[GRASSLIST:5706] ground control points for image rectification

Dear listers,

I'm trying to rectify Landsat 7 satellite images on the
basis of topographic map.
The Landsat images are already rectified and referenced,
but in regard to my purposes not accurate enough.

so far:

1. I imported the topographic raster map in a location with gauss-krueger projection.

2. I imported the Landsat data in another loaction with utm projection.

3. Out of these data I built an image group and targeted this on the location / mapset which include the topographic raster map.

4. Then I tried to use i.points for finding ground control points (GCP).

This does'nt work very well, because it is really hard to retrieve the GCPs, placed on the topographic map, in the satellite image.

Does anybody know a more adequate way to find GCPs in satellite images?

Thanks,

Grit