#include <mrpt/otherlibs/do_opencv_includes.h>
Go to the source code of this file.
Classes | |
struct | ransac_data |
holds feature data relevant to ransac More... | |
Macros | |
#define | RANSAC_ERR_TOL 3 |
#define | RANSAC_INLIER_FRAC_EST 0.25 |
pessimistic estimate of fraction of inlers for RANSAC More... | |
#define | RANSAC_PROB_BAD_SUPP 0.10 |
estimate of the probability that a correspondence supports a bad model More... | |
#define | feat_ransac_data(feat) ( (struct ransac_data*) (feat)->feature_data ) |
Typedefs | |
typedef CvMat *(* | ransac_xform_fn) (CvPoint2D64f *pts, CvPoint2D64f *mpts, int n) |
Prototype for transformation functions passed to ransac_xform(). More... | |
typedef double(* | ransac_err_fn) (CvPoint2D64f pt, CvPoint2D64f mpt, CvMat *M) |
Prototype for error functions passed to ransac_xform(). More... | |
Functions | |
CvMat * | ransac_xform (struct feature *features, int n, int mtype, ransac_xform_fn xform_fn, int m, double p_badxform, ransac_err_fn err_fn, double err_tol, struct feature ***inliers, int *n_in) |
Calculates a best-fit image transform from image feature correspondences using RANSAC. More... | |
CvMat * | lsq_homog (CvPoint2D64f *pts, CvPoint2D64f *mpts, int n) |
Calculates a least-squares planar homography from point correspondeces. More... | |
double | homog_xfer_err (CvPoint2D64f pt, CvPoint2D64f mpt, CvMat *H) |
Calculates the transfer error between a point and its correspondence for a given homography, i.e. More... | |
CvPoint2D64f | persp_xform_pt (CvPoint2D64f pt, CvMat *T) |
Performs a perspective transformation on a single point. More... | |
#define feat_ransac_data | ( | feat | ) | ( (struct ransac_data*) (feat)->feature_data ) |
#define RANSAC_INLIER_FRAC_EST 0.25 |
#define RANSAC_PROB_BAD_SUPP 0.10 |
typedef double(* ransac_err_fn) (CvPoint2D64f pt, CvPoint2D64f mpt, CvMat *M) |
Prototype for error functions passed to ransac_xform().
For a given point, its correspondence, and a transform, functions of this type should compute a measure of error between the correspondence and the point after the point has been transformed by the transform.
pt | a point |
mpt | pt's correspondence |
T | a transform |
typedef CvMat*(* ransac_xform_fn) (CvPoint2D64f *pts, CvPoint2D64f *mpts, int n) |
Prototype for transformation functions passed to ransac_xform().
Functions of this type should compute a transformation matrix given a set of point correspondences.
pts | array of points |
mpts | array of corresponding points; each pts[i], i=0..n-1, corresponds to mpts[i] |
n | number of points in both pts and mpts |
double homog_xfer_err | ( | CvPoint2D64f | pt, |
CvPoint2D64f | mpt, | ||
CvMat * | H | ||
) |
Calculates the transfer error between a point and its correspondence for a given homography, i.e.
for a point , it's correspondence , and homography , computes . Intended for use as a ransac_err_fn.
pt | a point |
mpt | pt's correspondence |
H | a homography matrix |
CvMat* lsq_homog | ( | CvPoint2D64f * | pts, |
CvPoint2D64f * | mpts, | ||
int | n | ||
) |
Calculates a least-squares planar homography from point correspondeces.
Intended for use as a ransac_xform_fn.
pts | array of points |
mpts | array of corresponding points; each pts[i], i=0..n-1, corresponds to mpts[i] |
n | number of points in both pts and mpts; must be at least 4 |
CvPoint2D64f persp_xform_pt | ( | CvPoint2D64f | pt, |
CvMat * | T | ||
) |
Performs a perspective transformation on a single point.
That is, for a point and a matrix this function returns the point , where
,
and
.
Note that affine transforms are a subset of perspective transforms.
pt | a 2D point |
T | a perspective transformation matrix |
CvMat* ransac_xform | ( | struct feature * | features, |
int | n, | ||
int | mtype, | ||
ransac_xform_fn | xform_fn, | ||
int | m, | ||
double | p_badxform, | ||
ransac_err_fn | err_fn, | ||
double | err_tol, | ||
struct feature *** | inliers, | ||
int * | n_in | ||
) |
Calculates a best-fit image transform from image feature correspondences using RANSAC.
For more information refer to:
Fischler, M. A. and Bolles, R. C. Random sample consensus: a paradigm for model fitting with applications to image analysis and automated cartography. Communications of the ACM, 24, 6 (1981), pp. 381–395.
features | an array of features; only features with a non-NULL match of type mtype are used in homography computation |
n | number of features in feat |
mtype | determines which of each feature's match fields to use for transform computation; should be one of FEATURE_FWD_MATCH, FEATURE_BCK_MATCH, or FEATURE_MDL_MATCH; if this is FEATURE_MDL_MATCH, correspondences are assumed to be between a feature's img_pt field and its match's mdl_pt field, otherwise correspondences are assumed to be between the the feature's img_pt field and its match's img_pt field |
xform_fn | pointer to the function used to compute the desired transformation from feature correspondences |
m | minimum number of correspondences necessary to instantiate the transform computed by xform_fn |
p_badxform | desired probability that the final transformation returned by RANSAC is corrupted by outliers (i.e. the probability that no samples of all inliers were drawn) |
err_fn | pointer to the function used to compute a measure of error between putative correspondences for a given transform |
err_tol | correspondences within this distance of each other are considered as inliers for a given transform |
inliers | if not NULL, output as an array of pointers to the final set of inliers |
n_in | if not NULL, output as the final number of inliers |
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