National Center for Geographic Information and Analysis
Unit 34 - The Polygon Overlay Operation
- Author(s): Unit 34, CC in GIS
- White, Denis
- Editor(s): Goodchild, Michael F.
- Kemp, Karen K.
- et al.
Building on the simple algorithms presented in the preceding two units, this unit discusses one of the most complex operations of vector GISs—polygon overlay. Traditional motivations for and the general concept of polygon overlay operations are described and the algorithmic approach explained. Issues arising from a mismatch of computer precision and data accuracy are illustrated with examples and mitigation measures presented.