FAQ.rst

Frequently asked questions and answers

Are there references for the algorithms used by shapely?

Generally speaking, shapely's predicates and operations are derived from methods of the same name from GEOS and the JTS Topology Suite. See the JTS FAQ for references describing the JTS algorithms.

I used .buffer() on a geometry with Z coordinates. Where did the Z coordinates go?

The buffer algorithm in GEOS is purely two-dimensional and discards any Z coordinates. This is generally the case for the GEOS algorithms.