sample.c File Reference

Raster library - Sampling methods (extract a cell value from raster map) More...

#include <string.h>
#include <unistd.h>
#include <math.h>
#include <grass/gis.h>
#include <grass/raster.h>
#include <grass/glocale.h>

Include dependency graph for sample.c:

Go to the source code of this file.

Functions
DCELL	Rast_get_sample (int fd, const struct Cell_head *window, struct Categories *cats, double north, double east, int usedesc, INTERP_TYPE itype)
	Extract a cell value from raster map. More...
DCELL	Rast_get_sample_nearest (int fd, const struct Cell_head *window, struct Categories *cats, double north, double east, int usedesc)
	Extract a cell value from raster map (neighbor interpolation) More...
DCELL	Rast_get_sample_bilinear (int fd, const struct Cell_head *window, struct Categories *cats, double north, double east, int usedesc)
	Extract a cell value from raster map (bilinear interpolation). More...
DCELL	Rast_get_sample_cubic (int fd, const struct Cell_head *window, struct Categories *cats, double north, double east, int usedesc)
	Extract a cell value from raster map (cubic interpolation). More...

Detailed Description

Raster library - Sampling methods (extract a cell value from raster map)

1/2006: moved to libgis from v.sample/v.drape for clone removal

(C) 2001-2009 by the GRASS Development Team

This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.

Author

James Darrell McCauley <darrell mccauley-usa.com>, http://mccauley-usa.com/

Definition in file sample.c.

Function Documentation

Rast_get_sample()

DCELL Rast_get_sample	(	int	fd,
		const struct Cell_head *	window,
		struct Categories *	cats,
		double	north,
		double	east,
		int	usedesc,
		INTERP_TYPE	itype
	)

Extract a cell value from raster map.

Extract a cell value from raster map at given northing and easting with a sampled 3x3 window using a specified interpolation method.

• NEAREST neighbor interpolation
• BILINEAR bilinear interpolation
• CUBIC cubic interpolation

Parameters

fd	file descriptor
window	region settings
cats	categories
north	northing position
east	easting position
usedesc	flag to scan category label
itype	interpolation method

Returns

cell value at given position

Definition at line 48 of file sample.c.

Rast_get_sample_bilinear()

DCELL Rast_get_sample_bilinear	(	int	fd,
		const struct Cell_head *	window,
		struct Categories *	cats,
		double	north,
		double	east,
		int	usedesc
	)

Extract a cell value from raster map (bilinear interpolation).

Extract a cell value from raster map at given northing and easting with a sampled 3x3 window using a bilinear interpolation.

Parameters

fd	file descriptor
window	region settings
cats	categories
north	northing position
east	easting position
usedesc	flag to scan category label

Returns

cell value at given position

Definition at line 148 of file sample.c.

Rast_get_sample_cubic()

DCELL Rast_get_sample_cubic	(	int	fd,
		const struct Cell_head *	window,
		struct Categories *	cats,
		double	north,
		double	east,
		int	usedesc
	)

Extract a cell value from raster map (cubic interpolation).

Extract a cell value from raster map at given northing and easting with a sampled 3x3 window using a cubic interpolation.

Parameters

fd	file descriptor
window	region settings
cats	categories
north	northing position
east	easting position
usedesc	flag to scan category label

Returns

cell value at given position

Definition at line 238 of file sample.c.

Rast_get_sample_nearest()

DCELL Rast_get_sample_nearest	(	int	fd,
		const struct Cell_head *	window,
		struct Categories *	cats,
		double	north,
		double	east,
		int	usedesc
	)

Extract a cell value from raster map (neighbor interpolation)

Extract a cell value from raster map at given northing and easting with a sampled 3x3 window using a neighbor interpolation.

Parameters

fd	file descriptor
window	region settings
cats	categories
north	northing position
east	easting position
usedesc	flag to scan category label

Returns

cell value at given position

Definition at line 91 of file sample.c.