The Spatial+ library supports the comparison of multi-polygon regions. Using pipCheckForRegionOverlap or pipCheckForRegionOverlapEx, you can compare two regions, where a region is defined as one or more polygons. The regions may be defined in terms of latitude/longitude or in user coordinates. This function does not require an object file, and can return one of the following results:
- No overlap – The two areas do not intersect in any way.
- Overlap – The two areas overlap, but the intersection does not equal either region.
- A contains B – The first area completely encompasses the second.
- B contains A – The second area completely encompasses the first.
- A equals B – The area contained by both regions is identical.
The following functions are used with pipCheckForRegionOverlap or pipCheckForRegionOverlapEx:
- pipInitializeOverlapCheck
- pipAddRegionAPolygon
- pipAddRegionBPolygon
- pipObjectFindFirstPolygon
- pipObjectFindFirstRect
- pipClearRegionAPolygon
- pipClearRegionAllPolygon
- pipClearRegionBPolygon
- pipTerminateOverlapCheck
The function pipObjectFindFirstPolygon compares an input region with regions in an existing object file. If any region in the object file intersects with the input region, the intersection type is returned. Possible intersection types are similar to those listed above for pipCheckForRegionOverlap. Use pipObjectFindFirstPolygon with the other object functions listed for use in PiP analyses.