[GRASS-user] Problems running g.gui.gcp

[Moritz Lennert]

On 22/10/15 16:25, Johannes Radinger wrote:
> Dear GRASS users,
>
> Today I wanted to try the georectification tool g.gui.gcp in GRASS 7 for
> the first time. I was basically following the description on the GRASS
> wiki (https://grasswiki.osgeo.org/wiki/Georeferencing). In particular, I
> have a photograph from my camera with known reference points which I
> load into an unprojected XY location. My target location should also be
> a XY location as the picture is taken from a "virtual" coordinate
> system. Inside my target XY-location I try to open g.gui.gcp and select
> raster, and the location and mapset where my photograph is stored. When
> I want to click next I get following error/message: "You must select a
> valid location and mapset in order to continue" and I can't proceed with
> the rectification. Just this GUI message appears, no error/warning in
> the grass console etc. I am puzzled how to interpret that? What is wrong
> with the location/mapset? The mapset I've selected is existing (I can
> select it from the dropdown menu). I tried to select any other
> location/mapset but receive always the same message.


Georectification is for georeferencing to a projected system. It does 
not make sense to georeference to an XY-location.

I see two options for you:

- Import you image directely into the target region and use r.region to 
adjust its boundary coordinates
- Define your own projection system to fit your needs.

Moritz