[GRASSLIST:2937] Photo.camera reference file

[Kirk Schmidt]

The command photo.camera is used to set up a camera reference file that 
provides the camera
details prior to using orthorectifying an image.

The format allows the user to set up the fiducial mark coordinates but I 
am not certain of the units and what they are oriented against?
Could they be in mm and their distance from the image center (Principle 
Point)?

Thanks

Kirk Schmidt