STATUS:
	The i.ortho.photo suite of modules has been temporarily disabled 
	from GRASS 7 as they are heavily dependent on the text-based
	Vask library and interactive XDRIVER monitors, both of which
	have been removed. As the modules are rewritten to run in non-
	interactive mode or with a wxPython frontend, they will be
	added back into GRASS 7. This work has been undertaken in the
	to some extent in the development branch.

AUTHORS:
	The orthophoto rectification programs went out under alpha in 4.0.
	It has since had bug fixes performed by OGI (Shapiro?) and also by
	the original programmer - Mike Baba of DBA Systems, Fairfax, VA.

COPYRIGHT:    (C) 1999-2019 by the GRASS Development Team

               This program is free software under the GNU General Public
               License (>=v2). Read the file COPYING that comes with GRASS
               for details.


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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)

GRASS GIS 7

     G6                  G7
frontend:
 i.ortho.photo  -> i.ortho.rectify + TODO wxGUI

internal:
 libes/         -> lib/
 menu/          -> TODO (wxGUI, use g.gui.gcp classes)
 photo.elev/    -> i.ortho.elev/
 photo.2target/ -> ? i.ortho.transform/ 
 photo.camera/  -> i.ortho.camera/
 photo.2image/  -> ? (wxGUI, use g.gui.gcp classes: fiducial marks)
 photo.init/    -> i.ortho.init/
 photo.rectify/ -> ? i.ortho.rectify/


Workflow description:

Open Source GIS: A GRASS GIS Approach, Second Edition, 2004
by Markus Neteler and Helena Mitasova, 
Chapter 10 – PROCESSING OF AERIAL PHOTOS
http://grassbook.org/extra/sample-chapter/
--> PDF

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GRASS GIS 4 to 6

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 GRASS 6 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 parameters

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