[GRASS-windows] Georectify problems

[Moritz Lennert]

On 05/12/08 11:36, Ken Mycock wrote:
> Moritz & List members
> 
> I've now cracked the bad format issue - accidentally double clicking a 
> point on the target map to give the east-north reference puts two sets 
> of coordinates into the point file. That is one line ends up with one xy 
> point followed by two east-north points, hence the bad format.  I'll log 
> a bug report on this relatively small aspect.
> 
> Correcting this allows i.rectify to run to completion.  For my test 
> image, it reported over 3.5 million cells created for each of the three 
> colour channels, which is as expected.  However, displaying the 
> resulting georectified raster in the target mapset shows large single 
> colour blocks arranged in the expected portion of the target region - 
> north 5 blocks cover over 1 km and east 8 blocks cover about the same 
> distance, so the region is covered by 40 cells, not the reported 3.5 
> million.
> 
> Any suggestions what I'm doing wrong this time?

You need to set the desired resolution and extent in the target location 
(g.region).

Did you run i.rectify from the command line or via the georectify GUI ? 
If the latter than until (including) 6.3, this ran i.rectify with the -c 
flag, meaning that it only rectified the portion of the map that lies 
within the current region of the target location. Since 6.4, there is a 
flag allowing you to chose whether you want this.

If you ran from the command line and didn't use the -c flag, then just 
try running g.region rast=YourMap and redisplay ("Zoom to computational 
region").

Moritz