Dear grass users,
does anyone know which is the algorithm applied to a raster map when changing the resolution using g.region res=XXX?
If I have a 1m resolution raster map and I change the region resolution to 2m using g.region, the new 2x2-cell values are an average of 4 cells in the 1x1-map?
thanks,
silvia
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Silvia Simoni PhD
DICA - Department of Civil and Environmental Engineering
Universita' di Trento
via Mesiano 77, 38100 Trento, ITALY
tel. +39 0461 882610
fax. +39 0461 882672
e-mail: silvia.simoni@ing.unitn.it
Silvia Simoni wrote:
does anyone know which is the algorithm applied to a raster map when
changing the resolution using g.region res=XXX?
If I have a 1m resolution raster map and I change the region
resolution to 2m using g.region, the new 2x2-cell values are an
average of 4 cells in the 1x1-map?
Raster maps are sampled based upon the region; no interpolation or
aggregation is performed.
If you want interpolation or aggregation, you need to perform an
explict resampling step with r.resamp.interp, r.resamp.rst or
r.resamp.stats.
--
Glynn Clements <glynn@gclements.plus.com>
Silvia Simoni wrote:
but I still do not understand your sentence: "Raster maps are sampled
based upon the region"; which is the sampling technique? In other words,
given a 1x1 dem, and changing the region resolution from 1x1 to 2x2, which
effect produce on the values in the 2x2 dem? How are they determined?
Nearest neighbor? 4-cell-arithmetic average?
Nearest neighbor.
--
Glynn Clements <glynn@gclements.plus.com>