[GRASS-user] Multidirectional hillshading scripts / addons?

GRASS GRASS user
1

Hi,
I am trying to create a hillshading effect using DEM rasters similar to ESRI multidirectional hillshading, but I am unable to get anything in. grass to perform as good as ESRI (or even gdaldem multidirectional shading).
I am hoping someone in this group has some scripts /addon/tips that I can try.

So far I have tried the following on a few DEMs ( from 3m to 100 m grid sizes).

  1. gdaldem multidirectional hillshading : It’s not grass based, but so far has performed better than other grass options : with the parameter zfactor between 1 and 10. But it does not seem to be quite as good as ESRI.

  2. Following code is based on some old discussion on this email list.(Its seems to exaggerate the hills and valleys more than I would expect)
    https://gist.github.com/amcox/b54d65f08fe4448840462901fd6350d4

  3. Other variants of hillshading like r.skyview : Tried with several parameters but it seems to be inferior to gdaldem (It seems to be a ‘washed out’ version of the multidirectional. hillshading).

Thanks,
HB

2

Hi,

Not sure about grass gis, but have you tried the multidirectional option when styling a raster as a hillshade in QGIS? See https://bnhr.xyz/2019/01/22/hillshade-in-qgis.html.

Cheers,

Paulo

On Fri, Feb 16, 2024 at 11:20 PM B H via grass-user <grass-user@lists.osgeo.org> wrote:

Hi,
I am trying to create a hillshading effect using DEM rasters similar to ESRI multidirectional hillshading, but I am unable to get anything in. grass to perform as good as ESRI (or even gdaldem multidirectional shading).
I am hoping someone in this group has some scripts /addon/tips that I can try.

So far I have tried the following on a few DEMs ( from 3m to 100 m grid sizes).

  1. gdaldem multidirectional hillshading : It’s not grass based, but so far has performed better than other grass options : with the parameter zfactor between 1 and 10. But it does not seem to be quite as good as ESRI.

  2. Following code is based on some old discussion on this email list.(Its seems to exaggerate the hills and valleys more than I would expect)
    https://gist.github.com/amcox/b54d65f08fe4448840462901fd6350d4

  3. Other variants of hillshading like r.skyview : Tried with several parameters but it seems to be inferior to gdaldem (It seems to be a ‘washed out’ version of the multidirectional. hillshading).

Thanks,
HB

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3

WhiteBox is another option (there is a QGIS plugin)

https://www.whiteboxgeo.com/manual/wbt_book/available_tools/geomorphometric_analysis.html#MultidirectionalHillshade

Carlos

···

Prof. Carlos Henrique Grohmann
Institute of Energy and Environment - Univ. of São Paulo, Brazil
Editor-in-Chief - Brazilian Journal of Geology

http://carlosgrohmann.com
https://spamlab.github.io/

http://orcid.org/0000-0001-5073-5572

Can’t stop the signal.

4

Hi HB,

Here is one more:

r.shaded.pca - Creates relief shades from various directions and
combines them into RGB composition.
https://grass.osgeo.org/grass8/manuals/addons/r.shaded.pca.html

Best
Markus

On Fri, Feb 16, 2024 at 11:20 PM B H via grass-user
<grass-user@lists.osgeo.org> wrote:

Hi,
I am trying to create a hillshading effect using DEM rasters similar to ESRI multidirectional hillshading, but I am unable to get anything in. grass to perform as good as ESRI (or even gdaldem multidirectional shading).
I am hoping someone in this group has some scripts /addon/tips that I can try.

So far I have tried the following on a few DEMs ( from 3m to 100 m grid sizes).
1) gdaldem multidirectional hillshading : It's not grass based, but so far has performed better than other grass options : with the parameter zfactor between 1 and 10. But it does not seem to be quite as good as ESRI.
2) Following code is based on some old discussion on this email list.(Its seems to exaggerate the hills and valleys more than I would expect)
https://gist.github.com/amcox/b54d65f08fe4448840462901fd6350d4
3) Other variants of hillshading like r.skyview : Tried with several parameters but it seems to be inferior to gdaldem (It seems to be a 'washed out' version of the multidirectional. hillshading).

Thanks,
HB
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