[GRASS-user] Reprojecting and resampling raster map

stephen sefick ssefick at gmail.com
Fri Jul 31 16:12:27 EDT 2009

Thank you all for your helpful comments

On Fri, Jul 31, 2009 at 3:04 PM, Glynn Clements<glynn at gclements.plus.com> wrote:
> stephen sefick wrote:
>> When you reproject a raster map to a new location does it
>> automatically re-sample it to the regions resolution.
> The new map is created using the destination region. The original map
> is read at its native resolution, regardless of the source region.
>> I have a 10x10
>> meter grid in albers equal area projection.  I have reprojected it
>> into UTM zone 17 res=50.  This is a base flow index map bfi.  Does
>> grass resample the map to 50x50m?
> For each 50x50m destination cell, r.proj reverse-projects the cell's
> centre coordinate to the source projection, and samples the input map
> at the projected coordinate. Exactly how it samples the map depends
> upon the method= option (nearest, bilinear, cubic), but the sampling
> or interpolation is based upon the raw source map, without any further
> resampling.
> --
> Glynn Clements <glynn at gclements.plus.com>

Stephen Sefick

Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods.  We are mammals, and have not exhausted the
annoying little problems of being mammals.

								-K. Mullis

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