band for doing the second to bottom item in my over a control center so the overlapping area there is exactly the same area but the overlapping pixels within each of these two images are going to be the basis of the calculation well repeat the process in just a little bit for the September month as well um from the analysis menu the raster calculation process is an item right here towards the bottom where we apply a formula to any loaded data now the pre-selected options in my overlay control center are carried over so I'll just retain those we'll click OK and gives us the formula creation dialog box where I'm gonna ultimately create a new raster layer a gridded layer that's going to be based on the calculated value for each pixel so the first thing I'm prompted to do is to give the layer a name I'm just going to call this one Jun it is the NDVI will remember that but it is June's layer so when we see an overlay control center we'll know it's the NDVI calculated for Jun there are a number of pre defined formulas that can be chosen from here in the this dialog box you can also by the way add a custom formula if you want to define the custody parameters for your calculation based on imput you certainly have that option but I've got a NDVI pre-formulated wanna select that I'm gonna add that band right down below and you'll notice the NDVI formula is band 4 - band 1 / band 4 + bad one now this is actually derived from Landsat 7 older generation of the Landsat data were banned for was the near-infrared band band 1 was the red band and the as you'll see in just a second the designation of those bands has changed with Landsat 8 so we actually need to manually assign the appropriate layers that we have an overlay control center to represent the the bands as indicated in the formula here this will be a gridded layer so we're going to use a shader to represent the results and the mdvi shader is at is available now in global mapper that was a fairly new addition and it will be selected by default so when this process runs we will actually see the data rendered with that NDVI shader we'll click OK I must with this dialog box having added the formula um this is where we associate the individual layers that we have in our overnight Control Center with the bands as per the calculation well as I said band 1 is in the formula it represents the red band even though it's band 4 with the Landsat 8 data it is technically band 1 as far as the formulas concerned so I just have to make that Association consequently band 4 in the formula is band 5 now which is the near-infrared band so that's really all I have to do in this dialog box run the calculation by clicking ok and it will show me the index of relative greenness the NDVI index and you'll notice on the left side of my screen the NDVI shader indicating shades from blue through green indicating greenness now blue would be with typically water areas that are white would typically be impermeable surfaces like contact get pavement and then obviously increasing values of green are represented as vegetation or vegetation areas on our map now I'm going to quickly repeat the process using the September Maps you want to turn off the gridded surface I just created I'm gonna repeat the NDVI calculation using September's layers exactly the same procedure its pre-selected here because I change the selection over the control center click OK we'll call this one Sept 4 abbreviating September add or NDVI once again and it populates this little dialog box with a confirmation of the calculation once again assigning band are our band for layer 2 the band 1 in the calculation and band 5 to band 4 in the calculation and once again clicking ok runs through the calculation of the overlapping pixels and gives us a September layer now I want to turn off the original Landsat and we'll focus specifically on these two so gridded surfaces I wanna zoom in just a little closer here so we can start to see a little more detail first thing to note if we use our image swipe tool with September's layer I'm sorry let's do either gateless to turn in september on with September's layer visible on top if i pull back you'll notice in certain areas in june there was a heightened level of greenness specifically over here on the left side you'll see there were areas that were significantly greener in june than in september and that would be fairly typical in this area i believe this is in Colorado where post winter early spring or late spring I guess it would be in June there is a lot more moisture a lot more greenness from that pre summer vegetation pattern after the summer in September through the end of the summer you'll notice the the relative greenness in this area has diminished however you will notice there are certain areas in this agricultural area that actually have more greenness they're not cultivated right where my cursor is located in the middle of the screen you'll see one of these concentric irrigated areas which is a lot greener in September than it was in June and the reason for that is obviously it was irrigated over the summer we can actually model that difference by performing an additional calculation and that's done from the analysis menu we could go back and actually formulate this on the raster calculator again but this is actually pre-configured under the combined compare to rain layers option this is a a tool which is more commonly applied when working with elevation data but because we're working with essentially similarly gridded data we can apply a calculation in this context now I want to do that's very quickly I'm going to choose September and I want to subtract June I'm using the subtraction operation you know there's a lot of different operations can be applied here these are pre-configured calculations apply to two gridded layers considering this in the context of elevation data you can see you can define the maximum between the two the minimum or the average between the two overlay overlapping layers in my case I want a a subtraction where I maintain whether it's signed and it's going to create a combined elevation grid I might want to rename that if I took the time to do that NDVI difference might be a good appropriate name we'll just click OK and we will generate a new gridded layer and I want to turn off the other layers it actually has applied my day light shader by default probably not the best choice I want to choose the gradient shader in this case this is probably the best one this shows me you can note on the scale areas which have seen an increase in their relative greenness those are the lighter colors towards the top on those areas which have seen a relative decrease with the middle point being right here right in the middle here you may want to develop your own shader for this purpose where it creates a very distinct cutoff between those below zero and those above zero but quite clearly now I can see significant areas within this cultivated land which are greener in September than they were earlier in the year areas in the more natural habitats in the forested areas are slightly darker than they where in other words that value is slightly below zero so they are less green than they were earlier in the year so that initial analysis was based on a calculation of the multiband Landsat imagery and then the comparative analysis by simply subtracting one from the other to get a visualization of relative greenness over there over two different seasons as you can see my finest final bullet here is best practices it's almost like I want to give some advice working with raster data what would you suggest I do when I work with my raster data I'm gonna introduce a couple of workflow optimization options even within the context of Google of working in your override control center will talk about grouping data we'll introduce the idea of a map catalog for working with raster data specifically large volumes of raster data will introduce the batch processing tool a lot of people who have been using global mapper for a while have now have never encountered this ever since I was talking to somebody recently who wasn't aware of the fact that batch processing was an available option I'll also talk in theory about scripting I'm not actually want to take the time to develop any scripts but introduce the idea of being able to automate workflows through the creation of a script and as I mentioned at the start of our session if you're interested in scripting there is a a recorded presentation that we did we've actually don't let several times which introduces the scripting process and you can refer to that to expand on the on the scripting process illustrate some of these workflow optimization options I brought in the same for imagery tiles that we looked at previously this is just as a hypothesis a hypothetical example for working with multiple data tiles multiple imagery tiles needless to say the procedures I show you here could equally we'll and perhaps more appropriately be applied when you're dealing with significantly larger volumes of data if for the purpose of illustration I'm just using four tiles in this case as you can see all four tiles are visible all four tiles are turned on and I have four line items in my overlay control center each of which allow me to turn the tile on to individually apply certain parameters or settings go to the options etc etc so they are for all intents and purposes stand alone individual layers in global mapper I want to show you first is a very simple tool for simplifying and cleaning up your overlay control center and that's through a process called grouping with all of the selected layers selected all of the loaded layer selected I should say I right-click and I choose group now grouping is a very simple procedure where I simply type a name I want to type the word Agusta that's the coverage area here and simply click okay you will notice in the overlay control center what was previously four items is now one item called Augusta and you will also notice that there's a little plus sign right next to it and if I click the plus sign I have the individual tiles still visible here which if necessary I can collapse and if necessary I can apply options or settings to the group by simply initiating the same procedure I would have done for each individual layer so collectively now it can change transparency feathering any of the other options that I had previously looked at I also if necessary have individual control over specific tiles so I still have you know layer level control but I can simplify and improve my workflow by collapsing the group into one line item so obviously if you've got hundreds and hundreds of imagery tiles you do not want to have to be scrolling through the overlay control center in order to perform any processes or to find additional data that may be in there somewhere collapsing these into groups is a very very efficient process as far as managing multiple files is concerned now groups can obviously be a hype light beyond this context you can apply grouping to a group of layers may be of different data types that pertain to a particular project or job site and they do not have to have anything in common in other words as far as the structure of the files or the file format is concerned but it is very common to apply grouping in this type of situation removing a file from a group is equally simple I'm gonna take this last tile but right click and your lowest group is still available here selecting that confirms the name for me simply deleting that name and clicking ok will relegate that individual tile to be a standard item in the overlay control center outside of the group so removing the name essentially controls the group and for that matter if we choose all of the remaining tiles and again simply remove the name it removes a group completely so grouping very simple tool for managing data the next level up as far as data management is concerned is to create what's called a global mapper catalog and I can do that either as a external process where I build a catalog loading data or as you can see I've got some data loaded so I'm gonna initiate that process from these four tiles that I have in my map with them all selected or a right-click I'm gonna choose create map catalog from selected layers a map catalog is a data management function of global mapper that allows you to create a single file you'll load a single file into global mapper that ultimately I are consequently will point to many source files so in this case again there's only four tiles to begin with but it could equally well apply to hundreds and hundreds of files I'd create the catalog it first prompts me to give it a name I don't give it a name called test and will drop it right on my desktop and will click OK or save in this case it has saved it catalog it has automatically added the tiles that are currently my workspace to this catalog and you can see the path defined here from you know where my data currently resides and a couple of things here I can add additional data either individually or based on what's within a defined directory I can remove individual tiles as necessary so I've got a a management tool that lets me determine what's part of this specific catalog I also have the option to go into the modify options like we did before with individual layers to change again things like the band setup projection cropping etc etc once I'm done I click OK and I want to unload this data individual tiles control.you is the keyboard shortcut by the way and I'm gonna load up that catalog it should be somewhere on my desktop and it's right here called tests now as a consequence the same maps are being displayed the same four tiles are being displayed you may notice they came in a lot faster and a single line item is now displayed am i over the control center this line item is something that global mapper manages as an individual entity as opposed to managing for 10 100 different individual tiles so global mappers processing is much much more efficient because it sees a single file as opposed to multiple files if I need to change any of the parameters on my catalog I can go to options and I go back into this dialog box I think I can change any of these settings as needed if I need to remove and I don't from the catalog I simply remove it change the raster's characteristics or the vector characteristics if that's applicable you can do that right here with this button so map catalogs managing data collectively all of the imagery tiles that you have for a certain area can be defined as one individual file as far as global mapper is concerned and it certainly improves efficiency as well as usability within the application you're simply loading one file removing one file as needed now the final thing we're going to show is a tool for batch processing I will leave the current data on the screen right now because in truth it really doesn't matter the batch processing tool is actually an external function of global mapper you're not actually dealing with data that's loaded on the screen this is initiated from the file menu and you'll see about half way and just more than halfway down the batch convert and also reprojection by the way is another option in here allows you to take and whatever files in whatever format and define the conversion parameters and then immediately export those without actually having to load them into the application itself so what I want to do in this case I want to take the JPEG 2000 files that we've been playing with these four tiles the original four townsman Saguna scroll through and find JPEG 2000 and let's export them or transform them or convert them I should say into ECW files and we'll click OK now once I've defined the input format an output format I now have the option to add all of the data and I can do that either on an individual level or on a directory level either way it will work in my case I'm going to go to my webcast data folder and here are the four tiles that we've been playing with we'll just go ahead and add them to this list and again they do not have to be loaded in the global mapper this is independent of any loaded data the output directory the destination I can specify the file name I can specify either it can be exactly the same as the file name or I can append or append a text string I can define the projection parameters by default is using the same projection that was used for import but I can change that in fact if all that I want to do is reproject but maintain the same format I can choose the JPEG 2000 in an JPEG 2000 out during those first two initial dialog boxes and just simply change the projection parameters and it will run through that process there are options that are specific to individual formats as far as how the procedure works but once you have all these settings applied it's simply a place of plea a case of clicking ok and it will run through that export that transformation conversion process for you and I've only got four tiles here so it should not take too long to run through you can see the status bars they're running through and essentially batch processing my data now while this is chugging along let me also talk briefly about scripting again with apologies not something we're gonna go to any depth with this particular presentation but if there is other other resources that are available to you and there's also an online reference global map your scripting allows you to automate workflow by essentially defining the a series of commands and based on those commands a series of parameters or settings in a simple text format so I like to tell people if you can type if you can type words in a notepad file you're well qualified to creating a global mapper text in fact the structure of a workspace which is the fundamental file management component of global mapper is identical to a global mapper script so you can actually base your scripting procedures on workspaces that you actually save within the application so again not going to go any further with that today but scripting is an option to automate a lot of work floats standard raster data processing conversion reprojection cropping tiling all of those procedures can be automated in our scripting process it looks like I'm just about to the last of my converted tile is going from JPEG 2000s to to the ECW files and I'll just off-screen here I'm not even sure what directory I was writing up to so we'll assume it looks like it's been written into a a temp folder here so let's go ahead and notice our time is just divided up let's go ahead and wrap this up I'll go back and bring up the contact information I refer to earlier as with all of our webinars all of our presentations and we have continued help if you have questions on any of the topics that you see in this recorded version or or any of the previous recorded sessions and the geo help a blue marble geo comm email is where you can go out put that link in our YouTube description so you can go there directly if you're looking at this on our web site and you can go to our support menu at the top of the screen and you'll find your way to our help area and there's a submission form there you can access the folks in our help menu or our help site our department it will essentially send an email to the same Inbox the Google map or forum I referenced earlier as well if you're not currently using the forum view not a forum participant I strongly encourage you to get involved great active community of users post your questions answer other people's questions if you feel so qualified Google map or forum calm and of course there's our email address if you're not currently using global mapper and you're maybe interested in some of the tools that we cover today as well as perhaps other the content of other webinars and webcasts that we've done in the past but you can download a copy go to the global mapper menu and you'll be offered the option to download the application you can request a two-week free trial and put it through its paces so and that is that for today I thank you for taking the time to watch the presentation and we look forward to speaking to you next time thank you

Channel: Blue Marble Geographics

Views: 22,240

Keywords: Global Mapper, Global, Mapper, GIS, Raster

Id: ZS4LHR8dO7E

Length: 94min 55sec (5695 seconds)

Published: Thu Nov 19 2015