[MUSIC] Hello everyone, and welcome back. In this lesson, I'm going to show you a few more vector data concepts by really emphasizing how vector data is built on the concept of point locations and connecting them with edges. So, to begin with, we're just going to zoom in on Lake Malawi down here in the eastern corner of Africa, and I'll use a bookmark. And I'm going to create some features right now. Now I'm not going to show you all the details of how to create features. We'll do that later in this class. So if you really want to know and follow along, just wait til later in this class and there will be a lecture on how to do that. For now, we're just focusing on how vector data is structured. So first, we can represent lakes as a point, we just generalize them all the way down to a point. And I can put down a point and call it Lake Malawi, and we have our point. And on the map there, we can label that point so that it shows up and we have that representation. So if I make it nice and big, we can see Lake Malawi here. So we can represent vector data as just a point, and we can get that point's latitude and longitude if we want to into fields. But we know that that point has a set of coordinates, so that's how we place it on the map. Now, that part might seem obvious, there are points, but if we zoom down here to the Shire River, I'm going to zoom in even a little closer. We can also make lines, and these too are basically built out of points, these point locations. So if I switch to this line feature class I'm going to edit this line here. I click and I see a point on the map. And then as I move my mouse around it's trying to make a line that fits there for me. So I can create another point here, and it just puts an edge, a line, in between those two points I made. And it's fitting the line to match my points that I'm putting down. So every time I click, it's creating a point and that most recent point is red. That's the point that's active and it's trying to connect to. And I click again and it moves along, and it cements that previous point in the green there. And I can keep going, creating this line out of points. So, once again, we're generalizing this river. We're taking this three-dimensional thing and basically making it nearly one dimensional, but kind of two dimensional here, and turning it into this narrow line that curves through its area. And that line is completely constructed out of points, and ArcGIS does that work of connecting the points, wherever I place them, with edges or lines in between them. So really foundationally, we're coming down to the vector feature information being built out of these point locations. Even though, when I finish this feature here, it becomes just a line like anything else we've seen. We can see, as we just did that, it's actually built by point locations. Now, polygons are the same. So if we go back to seeing Lake Malawi and I switch to digitizing that, I'll turn off that point feature, and I can start digitizing the polygon. And again, we see that same concept of that red dot. And I can move around, and it's trying to make a line that connects my cursor to the most recent point I laid down. But once I click that second feature, it then has two lines. It's trying to fill an area for me. And when I click that third one, it starts showing me the polygon's current filled area in the color of the polygon in the layers symbology. And so I can kind of click through all this, really quickly digitizing the lake here. I'm going to be very sloppy, but again, I'm going to show how to do this all later in this class and you'll get lots of practice with it. And you'll be very sick of it at some point, because digitizing is what a lot of new GIS people spend a lot of their time doing. So now I have this polygon and I just created it again with this clicking around the boundary. And we have all these points that actually define the locations of this polygon and then it connects those points with edges, and then it fills the area for us. And the actual information that we're providing is this string of coordinates, these point locations. But we are now saying that, as a data structure, we infer information about everything that's inside of this area, that's what making a polygon does for us. So I can again finish this, and I got a polygon. And just like before, I can open up the attribute table and I can give it some information in here. I can say that this is also Lake Malawi and, Make that a little more visible. And what I want you to get reminded of here is that each feature class has many features in it, and those features are defined in the way that we just described. But that each feature also has an individual record and that, in fact, this feature information here, this polygon, is just one field in this attribute table. It's just one bit of information about the polygon. The rest of it is this tabular information, this attribute information in this individual's record. But the polygon we created is stored effectively in this shape field, and then the rest of the information is in other fields. And we have this single object here. Now, the point is also an object model. It's just that the feature information that we have happens to be a point instead, and same with the line. But they all have an attribute record, and you can think of it as the feature having an attribute record or as being a member of the attribute record. Either way, whichever's most convenient for you, but know that both are kind of true. Okay, so that's it for this lecture, it's very brief. I just wanted to demonstrate to you the vector data model and its basic concepts, which are that we build everything based on these x and y point locations. We set down the coordinates on the map and then we do things with them. Sometimes we just leave them alone as a point and have attributes, and other times, we say, okay, connect this point to this other point in a line. Or connect these points together and fill the area and create a polygon for me, and we'll generalize information inside of that area in one object. So I hope that that helps you visually understand how the vector data model works a little more, and that you'll take that with you as you go into the rest of the class, as we create more data. Okay, see you next time.