[GRASSLIST:6956] Re: georeference vector map and transform from xy location to long/lat projection

[Markus Neteler]

On Mon, May 30, 2005 at 09:53:01PM +0200, Andreas Rathgeber wrote:
> Hello all,
> 
> I have a outside of GRASS digitized vector map (original map was 
> image with distortion and some rotation) loaded into an XY 
> location. This location also contains the original image.
> Now I want to georeference both maps into my target location that 
> has a long. / lat. projection.
> I've created a pointsfile based on the original image. I have no 
> problem to georeference the image into my target location with 
> the target projection.
> Where I struggle is the georeferencing of my vector map into the 
> target location.
> 
> I was thinking about v.proj, v.transform to do it.
> With v.transform and the pointsfile from my image I was able to 
> remove the distortion and do the rotation. But this only leads to
> a much reduced size and the question how I get the vector map 
> into my target location. The v.proj seems not possible as in an 
> XY location no PROJ_INFO is available - and what certainly make 
> sense when one understand how the georeferencing of vector maps 
> is done ;-)
> 
> Can someone point me to the correct order of the steps I should 
> perform?

If you want to apply only linear stretch etc., load the vector
map directly into the target location and then use v.transform.

Markus