#include <mrpt/otherlibs/do_opencv_includes.h>

Classes
struct	detection_data
	holds feature data relevant to detection More...

Macros
#define	SIFT_INTVLS 3
	default number of sampled intervals per octave More...

#define	SIFT_SIGMA 1.6
	default sigma for initial gaussian smoothing More...

#define	SIFT_IMG_DBL 1
	default threshold on keypoint contrast \|D(x)\| More...

#define	SIFT_DESCR_WIDTH 4
	default width of descriptor histogram array More...

#define	SIFT_DESCR_HIST_BINS 8
	default number of bins per histogram in descriptor array More...

#define	SIFT_INIT_SIGMA 0.5

#define	SIFT_IMG_BORDER 5

#define	SIFT_MAX_INTERP_STEPS 5

#define	SIFT_ORI_HIST_BINS 36

#define	SIFT_ORI_SIG_FCTR 1.5

#define	SIFT_ORI_RADIUS 3.0 * SIFT_ORI_SIG_FCTR

#define	SIFT_ORI_SMOOTH_PASSES 2

#define	SIFT_ORI_PEAK_RATIO 0.8

#define	SIFT_DESCR_SCL_FCTR 3.0

#define	SIFT_DESCR_MAG_THR 0.2

#define	SIFT_INT_DESCR_FCTR 512.0

#define	feat_detection_data(f) ((struct detection_data*)(f->feature_data))

Functions
int	sift_features (IplImage img, struct feature *feat)
	Finds SIFT features in an image using default parameter values. More...

int	_sift_features (IplImage img, struct feature *feat, int intvls, double sigma, double contr_thr, int curv_thr, int img_dbl, int descr_width, int descr_hist_bins)
	Finda SIFT features in an image using user-specified parameter values. More...

Macro Definition Documentation

◆ feat_detection_data

#define feat_detection_data ( f ) ((struct detection_data*)(f->feature_data))

Definition at line 93 of file sift.h.

Referenced by mrpt::vision::CFeatureExtraction::my_scale_space_extrema().

◆ SIFT_DESCR_HIST_BINS

#define SIFT_DESCR_HIST_BINS 8

default number of bins per histogram in descriptor array

Definition at line 57 of file sift.h.

Referenced by mrpt::vision::CFeatureExtraction::extractFeaturesSIFT(), and mrpt::vision::CFeatureExtraction::internal_computeSiftDescriptors().

◆ SIFT_DESCR_MAG_THR

#define SIFT_DESCR_MAG_THR 0.2

Definition at line 87 of file sift.h.

◆ SIFT_DESCR_SCL_FCTR

#define SIFT_DESCR_SCL_FCTR 3.0

Definition at line 84 of file sift.h.

◆ SIFT_DESCR_WIDTH

#define SIFT_DESCR_WIDTH 4

default width of descriptor histogram array

Definition at line 54 of file sift.h.

Referenced by mrpt::vision::CFeatureExtraction::extractFeaturesSIFT(), and mrpt::vision::CFeatureExtraction::internal_computeSiftDescriptors().

◆ SIFT_IMG_BORDER

#define SIFT_IMG_BORDER 5

Definition at line 63 of file sift.h.

◆ SIFT_IMG_DBL

#define SIFT_IMG_DBL 1

default threshold on keypoint contrast |D(x)|

default threshold on keypoint ratio of principle curvatures double image size before pyramid construction?

Definition at line 51 of file sift.h.

Referenced by mrpt::vision::CFeatureExtraction::extractFeaturesSIFT(), and mrpt::vision::CFeatureExtraction::internal_computeSiftDescriptors().

◆ SIFT_INIT_SIGMA

#define SIFT_INIT_SIGMA 0.5

Definition at line 60 of file sift.h.

◆ SIFT_INT_DESCR_FCTR

#define SIFT_INT_DESCR_FCTR 512.0

Definition at line 90 of file sift.h.

◆ SIFT_INTVLS

#define SIFT_INTVLS 3

default number of sampled intervals per octave

Definition at line 39 of file sift.h.

Referenced by mrpt::vision::CFeatureExtraction::extractFeaturesSIFT(), and mrpt::vision::CFeatureExtraction::internal_computeSiftDescriptors().

◆ SIFT_MAX_INTERP_STEPS

#define SIFT_MAX_INTERP_STEPS 5

Definition at line 66 of file sift.h.

◆ SIFT_ORI_HIST_BINS

#define SIFT_ORI_HIST_BINS 36

Definition at line 69 of file sift.h.

◆ SIFT_ORI_PEAK_RATIO

#define SIFT_ORI_PEAK_RATIO 0.8

Definition at line 81 of file sift.h.

◆ SIFT_ORI_RADIUS

#define SIFT_ORI_RADIUS 3.0 * SIFT_ORI_SIG_FCTR

Definition at line 75 of file sift.h.

◆ SIFT_ORI_SIG_FCTR

#define SIFT_ORI_SIG_FCTR 1.5

Definition at line 72 of file sift.h.

◆ SIFT_ORI_SMOOTH_PASSES

#define SIFT_ORI_SMOOTH_PASSES 2

Definition at line 78 of file sift.h.

◆ SIFT_SIGMA

#define SIFT_SIGMA 1.6

default sigma for initial gaussian smoothing

Definition at line 42 of file sift.h.

Referenced by mrpt::vision::CFeatureExtraction::extractFeaturesSIFT(), mrpt::vision::CFeatureExtraction::internal_computeSiftDescriptors(), and mrpt::vision::CFeatureExtraction::my_scale_space_extrema().

Function Documentation

◆ _sift_features()

int _sift_features	(	IplImage *	img,
		struct feature **	feat,
		int	intvls,
		double	sigma,
		double	contr_thr,
		int	curv_thr,
		int	img_dbl,
		int	descr_width,
		int	descr_hist_bins
	)

Finda SIFT features in an image using user-specified parameter values.

All detected features are stored in the array pointed to by feat.

Parameters

img	the image in which to detect features
feat	a pointer to an array in which to store detected features
intvls	the number of intervals sampled per octave of scale space
sigma	the amount of Gaussian smoothing applied to each image level before building the scale space representation for an octave
contr_thr	a threshold on the value of the scale space function $\left\|D(\hat{x})\right\|$ , where $\hat{x}$ is a vector specifying feature location and scale, used to reject unstable features; assumes pixel values in the range [0, 1]
curv_thr	threshold on a feature's ratio of principle curvatures used to reject features that are too edge-like
img_dbl	should be 1 if image doubling prior to scale space construction is desired or 0 if not
descr_width	the width, , of the $n \times n$ array of orientation histograms used to compute a feature's descriptor
descr_hist_bins	the number of orientations in each of the histograms in the array used to compute a feature's descriptor