A solution? (including resolution) - Re: [GRASS-user] Re: Help: Converting a raster map between locations (from wgs84 lat / long to UTM)

[Corrado]

On Tuesday 04 November 2008 19:17:23 Glynn Clements wrote:
> Corrado wrote:
> > does the r.proj resample the raster?
> >
> > The documentation seems to suggest you have to use g.region -m, .... or
> > may be I did not understand it properly.
>
> Like most raster commands, the output from r.proj has bounds and
> resolution which match the current region settings.
>
> For each cell in the current region, r.proj reverse-projects the
> cell's centre to the source region. It samples (or interpolates) the
> input map at that point, and stores the sampled/interpolated value in
> the corresponding cell in the output map.


I am not sure I understand the recommend process then.

If r.proj matches the region of the output by resampling, why do we have to 
set the same region in the input and output locations? As long as the ouput 
location is set to a subset of the input location, then r.proj should then be 
able to project (and resample). Is that right?

On the other hand, what method does r.resample use? is it cubic? if that is 
the case, the result should be more or less the same as r.proj method=cubic.

What do you think?

Best,
-- 
Corrado Topi

Global Climate Change & Biodiversity Indicators
Area 18,Department of Biology
University of York, York, YO10 5YW, UK
Phone: + 44 (0) 1904 328645, E-mail: ct529 at york.ac.uk