I have scanned in geographic and topo maps, imported them into an x,y GRASS
location using i.tape.other, and rectified them using i.points (keyboard input
of corners or other known lat/long points) and i.rectify.
Then I can scan in an aerial photo, import it into GRASS x,y using i.tape.other,
and rectify it using i.points (on highway intersections and stream bends) and
i.rectify, this time targeting the RECTIFIED version of the scanned maps.
---Cleavy McKnight
Department of Geology
Baylor University
cleavy2@earthlogic.baylor.edu