arc gis期末复习考点第十二章

Chapter 12 Review Questions

1. Define a buffer zone.

A buffer zone is the area that is within the specified distance in a buffering operation.

2. Describe three variations in buffering.

The buffer distance can vary by the values of a given field. Buffering can be on either the left side or the right side of the line feature, instead of both sides. Buffer zones may remain intact so that each buffer zone is separate from others, or dissolved so that there are no overlapped areas between buffer zones.

3. Provide an application example of buffering from your discipline.

[A supermarket chain can buffer potential store locations with a buffer distance of 1 mile for demographic analysis.]

4. Describe a point-in-polygon overlay operation.

A point-in-polygon overlay operation uses a point layer as the input layer and a polygon layer as the overlay layer so that each point in the output is assigned with attributes of the polygon within which it falls.

5. A line-in-polygon operation produces a line layer, which typically has more records (features) than the input line layer. Why?

In a line-in-polygon operation, each line feature on the input layer is dissected by the polygon boundaries on the overlay layer. Therefore, the output has more records (line segments) than the input layer.

6. Provide an example of a polygon-on-polygon overlay operation from your discipline.

[An example of a polygon-on-polygon overlay operation is to overlay a land use layer on a soil layer in order to find the dominant soil type for each land use type.]

7. Describe a scenario, in which Intersect is preferred over Union for an overlay operation.

Every feature on an Intersect output will have attribute data from both of its inputs. Therefore, Intersect is preferred over Union if a project requires that attribute data be complete for each output feature.