[gdal-dev] Issues with shapefiles with Z values?

[Greg Troxel]

David Strip via gdal-dev <gdal-dev at lists.osgeo.org> writes:

> I'm sending this to the gdal-dev  on the assumption that gdal underlies QGIS's creation and export of shapefiles. Let me
> know if this is a bad assumption and I'll redirect to qgis-dev

It's a good assumption.

My advice for you to figure out your issues is not quick, but:

  Start reading about "3D POINT" and "POINTZ" as simple features.

  Get clear on 3D vs 2.5D and how those terms are or aren't the same and
  how they show up in vector representations of geometries.  I am fuzzy
  on this myself, but given what you are doing it would be better if you
  were very clear on it :-) I think this is about the difference between
  the Z being part of the geometry and the Z being an attribute of a 2D
  geometry.  But I also think there is some non-uniformity of
  terminology in various places.

  Use ogrinfo.  Really dig in.  You can get metadata about the layer and
  the contents.