[GRASS-dev] importing & projecting

[Moritz Lennert]

On 18/09/15 13:34, Paulo van Breugel wrote:
> I imported raster layers in a projected mapset, while the data layers
> were in latlon. I used the r.in.gdal from the menu (i.e., not command
> line), importing all geotif files in a directory.
>
> I would have assumed that GRASS would throw an error as the layers were
> not in the correct projection. Instead GRASS just imported the layers,
> projecting the layers 'on the fly'.
>
> A very convenient option , but I wonder if it shouldn't be an option
> that should be explicitly selected by the user?

I very strongly agree and I think that such an important decision should 
have been discussed on the ML (if it was, sorry, I must have missed it). 
The relevant changes, AFAICT, are r65751 (v.import) and r65917 (r.import).

I don't have a strong opinion on this, but I think that there is some 
advantage to GRASS telling the user that the file she is trying to 
import is in a different projection than the location and that explicit 
use of v./r.import would necessary.

Now the import wizard just silently imports anything without even 
informing the user that reprojection is happening. This does not always 
make sense and is a potential path to many disasters...

Projection handling is not easy, but IMHO it is one of the strengths of 
GRASS to force the user to think about it. I agree that r./v.import are 
a very nice convenience, but their use should at least result from a 
conscious decision, not out of ignorance...

Moritz