R: [GRASS-dev] Reproject, change resolution and patch: doubts....

[Maciej Sieczka]

Marco Pasetti pisze:
Summarizing:
> 1) r.proj method=nearest
 > 2) r.resamp.rst
> Right?

Marco,

If you care about the accuracy very much:

# in ll/WGS84 location:
g.region rast=your_srtm_tile
r.to.vect -z in=your_srtm_tile feature=point out=your_srtm_tile_vect

# in your projected location
v.proj
g.region vect=your_srtm_tile_vect res=20 -a
v.surf.rst (or else)

Raster to vector followed by reprojecting the vector preserves the
original SRTM values perfectly in regard to their values and location
(given that you set the initial region correct). Also it lets you avoid
the distortion which takes place when reprojecting raster, due to
different grid spacing and skew of the source latlong and target
projected location.

Maciek

P.S.

Just for the record - it looks more like an issue to dicsuss on the
user ML.