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

GRASS GRASS user
1

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

2

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@Toronto output=C:\Users\Francois Chartier\Documents\GeoModel\WorkingFile\Feb6_VTK_Pts top=GTADEM@Toronto bottom=rock@PERMANENT

Le mar. 5 févr. 2019 à 21:20, Francois Chartier <fra.chartier@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@Toronto output=C:\Users\Francois Chartier\Documents\GeoModel\WorkingFile\Feb6_VTK_Pts top=GTADEM@Toronto bottom=rock@PERMANENT

Le dim. 3 févr. 2019 à 16:42, Francois Chartier <fra.chartier@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

(attachments)

overall3dview.jpg

3

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@Toronto output=C:\Users\Francois Chartier\Documents\GeoModel\WorkingFile\Feb6_VTK_Pts top=GTADEM@Toronto bottom=rock@PERMANENT

Le mar. 5 févr. 2019 à 21:20, Francois Chartier <fra.chartier@gmail.com <mailto:fra.chartier@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@Toronto
    output=C:\Users\Francois
    Chartier\Documents\GeoModel\WorkingFile\Feb6_VTK_Pts
    top=GTADEM@Toronto bottom=rock@PERMANENT

    Le dim. 3 févr. 2019 à 16:42, Francois Chartier
    <fra.chartier@gmail.com <mailto:fra.chartier@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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4

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?

···

On Feb 6, 2019 04:45, “Moritz Lennert” <mlennert@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@Toronto output=C:\Users\Francois
Chartier\Documents\GeoModel\WorkingFile\Feb6_VTK_Pts top=GTADEM@Toronto
bottom=rock@PERMANENT

Le mar. 5 févr. 2019 à 21:20, Francois Chartier <fra.chartier@gmail.com

mailto:[fra.chartier@gmail.com](mailto:fra.chartier@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@Toronto
output=C:\Users\Francois
Chartier\Documents\GeoModel\WorkingFile\Feb6_VTK_Pts
top=GTADEM@Toronto bottom=rock@PERMANENT

Le dim. 3 févr. 2019 à 16:42, Francois Chartier

<fra.chartier@gmail.com mailto:[fra.chartier@gmail.com](mailto:fra.chartier@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

grass-user mailing list
grass-user@lists.osgeo.org
https://lists.osgeo.org/mailman/listinfo/grass-user

5

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@club.worldonline.be <mailto:mlennert@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@Toronto
    output=C:\Users\Francois
     > Chartier\Documents\GeoModel\WorkingFile\Feb6_VTK_Pts
    top=GTADEM@Toronto
     > bottom=rock@PERMANENT
     >
     > Le mar. 5 févr. 2019 à 21:20, Francois Chartier
    <fra.chartier@gmail.com <mailto:fra.chartier@gmail.com>
     > <mailto:fra.chartier@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@Toronto
     > output=C:\Users\Francois
     > Chartier\Documents\GeoModel\WorkingFile\Feb6_VTK_Pts
     > top=GTADEM@Toronto bottom=rock@PERMANENT
     >
     > Le dim. 3 févr. 2019 à 16:42, Francois Chartier
     > <fra.chartier@gmail.com <mailto:fra.chartier@gmail.com>
    <mailto:fra.chartier@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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