GRASS GIS 8 Programmer's Manual  8.2.2dev(2023)-e6660eef60
findzc.c File Reference

Zero Crossing functions. More...

#include <stdio.h>
#include <math.h>
Include dependency graph for findzc.c:

Go to the source code of this file.


#define TINY   1.0e-3


int G_math_findzc (double conv[], int size, double zc[], double thresh, int num_orients)
 Finds locations and orientations of zero crossings. More...

Detailed Description

Zero Crossing functions.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

GRASS GIS Development Team
Brad Douglas - rez at touchofmadness com

Definition in file findzc.c.

Macro Definition Documentation


#define TINY   1.0e-3

Definition at line 32 of file findzc.c.

Function Documentation

◆ G_math_findzc()

int G_math_findzc ( double  conv[],
int  size,
double  zc[],
double  thresh,
int  num_orients 

Finds locations and orientations of zero crossings.

Finds the locations and orientations of zero crossings in the input array conv, which is the result of the convolution of the Marr-Hildreth operator with the image. The output array is zc, which is non-zero only at zero crossing pixels. At those pixels, the value is 1 + (orientation), where orientation is a value from 0 to num_orients.

[in]sizesize of largest matrix column or row
[in]threshmagnitude threshold
int always returns 0

Definition at line 56 of file findzc.c.

References M_PI, M_PI_2, and TINY.