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Geografic-Information-System


			
				
					
						
						
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<h2>NAME</h2>
<em><b>libgrass_rli</b></em> - r.li landscape index support library

<h2>DESCRIPTION</h2>

<em>r.li.daemon</em> provides support for landscape index calculations on raster
maps. It hides the managment of areas, defined using <a href="r.li.setup.html">r.li.setup</a>
command. It is not used like a standalone program, but its functions are 
a library used by all <em>r.li.[index]</em> commands.<br>
This description is a tutorial for new index definition. <br><br>
The developer has only to focus on a unique area, like in mathematical definitions, and
has to write a C implementation of it.<br>
The areas are defined using a <em>struct</em> called <b>area_des</b> and it members are
explained in the source code (doxygen) documentation.
<p>
To write a new index only two steps are needed: 
<ol>
	<li>
	Define a function and insert its declaration on file <b>index.h</b> in <em>r.li.daemon</em>
	folder, which contains all index declarations. This function must be of this kind:
	<br><div class="code"><pre>
        int index(int fd, char ** par, area_des ad, double * result)
	</pre></div><br>
	where: <ul>
			<li><i>fd</i> is the raster map descriptor
			<li><i>par</i> is a matrix for special parameter (like argv in main)
			<li><i>ad</i> is the area descriptor 
			<li><i>result</i> is where to put the index calculation result
		</ul>
	This function has to return 1 on success and 0 otherwise. <br><br>
	<li>
	Create a main for command line arguments parsing, and call the function
	<br><div class="code"><pre>
        int calculateIndex(char * file, int f(int, char** area_des, double *), char **parameters, char *raster, char *output);
	</pre></div><br>
	from the <i>r.li</i> library, for starting raster analysis.<br>
	It follows the meaning of parameters:
	<ul>
	<li><i>file</i> name of configuration file created using <a href="r.li.setup.html">r.li.setup</a>
	<li><i>f</i> pointer to index function defined above
	<li><i>parameters</i> pointer to index special parameters
	<li><i>raster</i> name of raster to use
	<li><i>output</i> output file name
	</ul>
</ol>
Compile it using a changed Makefile based on the file for <em>r.li.patchdensity</em>.

<h2>NOTES</h2>
Using GRASS library function to access raster rows can slow down moving windows 
execution. It is recommended to use 
<br><div class="code"><pre>
RLI_get_cell_row(int, int, area_des)
RLI_get_fcell_row(int, int, area_des)
RLI_get_dcell_row(int, int, area_des)
</pre></div><br>
to use an ad hoc build memory managment developed to speed up the system.
The documentation is in doxygen files.

<h2>SEE ALSO</h2>

<em><a href="http://grass.osgeo.org/gdp/landscape/r_le_manual5.pdf">old r.le manual</A></em><br>
<em><a href="r.li.html">r.li</A></em> package overview <br>
<em><a href="r.li.patchdensity.html">r.li.patchdensity</A></em>,
<em><a href="r.li.setup.html">r.li.setup</A></em>

<h2>AUTHORS</h2>
Claudio Porta and Lucio Davide Spano, students of Computer Science 
University of Pisa (Italy).<br>
Commission from Faunalia Pontedera (PI)<br>
Rebuild of r.le.setup from William L. Baker
This program is free software under the GPL (>=v2)
Read the COPYING file that comes with GRASS for details.

<p>
<i>Last changed: $Date$</i>

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