[Gdal-dev] SHAPE 3D support?

[Markus Neteler]

Dear list,

from a customer we received a 3D SHAPE file which,
according to the customer, contains 3D buildings.

I tried to import the map with v.in.ogr into GRASS 
which worked well except for the 3rd dimension.
Using shpdump I found:

shpdump SaviglianoZI_CN4410.shp | head
Shapefile Type: PolygonZ   # of Shapes: 24

File Bounds: (  393994.326, 4944791.347,0,0)
         to  (  394305.613, 4945138.609,4.2794e-08,nan)

Shape:0 (PolygonZ)  nVertices=9, nParts=1
  Bounds:(  394243.242, 4944978.999, 4.2794e-08, -1.79769e+308)
      to (  394298.322, 4945091.844, 4.2794e-08, -1.79769e+308)
     (  394259.825, 4945091.844, 4.2794e-08, -1.79769e+308) Ring
     (  394298.322, 4945079.994, 4.2794e-08, -1.79769e+308)
     (  394287.595, 4945045.143, 4.2794e-08, -1.79769e+308)
     (  394296.197, 4945042.495, 4.2794e-08, -1.79769e+308)
     (  394276.652, 4944978.999, 4.2794e-08, -1.79769e+308)
     (  394244.045, 4944989.036, 4.2794e-08, -1.79769e+308)
     (  394258.615, 4945036.368, 4.2794e-08, -1.79769e+308)
     (  394243.242, 4945041.101, 4.2794e-08, -1.79769e+308)
     (  394259.825, 4945091.844, 4.2794e-08, -1.79769e+308)

[...]

It seems that the 3rd dimension is missing in the file (say,
it's unused). According to 
 ogr/ogrsf_frmts/shape/shpopen.c
OGR should grab the 3rd dimension properly.

Someone else was showing me the file in ArcGIS. It was flat unless
the "extrude" function was used which transfers values from a 
selected numeric column (e.g., height) to the third dimension.

It seems that we either have to program a 'shp2dto3d' program
or to program v.extrude in GRASS 6?
Suggestions welcome - maybe someone in this community already
solved the problem...

 Markus

PS: Importing 3D DXF/DWG in GRASS 6 works out of the box
    supposed you have compiled it with opendwg-toolkit.