I'm trying to validate some polygons that are on planes with
Too few points in geometry component at or near point
from shapely.geometry import Polygon
poly1 = Polygon([(0,0), (1,1), (1,0)])
poly2 = Polygon([(0,0,1), (1,1,1), (1,0,1)])
poly3 = Polygon([(1,0,0), (1,1,1), (1,1,0)])
# Too few points in geometry component at or near point 1 0 0
The problem is that
shapely in fact ignores the z coordinate. So, as far as shapely can tell you are building a polygon with the points
[(1,0),(1,1), (1,1)] that aren't enough to build a polygon.
See this other SO question for more information: python-polygon-does-not-close-shapely.
IMHO, shapely shouldn't allow three dimension coordinates, because it brings this kind of confusions.