[GRASSLIST:5050] Re: difficulties with i.ortho.photo

[Richard Greenwood]

>When i register a camera, what is this "point of symmetry" that i have to 
>locate on the photo ?

It is something that is determined in the camera calibration. The 
photogrammetrist should be able to give you a calibration report for the 
camera, but if you don't know, assume 0,0. It's the center of the image.

>What is the origin and direction of X and Y on the photo ?

The origin is the center of the image (or the point of symetry) and X and Y 
are left-right and up-down.

My fiducial marks look something like this:
   X      Y
106  -106  lower right corner
-106 -106  lower left corner
-106  106  upper left corner
106   106  upper right corner
  0      112  bottom middle
-112    0   left middle
   0     112 top middle
112     0   right middle

Rich

Richard W. Greenwood, PLS
(307) 733-0203
Rich at GreenwoodMap.com
www.GreenwoodMap.com