ercise 1: Creating GIS data—points lines and polyg A very common method of creating vector data is to physically create these files through on-screen digitizing. In Arc, you will need to create the shapefiles first (as blanks) and then fill in the features (points, lines, polygons). To do this we will use ArcCatalog to create the blank files then bring them into ArcMap to draw the shapes. 1. Start ArcCatalog and navigate to your folder. Select “New” and “Shapefile” and “polygon” DON”T close this window yet. 2. In the coordinate system box you’ll see it is empty. Click “Edit” and “Import” 3. Navigate to your folder (ON V:) and select the campus1.img file click “Add” 4. The information for the campus1.img projection should be in the box. Click “OK” 6. Click “Ok” again to create the shapefile (you don’t need to check any of the additonal boxes). 7. Repeat these steps for a point and a line feature 8. When you’ve created the 3 files, start ArcMAP and add the campus1.img image to your blank map
Transcript
Exercise 1: Creating GIS data—points lines and polygons
A very common method of creating vector data is to physically create these files through on-screen digitizing.
In Arc, you will need to create the shapefiles first (as blanks) and then fill in the features (points, lines, polygons). To do this we will use ArcCatalog to create the blank files then bring them into ArcMap to draw the shapes.
1. Start ArcCatalog and navigate to your folder. Select “New” and “Shapefile” and “polygon” DON”T close this window yet.
2. In the coordinate system box you’ll see it is empty. Click “Edit” and “Import”3. Navigate to your folder (ON V:) and select the campus1.img file click “Add”4. The information for the campus1.img projection should be in the box. Click “OK”6. Click “Ok” again to create the shapefile (you don’t need to check any of the additonal
boxes).7. Repeat these steps for a point and a line feature
8. When you’ve created the 3 files, start ArcMAP and add the campus1.img image to your blank map
1. Add the 3 new shapefiles and the campus1.img image to the map. You’ll notice the shapefiles are empty.
2. Start an editing session (Editor pulldown menu) and make sure your polygon layer is the “target” file listed and that “Create New Feature” is the “task”.
Remember: Tool-----Task-----Target when editing or creating features.
3. When you have the editing session started, click the down arrow next to the pencil icon. This is the selection of tools you can use to create and edit your new shapefile. For now stay with the sketch (pencil) tool.
With the sketch tool you are going to draw polygons by hand. Every click will drop a vertex into the map. The more vertices you have, the more detail in your polygons.
NOTE: Square features may only need 4 vertices so there is no need to add 40. However, some irregular features like the pond will require several. You can go back and add, delete or move vertices to your shapefiles OR to others if needed.
4. When you have created your first polygon. Right click on the layer and open the attribute table. Here you will see that Arc created a table entry for your new polygon. It will do this for each one you draw. In future labs we’ll see how to merge these together if needed but initially it is better to have them as separate entries.
5. To add a field to the table go to “options” and “add field” NOTE: The edit session will need to be off for this to work so for now just create your polygons, points, lines (Stop editing and SAVE EDITS OCCASIONALLY then re start).
6. When you have drawn your features go to the tables and add the appropriate fields such as AREA, PERIMETER, LENGTH, Class (or land use etc.) Latitude (Y) and Longitude (X).
NOTE: Number fields are “Double” format while classes will be “Text”
Part 1 Assignment:
Create a basic landcover map for a selected area of the WCU campus using point, line and polygon features. Keep it simple but make sure it makes sense too. You’ll be going back to name these features and will be turning in a table. I’d suggest about 4-6 types of features at the most.
For each feature type (point, line, poly) open the attribute tables and add the following fields (go to “options, add field”):
1. Class (your system of classification) (format will be text)2. Area, length, perimeter, X, Y, as appropriate. (Format is “Double”)3. Other numeric (double) or categorical (text) as needed.
Naming your classes
Select all of your polygons for any given class, right click in the table ON THE CLASS COLUMN and select Calculate Values. Type whatever name you assign to those polygons. Repeat until all of your features are titled.
Calculating Length, Area, Perimeter, X and Y
First clear out any selected features (selection, “clear selection features”)
To add text to a table you can highlight the row(s) you want to fill in and right click on the COLUMN you need name or calculate and select “FIELD CALCULATOR” Numbers go in directly and text needs to be in “QUOTES”
To calculate AREA, LENGTH, PERIMETER and Lat/Lon right click on appropriate column. Select “Calculate Geometry.” Here you will be given a choice for Area, Length, Perimeter, X and Y coordinates. Just make sure you are right clicking on the appropriate column when you select.
To turn in : A single Layout with the following
1. The landcover map containing your point, line and polygon features
2. Legend, scale bar and N. arrow for your map window.
