Drone Aerial Mapping on the Cheap

all right so this is a technique for making high-resolution aerial photographs from drone images using software that we already have so let's see how this works the first software we're going to use here is called image composite editor and this is made by Microsoft and it's freeware and so install it launch it and then you want to go new panorama from images and you see here I've got a whole bunch of images that were taken from my drone so I flew a path using drone deploy and capture these images and so it's going to load those in now the downside of this technique is that you have to georeference the image yourself but we can do that in ArcGIS and I'll show you that so here you can see all those images are loaded in and so then the next step here is stitch so I'm going to hit next and it's going to go ahead and align those images and stitch them together into one big image so that takes a little bit of time so drink a cup of coffee and when it's done I'll show you the next step okay so it's stitched all those together and we can zoom in a little bit and you can see that it did a pretty good job it's a good looking aerial photo made from those but it's not geo-referenced and this is just the the preview image so we're going to hit next and this next option is to crop it and I've never really messed with that and so I think you could crop it down if you wanted to but I'm just going to leave it like this and we can crop it in our GIS or we don't need to crop it so then I'm gonna hit next one more time to get to export and you've got all these images are these options over here and right now I'm going to leave it at quality of seventy-five percent I think you can take that up to a hundred but I'm just going to leave it at seventy-five for now and then export it to disk and when I do that it's going to go ahead and create a JPEG of that stitch together panorama and we're done and so if I go and open that up you can see here's my JPEG and I can zoom in and it's got pretty good resolution but like I said we need to georeference this so let's go ahead and take this to arcmap and geo-reference it okay so now we've got our aerial photo stitched together we've got a Geo reference it and I'm gonna do that in arcmap so here i've launched arcmap and you can see I've already got a point shapefile loaded in of a few points these are ground truth points or control points these are spots in my area where I went out and I took the latitude and longitude coordinates using a GPS so these are known spots of known coordinates and so to show you what these coordinates represent I'm going to add a base map and just add art maps aerial imagery and you can see that this is the area and you can see that these points fall in known locations in the area that I'm mapping all right I know exactly where each of these points is and in fact I think I labeled them properly so if I click on the information for this point it you know it's the farthest west driveway column it's a column at the end of the driveway right so so I know that these are our known points which I can use to georeference my new image so I'm going to go ahead and get rid of this image and I'm going to load in the aerial image that we just stitched now I want to show you something before I do that here's that image we just created right this is the stitch together JPEG that we just created and just notice the file structure here we're going to come back to this in a second so I'm going to add that which is here and it's a large file so if you look down here it's going to take a few seconds to load it in okay so I get this warning which doesn't surprise me it says it's missing a spatial reference well that's the point that we're giving it a spatial reference so it doesn't surprise me so I'm gonna hit okay and that's why you can't see the image because it doesn't have a spatial reference and so if i zoom all the way out you know here's the image but it's not properly geo reference it's not properly oriented so if I go back I need to get that image to show up here where the control points are and I'm gonna go ahead and zoom out just a little bit because I know that the image covers a little bit greater area than these points and so I need the geo referencing toolbar so I'm going to come up here and right-click find the geo referencing toolbar and turn that on and so you see that the geo referencing toolbar recognizes that hey that that JPEG that's something you might want to to georeference so it's already chosen you but you got to choose the correct image right here okay so to get it to show up where where we're looking at right now we just had to go to this tab and hit fit to display and now now we brought it in to where we can see it but it's not properly geo reference and it's not properly oriented you know this North is sort of running to the to the left here I went north to run up so before I geo reference it I want to orient it so it's pretty close if you try to georeference it and it's not oriented very closely usually the software has trouble with that and so I'm just going to take this button here which is rotate and I'm just going to click it and I'm going to grab it and rotate it about 90 degrees and that's pretty close to reality okay that's pretty much north up it's close enough now that I can geo-reference this image all right and so to georeference the image what I'm going to do is I'm going to use this tool right here to add a control point so I'm going to choose that and this gives me a crosshairs and I'm going to click on a spot on my unreferenced image on my aerial photo and then I'm going to click on the control point that represents that portion of the image right so I know that this when we already looked at this one let's let's start with this one we we looked at the information on this point and we know that this is the column at the end of the West driveway which is about here and so I got to start with the unreferenced point so I'm going to zoom in so I get a good look at where that spot is on my new image and you know these are big images and it taxes the video card so it takes a little while at least on my machine but you can see you know a pretty good high-resolution image right and so this is the column that I'm talking about right here so I'm going to click on that and then give it a second because of the big image you want to make sure that it is registered that as a point and so once this loads back in you can see that now I've registered that as a point so I'm going to go ahead and zoom back out so I can find the actual control point that represents that area which is here so I'm going to zoom in on that control point so I can get a good accurate click and I'm going to click on that control point an art map will shift that and you see now that we've shifted this picture so that that one point is exactly where it should be in our aerial photo which is pretty slick right but that's not enough because we have to uh we have to kind of resize and move this photo around a little bit to make sure the whole thing is geo-referenced and so we need you know usually at least I have four of these four is probably the minimum the more points the better and so our next point that we want a geo reference we don't want to go rock right next to the existing point we want to kind of try and find a spot that's a little bit further away so I'm going to pick this point up here which I know this point represents this tree so I got to start with the unreferenced image and so that's sort of the center of this tree right here and then I'm going to zoom out and then I'm going to zoom in on where that tree should be which is right here on this yoke on this point and there you go and so it shifted and now that trees in the right spot but it held the first spot where it should be and so it's warping the and resizing the photo to get these points to fit where they're supposed to fit so let's do this one in the lower right I know I know this one in the lower right is the corner fence post what you see right here and I'm gonna come up and that should be there and so fits pretty good and so now our image is looking real good but our our last point this last point should be a fence post here near the barn and you see they're off a little bit still and that my computer's got to catch up and so this post should be where that dot is but again click it make sure make sure it registers it as a point before you go and click on the known the control point so now I can come over here and click there and it'll give it a little bit of a adjustment ok and so now this photo is pretty well geo-reference now I say pretty well because look this last one you see that these are not lining up perfectly but that's you know that's maybe a meter off more or less and so I'm going to right click and zoom to this layer zoom to the photo layer and now we have that image resized and geo-referenced and it's pretty good now here's the thing is it's geo-reference right now but if we shut down it won't save that right we need we need to save it in such a way so that when we open this up later it will already be geo-referenced and so there's a couple ways to do that one that works pretty well is i'm going to go to geo referencing and just do update geo referencing and when i do that you see all those control points disappeared and a lot of things grayed out and then the next thing I want to point let's go back to the file to the folder where I showed you and see now we've got three more three new files there right here's the original jpg but now arcmap created a couple more files and that's what arcmap is going to use to help geo reference this file right and uh and so there you go ok so now you have that jpg and it's geo reference properly so we can make it look a little bit better if we go to properties and then we look at symbology and then if you come here to display background value and then leave this a zero zero zero when you hit apply you see you make that black border go away and there you have it and so now to show you that this JPEG is indeed georeference what we're going to do is we'll start and make a new blank map I'm not going to save this existing one and so I got a new map I'm just going to go ahead and add the jpg right from the start and there it is and I can maybe add a base map imagery and let arcmap add its own imagery and we'll see how well they line up and they look pretty good let me go ahead and get rid of that black border again so display a background and there you go you can see the roads are lining up and and that figure is geo-reference so that wasn't too bad and probably it's actually faster than the online ones but most importantly it didn't cost us a dime other than the arcmap license which we already have so let me don't get any questions ok so now what do I do if I don't have any GPS control points a lot of times you can't collect control points with your GPS maybe the area is inaccessible maybe the canopy is too enclosed and you can't get a good GPS signal is there any way that we can geo reference this new image that you just stitched together and I've got a couple of ways that I think work pretty well the first is to just use the base map in ArcGIS and so within our GIS you have that base map imagery that is already geo-referenced now this imagery is not going to have as high res Ellucian as your new image and consequently it's not always easy to find matching control points but if you can find spots on the existing arcgis base map that you can match up to the image that you just stitched together then you can use that to georeference your new image so let's take a look at that okay so here I have arcmap and I've added an ArcGIS base map and this is you know roughly the area where my my stitch together image is going to be so you might have to find some other kind of a file that's near your area so that you can get arcmap to zoom into the area where your image is but once you get there now we can look for places that we can match up with our new image and you need some level of precision here so I could look for like corners or things so let the corner of the barn here would be really good the corner of this pond wouldn't be bad some of these trees might not be bad although the shadows may get a little tough you know road intersections are usually pretty good but might be a little wide for this example you zoom out a little bit and see if there's anything else I can find here you know you again this fence post or something might be good but so let's try this so I'm going to go ahead and add my new stitched image okay and again I get a warning that there's no spatial reference which I already knew and so I'm gonna do the same thing I got my geo referencing toolbar it's set to my new station image so I'm gonna fit to display and again it's not oriented properly so I'm gonna go ahead and rotate it this one goes about 90 degrees when we go back a little bit that's too far yeah a little further I know this road sort of runs east to west so that's what I'm looking for so that's pretty close and so now I'm just going to go ahead and geo reference like I did before one problem is the points on the base map are underneath my image but that's not really a problem so I'm going to start with my tool and I want to start with the corner of this bar and so I'm going to zoom in on it again we always click on the new image first the one that needs to be referenced and I'm going to choose here this northwest corner of the barn and then I need to find where the barn is on the arcmap base map so I'm going to go ahead just uncheck my image and then I can look on the arcmap base map and so then I'm going to go ahead and try and zoom in on it a little bit and I can match that up pretty well and now when I turned my image back on you see that's that's pretty good so let's find something else now let's let's see if we can't do this corner fence post again and so that's gonna be about right there now I'm going to turn off my image is in the mouth a little zoom out till I can see all right and so when I'm panning I'm folding down see on the keyboard and that allows me to pan and now I'm going to zoom in and you see the problem with using the arcgis base map is it doesn't have quite the resolution so it's kind of hard to see where you need to click this looks to be about that corner so there we go i turn my image back on and now we zoom out again and of course every time you zoom in and out art that's got to go fetch new maps and so it slows you down a little bit and how about let's use the corner of the driveway that should show up no that's kind of in shadows how about the corner of the neighbor's driveway that'll work so we're going to go ahead and look at the neighbor's driveway and that's belt right here yeah we'll take that one and that's going to correspond to about here alright but you see what I mean bites you don't always have the cleanest points but you can get pretty good now I wonder if I can't use that tree I could probably use this tree again get pretty close so I'm gonna kind of pick the center of this tree turn off my image and then go to the center of that tree there you go and if we look go ahead and turn off the dark border and you see the roads or not as one leaned up you know so it's not as good as the first one we did but that's not that and so we can go ahead and update the display and then it will be geo-referenced for further use now find a way that you can geo reference this new image that you stitched together is to use the coordinates that are already built into your images so whatever your drone takes a picture it labels that picture with a set of coordinates and we can assume that these coordinates represents the center of the image and they're stored in what's known as an XS tag and so we just need to get these coordinates from these images and use them to georeference your new image now this takes a few steps and it's a little bit more complicated but it does work so the first step is to extract those coordinates from the images and again keeping with the idea that we're trying to do this on the cheap we're going to use a free program called exif tool and this is not a very user friendly program all right but you only need to use it for a short time and you only need to use a couple of specific commands and this will extract all the coordinates from all your images and so what you want to do is you want to get this XF tool dot exe it's a very small program and make a copy of it and put a copy into the same folder as your images now you don't want to launch it you don't want to double-click it we're just going to run this from a command line so you need to know where this this program and your images are stored so go to file explorer find this folder and then copy the entire path of this folder by right clicking on it and choosing copy as text and and we're going to use this here in the command line okay here's where I downloaded that program access tool and it looks like I'm using version 10 point 6 9 maybe so you can just google that you it'll find it and so here's the executable and I'm just going to copy it so ctrl C and now here's the folder that's got all my original images from my Dremel and I'm just going to ctrl V and there I've made a copy and put it in with my images all right now I'm going I need to know the name of this folder so I'm just going to come up here and right click copy addresses text and now that's on my clipboard and I can use that here in a second now to get the command line we're going to go to the start button and type CMD and that's going to launch the command prompt then we need to switch to the drive which contains your images and your image folder so just type that drive letter and a colon and hit return and that will switch it to the drive and then you have to change to the directory which contains your images and so you use CD your change directory and then space and then you'll paste that folder address that you just copied so just use control V to paste that folder address and then hit return and that should switch you to the folder that contains the images and the XF tool program and this is what you need to do so you can run that program okay so we need to get a command prompt so let's go down here to start click on it and then when that comes up go see an MD and we see the command prompt and that's what we're looking for and so now we need to get to the drive which contains the folder with the images and on my computer that's f so f coma and return and so now we're on that proper Drive and then you'll remember that we copied the address of the folder so it should still be on the clipboard so if I go to control V there's my folder now you notice that it added the F again so that's going to be a problem so let's go ahead and backspace and get rid of those and then when I hit return and oh that's wrong that's wrong that's wrong that's wrong what I need to do is go CD and then that address so change directory to that address and so again I need to get rid of this F and it's colon and then hit return and so now I've switched to the proper folder so now I can run that program now to run the program you just want to type the following command that you see here and all this does is it launches XF tool and it extracts the coordinates and it will extract the coordinates from each image and save them all into a CSV file and so this is what we want okay so we just need to type that command in order to run the program and extract the coordinates and all I did was just copy it and I'm gonna paste it here at the command prompt so control V and I don't even have to hit returner and I don't think I think it's running so let's see what happens and there you go and so it looks like it read 255 images and and extracted the coordinates from each of those so I'm gonna come over here to the file and you see we've got this new file here called long dot CSV if you go back and look at the command prompt you see that long dot CSV was what we were going to name this file so let's go ahead and see what's inside here and so if you look here I'm going to resize all of these and so you see you've got the source file so here's each of those images and here's the file name so really the same thing and it's got the image size but here you've got the latitude and the longitude and so great that's what we need but this format's not going to work in arcgis so we're going to do a little work to clean this up and that'll be next so you notice that the coordinates are not in the format which we can use in arcmap they're in degrees minutes decimal seconds but we need things in decimal degrees so we need to convert them before mapping them in arcgis so let's do that now okay so we've got these ugly coordinates we need to turn into some good looking coordinates so we can use first thing I'm going to do doesn't get rid of this row but I don't want it let these headers next thing I'm going to do is I'm going to take this latitude and I'm going to copy it because I need the space and I want to keep an original copy here in case I screw everything up so here I get the latitude that I need to turn into decimal degrees so I'm going to select this column I'm going to go up here to data and then text to columns and so I'm going to choose a fixed width I've got to separate these numbers out from you know degrees and the little minute sign little second sign and the easiest way to do that is no fixed width so if I go next you see it did a pretty good job of picking these apart but I got to get rid of these other symbols so I'm going to add another break there and I'm going to add a break there and now I've got the numbers pulled out so I'm going to hit finish and so you see it took that one column and it split it into several columns but some of these columns have the numbers I need you so this column is going to be where my new coordinates are going to go and I'm going to label it lab and so I need to take these numbers and convert them to decimal degrees so I'm going to start with the seconds which is right here and so I got fifty three point zero eight seconds and there are 60 seconds in a minute right and so this is almost one minute I need to convert this to decimal minutes so I'm going to take this excuse me I'm going to start a formula so I'm going to go equals and then I'm going to take this cell and divide it by 60 and I'm going to hit return and so you see my value is 0.88 so 53 seconds is about 0.88 of a minute right that makes sense okay and so now I can combine this with the minutes to get decimal minutes so I'm just going to come up here and change my formula I'm going to go ahead and wrap this in parenthesis so it doesn't get messed up and I'm going to add this to the cell that contains my minutes and when I hit return now my decimal minutes is 37.8 8 so it's 37 minutes fifty three point oh eight seconds is equivalent to thirty seven point eight eight minutes right beautiful but I need decimal degrees right now I have degrees decimal minutes so I need to do this one more time well I've got thirty seven point eight eight minutes and there are 60 minutes in a degree so let's go ahead and divide this by 60 again so I'm going to come up to that formula I'm going to wrap the entire thing in parentheses and I'm going to divide that entire thing by 60 and when I hit return you see I get zero point six three and so 37 minutes 53 point zero eight seconds is equal to zero point six three of a degree and again this should make sense to you right if I had thirty minutes that would be half a degree this is a little more than thirty minutes and it's a little bit more than a half a degree so there you go I've converted my minutes into a decimal degree but I already have 36 degrees so again I need to add these together so I'm going to come up here to my formula wrap the whole thing in parentheses again and I'm going to add all of that to the cell which contains my degrees and when I hit return there you have it I've got I've converted my degrees minutes and decimal seconds which you can see here 36 degrees 30 then it's fifty three point oh eight seconds is equivalent to thirty six point six three one four one degrees and so that's decimal degrees and that is what we need to map an arc map and we also needed to do this again because this format you know that's got a mix of numbers and letters and symbols arcmap would never play well with that and so now that I got that formula I'm just going to double click this little square the little box here in the corner double click it and that gets copied all the way down and it's beautiful and I'm gonna go ahead and save before I lose any of this and I'm gonna go ahead and while all those cells are selected I'm going to ctrl C to copy them and then I'm gonna go to the Home tab and choose paste values and so now if I click on one of these cells you see it's not a formula anymore I put the actual number values in there and that's just that'll be a lot easier you know I don't have to worry about changing something and messing this up but also I have to do that so I'm going to go ahead and get rid of all these columns just so mark map doesn't get confused by anything save it up now I need to do the same thing but for longitude so let's go ahead and copy my longitude column over and now I'm going to go data.txt a column fixed width separate out those symbols hit finish now my new column I'm gonna label lawn and I need to start by getting my decimal seconds so this is giving my decimal minutes and now I need to take that whole thing and add it to my existing minutes all right so now I have decimal minutes but I need to wrap this in parenthesis in two eyes like 60 and that's my equivalent decimal degrees and I need to then add all this so I need to wrap this in parenthesis and add it to the number of degrees I had and there's my decimal degrees however we're in the Western Hemisphere and the Western Hemisphere longitude is negative and so we need to go ahead and multiply this whole thing by negative one so let's wrap it in one more set of parenthesis and go times negative one and hit return and now that's the correct longitude so I'm going to double click copy that down ctrl C to copy come over here paste values see that I've got numbers instead of a formula get rid of all these useless columns now hit save and now I've got a file that I can use in arcmap now that we have a CSV file with all the coordinates for all your images let's go ahead and map them so we can see the exact center of each of your images so we'll just take that CSV and create a series of control points okay so now that we have our CSV file of control points from the images we've launched arcmap let's go ahead and add that file that's a long CSV and we need to display those points in XY form so display XY data and it's picked out the fields that we just created the x field is longitude the y field is latitude we need to tell it the coordinate system which will use the wgs84 and we hit OK and this warning is fine and so there you go and so you can see that this is a grid and each of these points is where the drone took a picture and to make sure that this is in the right spot we'll go ahead and add the base map image and you see that we're in the right spot and so now we have a series of control points and each of these control points is associated with one of our images we took for the drone and if we click on any one of the points you see which file that point came from and so once we find useful control points we know exactly what file we're going to use now that we have all these control points let's just kind of look and find four or so that will work four control points so we want them spread out across the new image you know sort of one in each corner and we also want to find ones that will likely be easy to recognize in the new image so look for control points that are you know on near or around on top of some sort of distinguishing feature anything that will be able you'll be able to find in the new stitched image so I've changed the color of the control points and made them yellow make them a little bit easier to stand out on this background so I need to find four or so in the corners that will make good control points for my new image and so I'm going to start down here in the southwest corner and I need to find a point here that I will be able to find on my final image and there's a lot of points here that are sort of in the woods and these are going to be tough although you know it would probably be doable I'm gonna try and make it easy on me I'm gonna find something that'll they'll stand out I see this point right here it's right at the edge of the woods and right on the road it's in the southwest corner this might be a good one so I'm going to check the info on this this point right here and you see that that point is for image 1:07 okay and so now I'm going to go back to where the images are stored and I'm going to find image 1:07 and here it is right here and so the center of this image is where that point is and so if you look about where the center of the image is you can see that it's kind of where I expect it's it's near the edge of the road it sits next to the woods and so you know this image that you're looking at now this has been incorporated into the stitched image and so this is exactly what I should be looking at when I look at the stitched image and so I should be able to find this area on that stitched image which means that I can relate it to this point that I just found and I can use that as a control point and so that's what we want to do so I'm gonna go ahead and do that and then I'm gonna try and find three more like this and then we can figure out where exactly these points lie on these images now that we know what control points we want to use we want to find the center of the images for those control points the control points should be labeled with the file from which they came so you should be able to find the original images for each of your control points so you want to find these images and then you want to somehow mark the center now you can sort of estimate where the center is but if we're trying to be precise let's mark the exact center because we assume that's exactly where the coordinates for that control point should fall and you can use Photoshop or something I use a program called which is GNU image manipulation program this is like an open-source version of Photoshop and it's very powerful and all I'm going to do is I'm just going to mark the center of each image and then that's going to tell me what to look for when I'm geo referencing my stitch together image so I want to mark the exact center of these images that I'm using for the control points and so I've got a gift here and so I can show you how to do this in and you can probably figure out an easy way to do this in any sort of image manipulating program so I'm gonna go ahead and open up that's file picture number one zero seven is what I'm working with and so pull that up here and and now you gotta be careful because sometimes the images aren't oriented the way you expect depending upon which direction the drone was turned or which direction the drone was flying these may or may not be in the proper orientation and so if you want to be able to recognize it in arcmap you want to rotate it to get the proper orientation which I I actually had to do to this image earlier and that's it's rotated properly now so I need to find the exact center of this image and so again the way I can do that as I can go to image guides a new guide by percent and so it's going to put in a vertical guide at 50% and when I hit OK you see I get this nice line that bisects it and so now if I do that again image guides new guide by percent switch to horizontal also 50% and so where those two intersect that is the exact center of this picture and that is exactly where that control point should sit and so this is what I can use to georeference my final image so I can just leave this open I want to save this because I have to do this a few more times so I'm going to use my image my screen capture program and you can get any you know screen capture program you want this one is called printscreen I use it I really like it anyway so I'm just going to screen capture that and I've got a Word document open here and I'm going to go ahead and just paste that and then I want to remember what file it was and so that was 107 and so if I need to go back and look for that file again but now when I'm looking for this spot you know when I'm geo referencing my final image I think come and look and I can see exactly where the center of that you know where that point should lie and so I need to do this a few more times to get a few more control points and then what we're ready to go now that I have a good idea of where my control points should fall I can just use the same techniques I used before to georeference this new stitched image okay so that was a lot of work however we should be able to georeference our image now and let's try and do that so I'm going to go ahead and add the stitched jpg and again we get the warning that there's no spatial reference which we know and again we want to set this to our stitch JPEG and she's fit to display to get it close and again we want to rotate it a little bit to get it kind of close a little bit more that's pretty good okay so just like before we just need to use the control points and match them up with this image and so let's find our first control point so you remember that this one right here was one that we were going to use or actually you don't know that this is one that I was going to use and it's for image 144 and I found the center and I saved it and so this is image 144 and so you see the center and so you see where that point should go and if i zoom in a little bit okay so my control point should go sort of right where this stain ends right kind of at the very bottom of that stain and so I'm going to come here and I'm going to get my control points tool and I need to zoom in on that portion until I can see that staining really well let's zoom in a little more and since this stitched image was made from these other images I should be able to find these spots pretty easily and so there's that stain and so let's look again so sort of right in the middle or that dark turns to light right at the edge I'd say right about here is where that control point should be so I click and let it go ahead and register that as a point and we're slowing down cuz we've got these big files and I'm gonna go ahead and zoom out a little bit zoom out a little bit more zoom out a little bit more gotta find that point back there there's that point there I missed it let's drag a little there this is that control point right this is point 144 and I marked exactly where this point should go so I should you should snap right to it and now we've put our stitched image right there and if we go back to where we work the center that's pretty darn close I think and so that's how we can use this to georeference our final image so let's go ahead and do another one so I'm gonna find one the opposite corner and I think the one that I wanted to use let's go and look here okay so if I look at this point here that's for picture 190 that's not it I have a problem I need point two zero three as to what I was looking for oh I don't what problem is I see what problem is I'm looking for the point based on my stitched image my sniffs image is not geo-reference I need to look for the point based on the baseline image this over here is where I need to be looking I was looking on the new image and it's not right yet but the baseline is good you know the base image is pretty close so this is the the point that I want right here you understand and I click on that and that's point 203 that's the one I'm looking for okay so now let's go back and look at that image 203 and so right there is where the the control point should go and so let's go back to arcmap and now we zoom in on the new image and we look for this spot and so if we go back and look at the mark image you see we got the burn pile here we've got kind of this brown spot if we kind of there's there's a little lighter green there so what you're seeing here is you're seeing why this technique is a little tougher because we find these spots there might not be you know where our control point is might not be very easy to see on the final image but we can do our best so I kind of have an idea here where that point should be zoom in now see there you go now of course my computer's got to catch up again and there you can sort of see that light stuff and you can see this brown patch here and that burn pile so I'm thinking that control point is going to be right about here let's go ahead and look one more time and you see that so horizontally you see in this light patch there's a little bit of green tree or something and we're just south of that and we're just at the edge of that burn pile so if I come back I'm gonna get my control point tool I'm just the edge of this burn pile you know what I see what's going on let's see what's going on I don't see what's going on these images or not I think that image needs to be rotated a little is that right what am I missing here our world let's see if I can drag this into the same screen your that so I'll put these next to each other now so what's happening is okay so you know I'm looking at one image and looking for the center of that one image your mosaic here is a bunch a images stick to stitch together and so when it's stitched together and use maybe some different images and so that's why things don't look like they don't look exactly the same I think that's what's going on here and so if I compare these two you do see that the burn pile has about the same shape here and you can kind of see some of this lighter stuff so I think this is what I'm going to do is I'm just going to have to kind of look and I say right about there is where my control points going to be so I'm going to click on that and now I'm going to zoom back out and this point is this point 203 over here and it kind of snaps to that and there you go so sorry for the confusion but you see the limitation of this method is it's a little bit harder to find your spots so I'm going to go ahead and finish this up using my last two spots I won't make you suffer through that but you get the idea you get the idea of how we can use the coordinates from the existing images and use those to try to georeference our final image and it works pretty well and that's it so let me know if you've got any questions

Channel: Timothy Spier

Views: 7,826

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Id: bKFbYSYbdhk

Length: 59min 38sec (3578 seconds)

Published: Sat Jun 08 2019