Main algorithm reference (basically libes/orthoref.c):

Elements of Photogrammetry, With Air Photo Interpretation and Remote Sensing
by Paul R. Wolf, 562 pages
Publisher: McGraw Hill Text; 2nd edition (January 1983)


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The main program is i.ortho.photo which is just a menu driver for the 
following programs:

1 i.group
2 photo.target
3 photo.init
4 photo.camera
5 photo.elev
6 photo.2image
7 photo.2target
8 photo.rectify



The following directories contain the source code:

	./menu:			main menu code       (-> menu/menu.c)

	./photo.target:		select target location and mapset

	./photo.elev:		select elevation model
 
	./photo.camera:		select a camera to use for parameters

	./photo.2image:		code for image to photo coordinate
				transformation

	./photo.init:		choose initial camera exposure station
				parameters

	./photo.2target:	computes photo to target location
				transformation paramters

	./photo.rectify:	does the actual image rectification
	
	./libes:		libraries for ortho programs
