Support for landscape index calculations on raster

DESCRIPTION

       This  documentation  is  focused on scientists and developers who wants to implement a new
       landscape index computation. Refer to the r.li modules overview and g.gui.rlisetup  module
       for user-focused documentation.

       r.li.daemon provides support for landscape index calculations on raster maps. It hides the
       management of areas,  defined  using  g.gui.rlisetup  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.  This function type  is  defined
       using typedef named rli_func.

       2      Create a main for command line arguments parsing, and call the function
                      int calculateIndex(char *file, rli_func *f,
                                         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 g.gui.rlisetup

           •   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.

       Refer  to  the  r.li  library  documentation in the source code and implementation of r.li
       modules for details and examples.

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
       g.gui.rlisetup

REFERENCES

       McGarigal, K., and B. J. Marks. 1995. FRAGSTATS:  spatial  pattern  analysis  program  for
       quantifying landscape structure. USDA For. Serv.  Gen. Tech. Rep. PNW-351. (PDF)

AUTHORS

       Claudio  Porta  and  Lucio  Davide  Spano, students of Computer Science University of Pisa
       (Italy).
       Commission from Faunalia Pontedera (PI)
       Rewritten from "r.le.setup" by William L. Baker
       Various bug fixes by Markus Metz
       This program is free software under the GPL (>=v2) Read the COPYING file that  comes  with
       GRASS for details.

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