[GRASS-user] Re: GRASS-user] Help with reprojection

[Hamish]

Hamish wrote:
> - create a simple xy location
>     (lat/lon location will not allow north > 90, and your image while
>      still not geo-referenced will go to 8100)
> - run r.region to set n,s,e,w bounds to 90,-90,180,-180
> - run g.setproj to rejig the location into a lat/lon one.

umm, that might not work -- r.info will still know the map is XY even
if the location is changed to lat/lon.

> - check resolution is correct (nicely "0:01:20") with r.info.
> - zoom to area of interest. you probably do not want to reproject
>   entire planet. after zooming check resolution is preserved,
>   (g.region -p, maybe with "g.region res=0:01:20 -a" after zoom to fix)
>   and run "r.mapcalc cropmap=fullmap" to perform the crop.
> 
> then from the lambert location run r.proj to pull the
> cropped image across.
> 
> there are some examples of this process in the GRASS wiki,
> look at the "Global datasets" page.

the above issue should be covered there; also check the mailing list
archives.

so your "easiest" solution is to create a "world file". see the GDAL
JPG or GeoTiff format import page, or do a web search for instructions.


Hamish