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?
Thanks for your help.
Best Regards,
Andreas
___________________________________________________________ Gesendet von Yahoo! Mail - Jetzt mit 1GB Speicher kostenlos - Hier anmelden: http://mail.yahoo.de
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
Hi Markus,
Markus Neteler schrieb:
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.
If you want to apply only linear stretch etc., load the vector
map directly into the target location and then use v.transform.
Markus
Thanks for your help. I did solve it with v.transform. Here is the
description how I exactly did it:
1) create a new xy location and Import the pixel image. Then create an image group and create a pointsfile based on this image. Save the points file from within i.points.
2) Import the vector map into the temp xy location. Make sure that your vectors start also at the same coordinates eg. x=0 and y=0. Check it by displaying the image first and then the vector.
3) Export with OGR into a shape file or one of the other types.
4) Import the vector map into the target long./lat. location, but for this vector map use the -o option in the OGR that ignores the
regions setting of your current region.
5) Use v.transform and the pointsfile from your x,y location to
rectify your image. Unfortunately this way only a 1st order tranformation is possible. But better than nothing.
6) Voila I have it. Maybe it is just enough to skip steps 2) and 3) and directly load into the target location.
Kind Regards,
Andreas
___________________________________________________________ Gesendet von Yahoo! Mail - Jetzt mit 1GB Speicher kostenlos - Hier anmelden: http://mail.yahoo.de