[GRASS-user] align large number of images in a automated way

[Blumentrath, Stefan]

Hei again,

now I have digged a bit in this
http://grasswiki.osgeo.org/wiki/Orthorectification_digital_camera
and this
http://www.grassbook.org/neteler/papers/neteler2005_IJG_051-061_draft.pdf
and this:
http://www.grassbook.org/sample2nd/grassbook_2nd_2004_chapter10_aerial.pdf

Unfortunately I am still struggeling with understanding the calculation of the fiducial marks for the handheld camera (and the principal point of symmetry):
Is not the number of pixels for a know distance on the ground heavily affected by the camera perspective and the distance of the object to the camera, esp if the picture is not really taken in a birds-eye perspective (e.g. from a tower)? And does not the same problem arise for the principal point of symmetry (e.g. in a photo taken more parallel to the ground)?

Sorry for the probably fundamental questions, but all this is new for me...

Would it be a solution to take the average of distance in pixels and meters between the set of GCPs?
Esp. because my pictures only contain mountainous vegetation and rocks (no bridges, houses, roads and so on) it will be already a challenge to get good GCPs...

I could provide an example image if that helps understanding my problem...

Best,
Stefan