[GRASS-user] Help with Georeferencing

[Moritz Lennert]

On 09/11/08 11:56, Matt B wrote:
> Hi Group,
> I'm slowly figuring out how to use grass but encountering the odd 
> problem. Actually, I haven't managed to get much done with grass at all 
> yet but I'm writing that off to the learning curve.
> At the moment I'm trying to georectify a stitched together google earth 
> image (I'm aware of the various legal issues that go with this and I'm 
> just using a few images to see if the work I want to do is feasible with 
> this type of data, if it is I'll look at purchasing data).
> 
> I've imported the raster into grass using gdal, it splits it up into 3 
> (RGB) files? and I can display it (in the wrong place at the wrong 
> scale). I also have the coordinates of the 4 corner points of the image 
> and those are what I'm using to georeference using the georeferencing 
> tool from the file menu.
> 
> I keep getting this error when I hit the "georectify" button in the 
> georeferencing tool:
> 
> Traceback (most recent call last):
>   File "/usr/lib/grass/etc/wxpython/gui_modules/georect.py", line 825, 
> in OnGeorect
>     self.SaveGCPs()
> TypeError: SaveGCPs() takes exactly 2 arguments (1 given)
> Traceback (most recent call last):
>   File "/usr/lib/grass/etc/wxpython/gui_modules/georect.py", line 825, 
> in OnGeorect
>     self.SaveGCPs()
> TypeError: SaveGCPs() takes exactly 2 arguments (1 given)
> 
> (python:11374): Gdk-CRITICAL **: gdk_window_set_geometry_hints: 
> assertion `GDK_IS_WINDOW (window)' failed
> 
> GRASS_INFO_MESSAGE(12418,1): Group <morondavaGE> has no target
> GRASS_INFO_END(12418,1)
> 


In which location are you running the georeferencing tool ? You have to 
run it in the target location, not in the location where you imported 
your original images.

Workflow:

- create two locations, one XY (unprojected) and one projected in the 
reference system you want to georeference the images into (AFAIR, Google 
Earth uses WGS84 lat-long, alias EPSG code 4326
- import images with r.in.gdal into the XY location
- in the projected location, run georectifying tool

Moritz

Moritz