GeosGeometry doesn't support empty 3d points

[Nicolas Noé]

I need to create an empty 3d point using GeosGeometry, but it appears the z dimension gets lost in the process:

In [1]: from django.contrib.gis.geos import GEOSGeometry

In [2]: g = GEOSGeometry('POINT Z EMPTY', srid=4326)

In [3]: g.ewkt
Out[3]: 'SRID=4326;POINT EMPTY'

In [4]: g.hasz
Out[4]: False

I'd expect g.ewkt to be 'SRID=4326;POINT Z EMPTY' and g.hasz to be True. As a consequence, I can't assign it to a 3d model field.

I see the correct behavior if I use a non empty 3d point:

In [13]: g_non_empty = GEOSGeometry('POINT Z (1 1 1)', srid=4326)

In [14]: g_non_empty.hasz
Out[14]: True

In [15]: g_non_empty.ewkt
Out[15]: 'SRID=4326;POINT Z (1 1 1)'

I also tried creating the same feature using EWKB (0x0101000080000000000000F87F000000000000F87F000000000000F87F is a 3D empty point), but the third dimension is also lost here, just like in the first example.

[Mariusz Felisiak]

Thanks for the report, however, this looks like an issue in GEOS not in Django itself (see e.g. ​https://trac.osgeo.org/geos/ticket/1005). Django doesn't do anything special with the WKT. I'd try to report/discuss this in GEOS bug tracker.