[GRASS-user] Help with DEM, Raster and Vector export to VTK / Paraview

[Vincent Bain]

Hi David,

(besides your latest private message, I post a reply on the mailing
list)

If I understand correctly, your concern is about extracting vector and
raster data from GRASS in order to add them to a Google Earth 3d view
(I'm not familiar with the latter, sorry).

I guess my very rough addon v.out.blend can only be of little help for
you, except that you may explore its content, the code is quite well
commented; the main issue for you is that the script performs a
shrinkage+translation to output so it can fit blender units system
(blender has a weir behavior when working with high values cartesian
coordinates). If you need to preserve original coordinates, you can run
the attached modified script, where it is possible to specify dx, dy,
dz, scale values.

On the other hand what may be interesting for you is the ability of the
script to turn a 3d point cloud (e.g. extracted from your DEM) to a TIN.
The script performs it via pvpython, but there are multiple
alternatives...

Another thing I would suggest you is to have a try at the blenderGIS
blender addon:
https://github.com/domlysz/BlenderGIS

If you are already familiar with blender, it surely will be much easier
and faster to compose your different scenes (layered raster/vector data)
from within blender then export results as .dae files.

Hope this helps,
Vincent.


Le lundi 07 mars 2016 à 07:43 +1100, David Wright a écrit :
> Hi
> 
>  
> 
> I would be grateful for some tips on the steps to export a DEM with,
> raster and vector layers to the vtk format for visualization in 3D
> Paraview.  
> 
>  
> 
> My ultimate objective once in paraview is to export the model into a
> file format that can be converted into a dae file format so it can be
> loaded as a 3D model in google earth.
> 
>  
> 
> Specifically I wish to drape different images on a dem  and visualise
> them in google earth above the surface of the area concerned. There
> may be a better method to achieving this from Grass however output to
> VTK seems to be the best option as a starting point.
> 
>  
> 
> My datasets include a clipped area taken from an Aster DEM, matching
> aerial image rasters and vectors (ie clipped to the same shapefile)
> that are using the Geographic Projection EPSG code 4326.
> 
>  
> 
> I have been able to import these into Grass and visualise them using
> NVIZ no problems.
> 
>  
> 
> I have searched extensively for help on the steps to export rasters
>  to vtk and attempted exporting rasters using both r.out.vtk and
> r3.out.vtk but in Paraview I either get a blank window or a single
> line I Paraview that can be rotated in 3d.
> 
>  
> 
> If someone could advise the steps or point me to some online resources
> setting out the steps, I would be most grateful.
> 
>  
> 
> I wonder if my Aster DEM is in the correct format as it is. Or does it
> need converting to a different format first – ie 1 3D voxel format. 
> 
>  
> 
> Any help would be very much appreciated.
> 
>  
> 
> Regards
> 
>  
> 
> David
> 
> 
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
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