GEOG 490/590

GIS Programming

Exercise 7: Vector Analysis

This exercise lets you practice the use of vector data in spatial analysis. The exercise covers the two vector analysis lectures we had this week. The topics include:

1. Vector Geometry
2. Spatial Query and Selection Set
3. Spatial Join
4. Vector Buffering
5. Vector Overlay

You can use the sample code (Ex7_CodeSample.txt) for this exercise. You will need to use serveral point, line, and polygon shapefiles for this exercise. You can download sample data here.

Create an ArcMap add-in and copy and paste the sampe code into an event can could trigger the individual procedures (e.g., a button on a dockable window). Or, you can copy the code to a new class and call the individual procedures from the event control.

1. Before you can debug the program, you need to add the required references and import the namespaces to your project first. Please use online help to figure out which references and namespaces need to be added.
2. The sample code gets the data from layers added to ArcMap. Please add the layers to ArcMap before executing any code. Some layer names are hard-coded in the program. They are: aoi_v.shp, aoi_streams.shp, and stream_points.shp. The names of output shapefiles are also hard-coded in the program. Please read the sample code for these file names.
3. Try the following tasks on individual procedures.
   • ShapeGeometry(): calculate the total area of all polygons in the aoi_v shapefile; calculate the distances among the centroids of the aoi_v polygons.
   • CreateSelectionSet(): perform queries on numeric and text fields.
   • CreateSpatialQuery(): different SpatialRel values.
   • SpatialJoin(): using layers of different geometric types to perform different spatial join methods.
   • BufferDemo(): perform buffering on selected features only (see the code in the GetSelectionSet() for the method to get the selectset of a feature layer).
   • VectorOverlay(): try clip. dissolve, merge, and union methods of BasicGeoprocessor.