[GRASS-user] v.what.rast and r.out.gdal questions: working with many rasters

GRASS GRASS user
,
1

I have a bunch of rasters
I want to extract average value each raster corresponding to vector polygons

Ideally, I would like to use v.what.rast BUT select only average (or a small subset) of the different stats that it allows.

Is that possible?

The only other route I know in GRASS is:

  • r.average using the rasterized vector as base raster, followed by
  • v.what.rast to extract to points representing the centroid of the polygons…

The final route i know is

  • to export GRASS raster to multiband GTiff
  • then use starspan
    -however on that route I was not able to export multiple rasters to a multiple-band GTiff…I would really like to know how to do that as well…

Thanks,
Vishal

–
Vishal K. Mehta, PhD
Scientist
Stockholm Environment Institute - US
133 D St Suite F
Davis CA 95616
www.sei-us.org

–
Vishal K. Mehta, PhD
Scientist
Stockholm Environment Institute - US
133 D St Suite F
Davis CA 95616
www.sei-us.org

2

I have a bunch of rasters
I want to extract average value each raster corresponding to vector polygons

Ideally, I would like to use v.what.rast BUT select only average (or a small subset) of the different stats that it allows.

Just use v.rast.stats, then drop (or simply ignore) the columns you don’t need.
I seem to remember someone mentioning on the list that the computing time to get all of the stats is about the same as the time for just one. So there’s nothing to gain by computing only averages.

··· 
-- 
Micha Silver
[http://www.surfaces.co.il/](http://www.surfaces.co.il/)
Arava Development Co.  +972-52-3665918