Incorrect geometries obtained for DXF

[meier]

There is no support for reading 3D geometries through DXF. For instance, a simple example demonstrates the example - You get POLYGON EMPTY when you insert (POLYGON ((0 0 0,0 0 1,0 1 0,0 0 0))) into a dataset and try to read it back, but not with POLYGON ((0 0 0,0 1 0,1 1 0,0 0 0)). The issue is that same 2D points (same X and Y coordinates) result in empty geometries. In the case of 3D geometries with same X and Y coordinates, but different Z coordinates, the same thing happens.

[Even Rouault]

I think we can close this ticket. It was based on a wrong assumption on the content of a HASH object