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                    Floodplain Analysis Toolkit
               Mother Earth Systems, Boulder, Colorado


This software was been developed for the U.S. Army Corps of Engineers,
Ft. Worth District under contract #DACW63-91-M-1085 and for the Omaha District
under contract #DACW45-92-P-1301.

This code is in the public domain.  Permission to use, copy, modify, and
distribute this software and its documentation for any purpose and without
fee is granted.

Mother Earth Systems disclaims all warranties with regard to this software,
including all implied warranties of merchantability and fitness. In no event
shall Mother Earth Systems be liable for any special, indirect or consequential
damages or any damages whatsoever resulting from loss of use, data or profits,
whether in an action of contract, negligence or other tortious action,
arising out of or in connection with the use or performance of this software.

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                         r.surf.voronoi

CREDITS:
Mother Earth Systems owes much credit to the following...

C.M. Gold (1989) "Surface interpolation, spatial adjacency and GIS" in
     _Three Dimensional Applications in Geographic Information Systems_
     Edited by Jonathan Raper; Taylor & Francis.
     (Gold's paper forms the basis for the r.surf.voronoi algorithm.)

Steve J. Fortune (1987) "A Sweepline Algorithm for Voronoi Diagrams"
     _Algorithmica_ 2, 153-174.
     (An implementation of Fortune's sweep algorithm, available via Internet, 
      lies at the heart of the r.surf.voronoi code ).

James Darrell McCauley (mccauley@ecn.purdue.edu) 
     (McCauley first integrated Fortune's sweep algorithm with GRASS to
      produce "s.voronoi".  McCauley's implementation provided a valuable
      example of the use of the sweep code for GRASS. )


LIMITATIONS:
1)  The sweep line code limits the number of voronoi sites to 4K.  
    This means that the number of non-zero cells in the GRASS input map 
    is also limited to 4K.

2)  r.surf.voronoi does not handle longitude/latitude data.

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AUTHOR INFORMATION:
Questions and suggestions are welcome. Write or call:

Terri L. Betancourt
Mother Earth Systems
891 Crescent Dr.
Boulder, CO 80303-2759
(303) 499-7883
