Re: [GRASS-user] Upscaling an elevation model
the algorithm of this addon is based upon the paper mentioned in the manual. >Or is it simpler what you suggest? there is maybe no "unique" upscaling algorithm. - best regards Helmut -- Sent from: http://osgeo-org.1560.x6.nabble.com/Grass-Users-f3884509.html ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Upscaling an elevation model
* Helmut Kudrnovsky [2019-02-02 08:17:03 -0700]: NikosAlexandris wrote Dear "elevation" experts, I am looking for ways to upscale a 5m resolution elevation model. The upscaled models will be subjected to a series of trials using `r.watershed`. Derivative products will be inputs for soil erosion modelling. In our wiki page about Interpolation [0], `r.resamp.stats` [1] is presented as the only tool to resample a raster map to a coarser grid. However, `r.resamp.rst` [2] also performs resampling to a lower resolution. [0] https://grasswiki.osgeo.org/wiki/Interpolation [1] https://grass.osgeo.org/grass76/manuals/r.resamp.stats.html [2] https://grass.osgeo.org/grass76/manuals/r.resamp.rst.html While the target is to somewhat maintain "geomorphometric consistency" across the different (coarser) scales, which tool is recommended? For `r.resamp.stats`, would you recommend a resampling method other than 'average'? Thank you, Nikos ___ grass-user mailing list grass-user@.osgeo https://lists.osgeo.org/mailman/listinfo/grass-user you can see https://grass.osgeo.org/grass74/manuals/addons/r.valley.bottom.html "[]The MRVBF index assesses the flatness and lowness of terrain over multiple scales and DEM resolutions[...]" how it's there. Ahoy Helmut, resampling takes place through the helper function `refine()` [0]. Then, if I understand it right, you use 'average' (for `r.resamp.stats`) only when upscaling [1]. [0] https://trac.osgeo.org/grass/browser/grass-addons/grass7/raster/r.valley.bottom/r.valley.bottom.py#L391 [1] https://trac.osgeo.org/grass/browser/grass-addons/grass7/raster/r.valley.bottom/r.valley.bottom.py#L595. You use 'bilinear' when downscaling (the slope and the "percentile" that is), right? [2, 3]. The "percentile" (number of lower elevation points / total number of points in surrounding region), is part of the algorithm. [2] https://trac.osgeo.org/grass/browser/grass-addons/grass7/raster/r.valley.bottom/r.valley.bottom.py#L591 [3] https://trac.osgeo.org/grass/browser/grass-addons/grass7/raster/r.valley.bottom/r.valley.bottom.py#L601 Can we use this tool to say "look, our resampled elevation maps are similar"? But then, I'd need to run this for each resampled map and compare the outputs (say MRVBF or/and MRRTF)? Or is it simpler what you suggest? Nikos ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Upscaling an elevation model
NikosAlexandris wrote > Dear "elevation" experts, > > I am looking for ways to upscale a 5m resolution elevation model. The > upscaled models will be subjected to a series of trials using > `r.watershed`. Derivative products will be inputs for soil erosion > modelling. > > In our wiki page about Interpolation [0], `r.resamp.stats` [1] is > presented as the only tool to resample a raster map to a coarser grid. > However, `r.resamp.rst` [2] also performs resampling to a lower > resolution. > > [0] https://grasswiki.osgeo.org/wiki/Interpolation > [1] https://grass.osgeo.org/grass76/manuals/r.resamp.stats.html > [2] https://grass.osgeo.org/grass76/manuals/r.resamp.rst.html > > While the target is to somewhat maintain "geomorphometric consistency" > across the different (coarser) scales, which tool is recommended? > For `r.resamp.stats`, would you recommend a resampling method other than > 'average'? > > Thank you, Nikos > ___ > grass-user mailing list > grass-user@.osgeo > https://lists.osgeo.org/mailman/listinfo/grass-user you can see https://grass.osgeo.org/grass74/manuals/addons/r.valley.bottom.html "[]The MRVBF index assesses the flatness and lowness of terrain over multiple scales and DEM resolutions[...]" how it's there. - best regards Helmut -- Sent from: http://osgeo-org.1560.x6.nabble.com/Grass-Users-f3884509.html ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Upscaling an elevation model
Dear "elevation" experts, I am looking for ways to upscale a 5m resolution elevation model. The upscaled models will be subjected to a series of trials using `r.watershed`. Derivative products will be inputs for soil erosion modelling. In our wiki page about Interpolation [0], `r.resamp.stats` [1] is presented as the only tool to resample a raster map to a coarser grid. However, `r.resamp.rst` [2] also performs resampling to a lower resolution. [0] https://grasswiki.osgeo.org/wiki/Interpolation [1] https://grass.osgeo.org/grass76/manuals/r.resamp.stats.html [2] https://grass.osgeo.org/grass76/manuals/r.resamp.rst.html While the target is to somewhat maintain "geomorphometric consistency" across the different (coarser) scales, which tool is recommended? For `r.resamp.stats`, would you recommend a resampling method other than 'average'? Thank you, Nikos ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
