This directory contains Tsai's Camera Calibration Software (C code), 
which uses the minpack routines (also here).

Also there is a class 'TsaiCal' which contains methods to convert
from world to image coordinates. The constructor needs Camera Parameters in
the format obtained from Tsai's Calibration C software.                   
This class allows the use of several calibrated cameras within a single  
application, although Tsai's Calibration C software will need to be used in
advance to work out the Camera Parameters from calibration data of        
correspondences between points. (either coplanar calibration or non-coplanar)
                                                                            
Chris Needham - Leeds Vision Group, School of Computing. 28-Nov-2001 

Useful routines are 'ccal_fo'
Which calibrates a camera given a set of many 7 < x < 500 correspondences
of the form  Xw Yw Zw u v 
with Zw = 0 if coplanar data used. All world obs in [mm], image u,v in pixels.

This creates a file of 12 Camera Parameters used by TsaiCal.

Thus once calibrated offline, several calibrated cameras can be used to
project points from image to world and world to image in a tracking 
application or the like, using the TsaiCal class.

See wc2ic.cpp for a C++ style wc2ic.c program.

enjoy,
  Chris.