r.li.daemon(1grass) GRASS GIS User's Manual r.li.daemon(1grass)
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 func-
tion 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.patch-
density.
Refer to the r.li library documentation in the source code and imple-
mentation 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 sys-
tem. 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 analy-
sis 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 Uni-
versity 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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GRASS 7.8.7 r.li.daemon(1grass)
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