core/vil/algo/vil_corners.cxx File Reference

Estimate corner positions using Forstner/Harris approach. More...

#include "vil_corners.h"
#include <vil/vil_fill.h>
#include <vcl_cassert.h>
#include <vil/algo/vil_gauss_filter.h>
#include <vil/vil_math.h>

Go to the source code of this file.

Functions
void	vil_corners (const vil_image_view< float > &grad_i, const vil_image_view< float > &grad_j, vil_image_view< float > &dest, double k)
	Compute Forstner/Harris corner strength function given gradient images.
void	vil_corners (const vil_image_view< double > &grad_i, const vil_image_view< double > &grad_j, vil_image_view< double > &dest, double k)
void	vil_corners_rohr (const vil_image_view< float > &gx, const vil_image_view< float > &gy, vil_image_view< float > &corner_im)
	Compute corner strength using Rohr's recommended method.

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Detailed Description

Estimate corner positions using Forstner/Harris approach.

Author:

Tim Cootes

Definition in file vil_corners.cxx.

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Function Documentation

void vil_corners	(	const vil_image_view< float > &	grad_i,
		const vil_image_view< float > &	grad_j,
		vil_image_view< float > &	dest,
		double	k
	)

Compute Forstner/Harris corner strength function given gradient images.

Compute Harris corner strength function given gradient images.

grad_i and grad_j are assumed to be the i and j gradient images (single plane), such as produced by vil_sobel_3x3(). At each pixel compute the Forstner/Harris corner function: det(H)-k*sqr(trace(H)), where H is the 2x2 matrix of second derivatives, generated by applying a Sobel operator to the gradient images.

The local peaks of the output image correspond to corner candidates.

grad_i and grad_j are assumed to be the i and j gradient images (single plane), such as produced by vil_sobel_3x3(). At each pixel compute the Harris corner function: det(H)-k*sqr(trace(H)), where H is the 2x2 matrix of second derivatives, generated by applying a Sobel operator to the gradient images.

The local peaks of the output image correspond to corner candidates.

Definition at line 21 of file vil_corners.cxx.

void vil_corners	(	const vil_image_view< double > &	grad_i,
		const vil_image_view< double > &	grad_j,
		vil_image_view< double > &	dest,
		double	k
	)

Definition at line 98 of file vil_corners.cxx.

void vil_corners_rohr	(	const vil_image_view< float > &	gx,
		const vil_image_view< float > &	gy,
		vil_image_view< float > &	corner_im
	)

Compute corner strength using Rohr's recommended method.

This computes the determinant of the matrix C=g.g' after the elements of C have been smoothed. g is the vector of first derivatives (gx,gy)' It relies only on first derivatives.

Currently uses somewhat inefficient multi-pass method. Could be improved.

This computes the determinant of the matrix C=g.g' after the elements of C have been smoothed. g is the vector of first derivatives (gx,gy)' It relies only on first derivatives.

Definition at line 183 of file vil_corners.cxx.