[GRASS-user] 3D raster remove voxels above DEM

[Moritz Lennert]

On 6/02/19 14:02, Francois Chartier wrote:
> Thanks Moritz
> 
> My goal is to summarize the steps for 3d interpolation at the end of the 
> process. it took me a year to get here and still have a few more steps 
> to do which i will contact the User list for.
> I am actually doing this as part of a 2nd master thesis with le Cnam in 
> Paris as continuing education, so i will formalize the process.
> 
> The voxels above the dem are not Null values in this interpolation as 
> the vvolrst interpolates the data within the full 'footprint' of the 
> g.region; is there a possibility to constrain the interpolation to in 
> between the DEM and lower surface, by setting a more customized Region 
> than a Block?

You could try r3.mask.

Moritz

> 
> 
> 
> On Feb 6, 2019 04:45, "Moritz Lennert" <mlennert at club.worldonline.be 
> <mailto:mlennert at club.worldonline.be>> wrote:
> 
>     Hi François,
> 
>     Thanks for sharing the solution you found. From your first mail it was
>     clear to me what these voxels above the DEM contained. NULL values ?
> 
>     It would be great if you could summarize all your experience working on
>     3D data in GRASS GIS in the wiki, at least by amending
>     https://grasswiki.osgeo.org/wiki/Help_with_3D with your additions or
>     corrections ? This would be very helpful many others.
> 
>     Moritz
> 
> 
>     On 6/02/19 03:46, Francois Chartier wrote:
>      > See attached screenshot, I was able to remove voxels above the
>     DEM and
>      > below bedrock surface using r3.out.vtk and selecting export as
>      > *pointdata (p)* not voxels.  If exported as a Voxel from
>     r3.out.vtk, the
>      > voxel file did not open properly in Paraview could be due to size of
>      > file. I changed option to export as points and it is working.
>      > grid resolution is 5 x 5 x 1 m over 4km x 4 km x 65 m thickness
>     approx.
>      > (actual thickness varies between DEM and top of rock).
>      >
>      > r3.out.vtk -p -s input=jan27551tens100 at Toronto
>     output=C:\Users\Francois
>      > Chartier\Documents\GeoModel\WorkingFile\Feb6_VTK_Pts
>     top=GTADEM at Toronto
>      > bottom=rock at PERMANENT
>      >
>      > Le mar. 5 févr. 2019 à 21:20, Francois Chartier
>     <fra.chartier at gmail.com <mailto:fra.chartier at gmail.com>
>      > <mailto:fra.chartier at gmail.com <mailto:fra.chartier at gmail.com>>>
>     a écrit :
> 
>      >
>      >     See attached screenshot, I was able to remove voxels above
>     the DEM
>      >     and below bedrock surface using r3.out.vtk and selecting
>     export as
>      >     *pointdata (p)* not voxels.  If exported as a Voxel from
>     r3.out.vtk,
> 
>      >     the voxel file did not open properly in Paraview could be due to
>      >     size of file. I changed option to export as points and it is
>     working.
>      >     grid resolution is 5 x 5 x 1 m over 4km x 4 km x 65 m thickness
>      >     approx. (actual thickness varies between DEM and top of rock).
>      >
>      >     r3.out.vtk -p -s input=jan27551tens100 at Toronto
>      >     output=C:\Users\Francois
>      >     Chartier\Documents\GeoModel\WorkingFile\Feb6_VTK_Pts
>      >     top=GTADEM at Toronto bottom=rock at PERMANENT
>      >
>      >
>      >     Le dim. 3 févr. 2019 à 16:42, Francois Chartier
>      >     <fra.chartier at gmail.com <mailto:fra.chartier at gmail.com>
>     <mailto:fra.chartier at gmail.com <mailto:fra.chartier at gmail.com>>> a
>     écrit :
> 
>      >
>      >         Hi,
>      >
>      >         I would like to remove voxels located at a higher elevation
>      >         than  DEM.
>      >         I have been trying r3.mapcalc without sucess.
>      >         Does the XY resolutions of both raster have to the same?
>      >         any ideas how to do this?
>      >         Thanks
>      >         Francois
>      >
>      >
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> 
>