[GRASS-user] export of a GRASS voxel to .VTK induces deformation

GRASS GRASS user
1

Here are the commands I used in GRASS 6.4 RC5 (under OSX Leopard) :

# computation of a 3d raster with z values from z() function
r3.mapcalc Z='z()'

# export to VTK format with top (the srtm DEM) and bottom (a flat surface)
r3.out.vtk Z output=./Z_3dg.vtk -s top=srtm30 bottom=bottom --overwrite

Instead of cutting into the GRASS raster 3d, the r3.out.vtk command deforms
the cells, so that computed z() isosurfaces are not horizontal (see image
grid_inversed_deformed_z below).
I expected top and bottom function of r3.out.vtk to cut into the model,
instead of applying deformation to fit the top and bottom. Am I right ?

http://n2.nabble.com/file/n4528866/grid_inversed_deformed_z.png

thanks for your reply,

cheers

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2

Hello,

Am Sunday 07 February 2010 12:53:23 schrieb yepri:

Here are the commands I used in GRASS 6.4 RC5 (under OSX Leopard) :

# computation of a 3d raster with z values from z() function
r3.mapcalc Z='z()'

# export to VTK format with top (the srtm DEM) and bottom (a flat surface)
r3.out.vtk Z output=./Z_3dg.vtk -s top=srtm30 bottom=bottom --overwrite

Instead of cutting into the GRASS raster 3d, the r3.out.vtk command deforms
the cells, so that computed z() isosurfaces are not horizontal (see image
grid_inversed_deformed_z below).
I expected top and bottom function of r3.out.vtk to cut into the model,
instead of applying deformation to fit the top and bottom. Am I right ?

The top and bottom options are only for fancy visualization purpose and work
as expected. They do not cut the volume. If you need to cut, try to use
r.to.rast3elev and use Paraview to remove the specific parts of the volume
(threshold filter).

Best regards
Soeren

http://n2.nabble.com/file/n4528866/grid_inversed_deformed_z.png

thanks for your reply,

cheers