Creating vector data by digitizing in ArcMap

it's important when you're first learning about GIS to understand the connections between the theory and the practice in other words I can tell you about things like geo databases and future classes and vector primitives and points lines and polygons and all that kind of stuff but really it's important to then be able to see well how is that implemented in the software or how does that work from a practical point of view so let's have a look at how that works all right so what we're gonna do here is digitize some existing features to create our own new feature class and I'm first going to create a new file geodatabase then i'm going to create a new feature class in that and then i'm gonna trace some objects from a satellite image so let's see how that goes okay so I've got a drive here which is my Z Drive or Z for my American friends but wherever you want to store this new data you just right click on the folder or the drive and just select new file geodatabase so remember this is just a container that you're using to store something and I like to give it a more meaningful name so in this case I'm going to be digitizing some features for an area in Toronto called Queen's Park so that's what I'm going to name it you can name it whatever you want and so now I have a new file geodatabase that's empty ok so then before I do anything else I want to add a base map to my empty map document I'm going to select imagery as my type of base map and just click Add so what's happening now is that arcmap is connecting to ESRI servers and the cloud it's downloading the image of a map into my map document just as you would see in Google Maps or any other kind of map service but now that's actually being fed into my map document from the internet so it starts out looking it's we were able to see the entire world and we'll just zoom in here to the area that I'm interested in mapping of course this could be anywhere but hey why not do a little bit of Toronto so now we can see the Great Lakes and this is Toronto here and you can do the same thing for whatever area it is that you're interested in mapping and you may notice that does this from time to time as you're zooming in and the reason is is that every time you zoom in it has to go and get that new more detailed zoomed in version of the web map from ESRI servers so it can sometimes there's a little bit of lag sometimes it's pretty responsive it just depends and if I continue to zoom in here I'm gonna find the area that I'm interested in so I'm using the zoom tool and I'm just going to pan over to find there it is the ER that I'm interested in so this is Queen's Park which is the the grounds or the area that the Ontario provincial government is based in you can see the building there that's the Ontario legislature and all I'm gonna do is they've got this nice oval-shaped Park around the grounds and I'm just going to digitize some features from that okay so what do I mean by digitizing and what is it we're looking at here and what does this all mean so this is a picture of the earth this is from a satellite image and this is a raster representation of the world in other words these are just pixels that show us what something looks like I can't select anything off of this I can't isolate it or work with it as it is right now what I'm going to do is trace some things into a vector version that I can then work with whatever way I want to to use it so you'll notice here in my table of contents it's got a base map I can turn that on and off just like I would any other layer and now that I have that I'm going to go back to the file geodatabase that I created and I'm going to create a feature class so I'm going to say new feature class and I have to give it a name so I'm going to say trees I have to tell it what kind of feature I want so there's a polygon line point there's some other ones there that you might get into a bit later but for now I'm going to represent my trees as points say next I'm gonna select the coordinate system that I want to use so for Toronto that would be nad 83 UTM zone 17 n they've may vary depending on where you are and what coordinate system you want to use that's something we'll cover in a different section but for now that's what I'm going to use next and we don't have to worry about the XY tolerance I'm just gonna go with the default for that and say next again now if I want to include my own column or field in my attribute table I can add it in here there's two that are added by default once called object ID and ones called shape those are used internally by the software you really don't need to pay too much attention to them right now but for example if I wanted to include something like type for the type of tree I could just put in the name of the column that I want to use with the field which is type and then I have different options here in terms of the type of field I could use so some are for storing numbers or texts or dates so for this I want it to be text and I can just say okay and I'm gonna go with the default there which was 50 characters long and say finish now sometimes you'll get a warning like this where it's saying wait a minute you just specified a different coordinate system which was UTM zone 17 that's a different coordinate system than the one that's being used to store the imagery that I'm using as my background for what I'm doing right now I don't need to worry about that again that's something we'll cover in this section on coordinate systems and projections and things I'm just going to say yeah that's okay don't worry about it and close it okay so now I have a new feature class in here that is being represented as a dot I can change that to something more fun so let's search for something related to trees there's a whole lot of different symbols available depending on how specific you want to be I could have Joshua trees great album by the way Chinese flame trees I'm just going to go away down here and pick one this one here that I think it's pretty easy to see and looks pretty good for for what I want to do so what I'm going to do now is create my own vector points for those trees so I need an editor toolbar to do that so I go up to customize toolbars and there's a whole lot of different toolbars available for various functions or things you want to do tasks so there's one here called editor I'm going to select that and now I have an editor toolbar that I can use to my editing I'm just gonna do some really simple stuff now just so you see how this works and if you want to create your own future classes quickly you can do this I want you to know how to do this from the very beginning I select the editor drop-down here and say start editing so with a database you have to tell it when you want to start editing and when you do want to stop editing so I've started editing and then something that may not be obvious if you haven't done this before is there's this little tab way on the end or button for create features and if I click on that it opens a new pane over here on the right saying create features so now if I select trees I can go to my map and you'll see that it's actually showing a little tree symbol by the cursor I hope you can see that and so wherever I click so on what I'm doing is I'm looking at the trees on the image I'm saying there's a tree there and if I click there that is now creating a tree symbol or a point in a vector format inside my future class that represents that tree and so I can do another one I could do one for here and here I can click all day long and create trees for these locations off of my image now of course it all depends on how much detail there is in the image that you're tracing off of how accurate you want to be I'm doing a pretty quick job here but I'm hoping that you get the idea and so this gives me a new set of points that I can actually do something with I can right click on the create features part the trees here and say properties and see what I've got here so I've got trees points I'm setting that up ok and I can go to the tab here and say attributes and so now when I select an object in my map so let's say I select this one here then I can type in the attribute for that particular tree so let's say that's a maple tree I can literally just type in maple and that now has the maple symbol I can go to the next one go to here so this is a different tree and maybe this is an oak tree I can go to a third one do all of these I'm just going to show you a couple of them see how this works go to here and maybe this is a beech tree okay and you can continue to do this as much as you need to and then I can say stop editing and when I say stop editing it will ask me well wait a minute don't you want to save your edits it doesn't save them automatically so you have to make sure to do this and I'm going to say yes please do save those and so now if I open the attribute table you can see that the attributes they typed in maple oak and beech are actually associated with those points in my digitized versions so now I can select that and see that particular point on the map I can do the same thing for oak and so on and that's all there is to it that's literally how you can create your own data you can easily create your own file geodatabase you can easily easily create your own feature classes and they can either be points lines or polygons and it's really that straightforward

Channel: Don Boyes

Views: 7,746

Rating: 4.9375 out of 5

Keywords: gis, arcgis, donboyes, introduction to gis, arcmap, digitizing, vector, arcgis desktop

Id: HgW91o3eUjI

Length: 9min 49sec (589 seconds)

Published: Mon Sep 16 2019