NAME

       libgrass_rli - r.li landscape index support library

DESCRIPTION

       r.li.daemon provides support for landscape index calculations on raster maps. It hides the
       management of areas, defined using r.li.setup command. It is not used  like  a  standalone
       program, but its functions are a library used by all r.li.[index] commands.
       This description is a tutorial for new index definition.
       The  developer  has  only to focus on a unique area, like in mathematical definitions, and
       has to write a C implementation of it.
       The areas are defined using a struct called area_des and it members are explained  in  the
       source code (doxygen) documentation.

       To write a new index only two steps are needed:

       1      Define a function and insert its declaration on file index.h in r.li.daemon folder,
              which contains all index declarations. This function must be of this kind:
                      int index(int fd, char ** par, area_des ad, double * result)

              where:

                     fd is the raster map descriptor

                     par is a matrix for special parameter (like argv in main)

                     ad is the area descriptor

                     result is where to put the index calculation result
       This function has to return 1 on success and 0 otherwise.

       6      Create a main for command line arguments parsing, and call the function
                      int calculateIndex(char * file, int f(int, char** area_des, double *), char
              **parameters, char *raster, char *output);

              from the r.li library, for starting raster analysis.
              It follows the meaning of parameters:

                     file name of configuration file created using r.li.setup

                     f pointer to index function defined above

                     parameters pointer to index special parameters

                     raster name of raster to use

                     output output file name

       Compile it using a changed Makefile based on the file for r.li.patchdensity.

NOTES

       Using GRASS library function to access raster rows can slow down moving windows execution.
       It is recommended to use
       RLI_get_cell_row(int, int, area_des)
       RLI_get_fcell_row(int, int, area_des)
       RLI_get_dcell_row(int, int, area_des)

       to use an ad  hoc  build  memory  management  developed  to  speed  up  the  system.   The
       documentation is in doxygen files.

SEE ALSO

       old r.le manual
       r.li package overview
       r.li.patchdensity, r.li.setup

AUTHORS

       Claudio  Porta  and  Lucio  Davide  Spano, students of Computer Science University of Pisa
       (Italy).
       Commission from Faunalia Pontedera (PI)
       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.

       Last changed: $Date: 2013-06-16 05:08:46 +0200 (Sun, 16 Jun 2013) $

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