Advice wanted: rectifying of aerial photographs

[Schmidt]

>Dear all,
>
>I need some expert advice on the (im)possibilities of rectifying
>aerial photographs with GRASS or other software. The problem: I
>received a set of hand-drawn maps that are based on a photo-interpretation
>of an area of approx. 10x15 km. The maps have been combined, by sticking
>colour copies together, to a map that is roughly on 1:20,000. However, the set
>of photos on which this map is based consists of two runs that are not
>exactly on the same scale. Needless to say that the number of reference
>points that I can find on the photographs is rather limited, and that
>the area is far from flat. The author of the map wants me to have it
>digitized and rectified in the UTM system.
>
>Is there any chance of doing this with a reasonable accuracy (e.g.
>with i.rectify), and if so, what are the conditions that should be 
>met? Any advice will be greatly appreciated!
>
>Philip Verhagen
>

You might want to look at i.ortho.photo in the alpha section of GRASS. It
seems to do a reasonable job of terrain correction with standard aerial
photography and an elevation map of the area.

Jim Schmidt
avenues at sonnet.com