[GRASS-user] define a region by 2 epsg

[Alex Mandel]

How far into the second UTM Zone does your region go? If not far and the
distortion is acceptable you can reproject 1 into the other.

Otherwise you need to find or create a Projection that does a better job
of covering your region. A UTM projection is unlikely to be a good
candidate in this case. Do you care more about preserving Area or
Distance measures (that will help you pick an appropriate projection).

So, no, you can not use 2 EPSG codes at the same time, you have to
convert the data into a common projection.

Thanks,
Alex

On 03/16/2016 08:10 AM, Mourad Boutouchent wrote:
> I'm working on watershed hydrology, then I went to obtain drainage direction, accumulation zones, streams system and elementary watersheds of a study area. However I work on an area which belong to 2 EPSG (EPSG 3313 and EPSG 2972). 
> 
> I download all the SRTM tiles of the study area and have filled the voids. I merged these tiles and projected the result in the EPSG 2972 (initially WGS84). Of course, a part of the DTM has negative EAST coordinates which cause errors when assinging region and running r.watershed and r.water.outlet.
> I tryed to work in WGS84 but still r.water.outlet does not work.
> 
> Is it possible to define a region with  two EPSG? How achieve r.water.outlet with success
> I'm quite locked...Any help ?
> 
> ------------------------------------------------------------------------------------
> B.Mourad
>  Laboratoire de Mathématiques Informatique et Applications
>  Université de Guyane
>  Tél : 06 63 81 50 29
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