[GRASS-user] Resample DEM to larger cells

Rich Shepard rshepard at appl-ecosys.com
Tue Oct 1 14:48:43 PDT 2019

On Thu, 26 Sep 2019, Markus Neteler wrote:

> For an overview, there is:
> https://grasswiki.osgeo.org/wiki/Interpolation
> As usual, text snippets for manuals/raster.html are appreciated (via PR in
> https://github.com/OSGeo/grass/blob/master/raster/rasterintro.html
> ). There is an easy "edit" symbol for casual contributors.
> Maybe some info should be transferred from the Wiki page to rasterintro.html.


I've worked on other analyses waiting for a missing DEM file to become

Rather than resampling I'll stick with the 1m DEMs for now; perhaps will
find that aggregating to 5m would be better.

For this project, Stefan, the topographic analyses are geomorphic, not
hydrologic. I've a vector line map of the river network and for the intended
audience and project objective that's quite adequate.

However, I have a question (for anyone to answer) about working with this
basin topography.

There are 70 individual raster maps within the mask of the basin's watershed
boundary. Am I correct that speed-issues aside, I need to run r.buildvrt so
I have a single map as input to modules such as r.info (to identify the
highest elevation), r.slope, and others? While I understand that a mask
limits analyses to its area that is based on a single map extending beyond
the mask and not a collection of 70 'tiles'. Am I correct?

Are there alternatives to a virtual raster for situations like this?



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