Perl Module Geo::RasterAlgebra - 0.20

     Copyright (c) 1999-2004 Ari Jolma. All rights reserved.
     This program is free software; you can redistribute it and/or
     modify it under the same terms as Perl itself. That is, using
     either

	a) the GNU General Public License as published by the Free
	Software Foundation; or

	b) the "Artistic License".

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See either
    the GNU General Public License or the Artistic License for more details.

    You should have received a copy of the Artistic License with this
    Kit, in the file named "Artistic".  If not, get it from
    http://www.perl.com/language/misc/Artistic.html.

    You should also have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software Foundation,
    Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.

ACKNOWLEDGEMENTS

array.c and array.h are taken from the Karl Glazebrook's PGPLOT
distribution.

function gdline in grid.c is taken from Thomas Boutell's gd library.

excerpts from the pgplot.doc are Copyright (c) 1983-1997 by the
California Institute of Technology.

INSTALLATION

To install, unzip and untar the archive. In the directory created type

perl Makefile.pl
make
make test
make install

Geo::RasterAlgebra requires the Raster Algebra Library libral. libral
is at <http://sourceforge.net/projects/libral>.

Required modules are ExtUtils::Depends and ExtUtils:F77 if PGPLOT is
found.

Documentation is in the module file and will be added onto
perllocal.pod as usual.

DESCRIPTION

Geo::RasterAlgebra has three purposes/goals:

1. To be a general purpose Perl/C tool for large 2-dimensional
   grids or matrixes of integer and/or real numbers. Large
   means too large/slow to handle in just Perl.

2. To be a general purpose Perl/C tool for doing raster GIS
   (Geographic Information System) work. This means "raster/map
   algebra" (overlaying and masking DEMs (Digital Elevation Models),
   land-use rasters, etc), spatial analyses (kriging, ...), 
   extracting indices from the grids (histograms, ...), interactive
   display, etc.

3. To be a general purpose Perl/C tool for doing hydrologic and
   water resources GIS work. This means watershed delineation,
   finding stream networks, calculating indices (topographic
   index, ...), preparing data for hydrologic models,
   developing spatially distributed hydrologic modeling, etc.

I'm interested in the section 3. but I could not find good support for
sections 1. and 2 (in the sense of playing with number 3). so I
included them into this project.

The small script rash.pl uses Term::ReadLine and is used to implement
a simple but very useful environment for "doing raster algebra GIS
with Perl". The rash.pl can have a live connection to gnuplot and
Postgres (if invoked with option -a), this is on a basic level now,
for example histograms are simple to plot and rgb values for a grid
can be retrieved from a database.

NOTES

The library uses non-portable(?) binary format to store the grids.
The default format is hdr/bil.

THE DEMO

The demo, which is a part of the test suite, is a demonstration of
basin delineation and derivation of stream network and
subcatchments. The data which is used is real but the world
coordinates and name are hidden not to reveal the true identity of the
place.

OTHER SOFTWARE

Other software with more or less similar aims but not related to
Grid.pm:

PCRaster http://www.geog.uu.nl/pcraster.html
RiverTools http://cires.colorado.edu/people/peckham.scott/RT.html
TAPES http://cres.anu.edu.au/software/tapes.html
TARDEM http://www.engineering.usu.edu/dtarb/tardem.html
TOPOG http://www.clw.csiro.au/topog/user/user.html
TOPAZ http://grl.ars.usda.gov/topaz/TOPAZ1.HTM

and of course

GRASS http://www.baylor.edu/~grass/
ARC/INFO http://www.esri.com/software/arcinfo/index.html