/*
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BSD 3-Clause License
Copyright (C) 2014, Olexa Bilaniuk, Hamid Bazargani & Robert Laganiere, all rights reserved.
Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:
* Redistribution's of source code must retain the above copyright notice,
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* The name of the copyright holders may not be used to endorse or promote products
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*/
/**
* Bilaniuk, Olexa, Hamid Bazargani, and Robert Laganiere. "Fast Target
* Recognition on Mobile Devices: Revisiting Gaussian Elimination for the
* Estimation of Planar Homographies." In Computer Vision and Pattern
* Recognition Workshops (CVPRW), 2014 IEEE Conference on, pp. 119-125.
* IEEE, 2014.
*/
/* Include Guards */
#ifndef __OPENCV_RHO_H__
#define __OPENCV_RHO_H__
/* Includes */
#include <opencv2/core.hpp>
#include <stdint.h>
/* Defines */
/* Flags */
#ifndef RHO_FLAG_NONE
#define RHO_FLAG_NONE (0U<<0)
#endif
#ifndef RHO_FLAG_ENABLE_NR
#define RHO_FLAG_ENABLE_NR (1U<<0)
#endif
#ifndef RHO_FLAG_ENABLE_REFINEMENT
#define RHO_FLAG_ENABLE_REFINEMENT (1U<<1)
#endif
#ifndef RHO_FLAG_ENABLE_FINAL_REFINEMENT
#define RHO_FLAG_ENABLE_FINAL_REFINEMENT (1U<<2)
#endif
/* Namespace cv */
namespace cv{
/* Data structures */
/**
* Homography Estimation context.
*/
struct RHO_HEST;
typedef struct RHO_HEST RHO_HEST;
/* Functions */
/**
* Initialize the estimator context, by allocating the aligned buffers
* internally needed.
*
* @return A pointer to the context if successful; NULL if an error occured.
*/
Ptr<RHO_HEST> rhoInit(void);
/**
* Ensure that the estimator context's internal table for non-randomness
* criterion is at least of the given size, and uses the given beta. The table
* should be larger than the maximum number of matches fed into the estimator.
*
* A value of N of 0 requests deallocation of the table.
*
* @param [in] p The initialized estimator context
* @param [in] N If 0, deallocate internal table. If > 0, ensure that the
* internal table is of at least this size, reallocating if
* necessary.
* @param [in] beta The beta-factor to use within the table.
* @return 0 if unsuccessful; non-zero otherwise.
*/
int rhoEnsureCapacity(Ptr<RHO_HEST> p, unsigned N, double beta);
/**
* Seeds the internal PRNG with the given seed.
*
* Although it is not required to call this function, since context
* initialization seeds itself with entropy from rand(), this function allows
* reproducible results by using a specified seed.
*
* @param [in] p The estimator context whose PRNG is to be seeded.
* @param [in] seed The 64-bit integer seed.
*/
void rhoSeed(Ptr<RHO_HEST> p, uint64_t seed);
/**
* Estimates the homography using the given context, matches and parameters to
* PROSAC.
*
* The given context must have been initialized.
*
* The matches are provided as two arrays of N single-precision, floating-point
* (x,y) points. Points with corresponding offsets in the two arrays constitute
* a match. The homography estimation attempts to find the 3x3 matrix H which
* best maps the homogeneous-coordinate points in the source array to their
* corresponding homogeneous-coordinate points in the destination array.
*
* Note: At least 4 matches must be provided (N >= 4).
* Note: A point in either array takes up 2 floats. The first of two stores
* the x-coordinate and the second of the two stores the y-coordinate.
* Thus, the arrays resemble this in memory:
*
* src = [x0, y0, x1, y1, x2, y2, x3, y3, x4, y4, ...]
* Matches: | | | | |
* dst = [x0, y0, x1, y1, x2, y2, x3, y3, x4, y4, ...]
* Note: The matches are expected to be provided sorted by quality, or at
* least not be worse-than-random in ordering.
*
* A pointer to the base of an array of N bytes can be provided. It serves as
* an output mask to indicate whether the corresponding match is an inlier to
* the returned homography, if any. A zero indicates an outlier; A non-zero
* value indicates an inlier.
*
* The PROSAC estimator requires a few parameters of its own. These are:
*
* - The maximum distance that a source point projected onto the destination
* plane can be from its putative match and still be considered an
* inlier. Must be non-negative.
* A sane default is 3.0.
* - The maximum number of PROSAC iterations. This corresponds to the
* largest number of samples that will be drawn and tested.
* A sane default is 2000.
* - The RANSAC convergence parameter. This corresponds to the number of
* iterations after which PROSAC will start sampling like RANSAC.
* A sane default is 2000.
* - The confidence threshold. This corresponds to the probability of
* finding a correct solution. Must be bounded by [0, 1].
* A sane default is 0.995.
* - The minimum number of inliers acceptable. Only a solution with at
* least this many inliers will be returned. The minimum is 4.
* A sane default is 10% of N.
* - The beta-parameter for the non-randomness termination criterion.
* Ignored if non-randomness criterion disabled, otherwise must be
* bounded by (0, 1).
* A sane default is 0.35.
* - Optional flags to control the estimation. Available flags are:
* HEST_FLAG_NONE:
* No special processing.
* HEST_FLAG_ENABLE_NR:
* Enable non-randomness criterion. If set, the beta parameter
* must also be set.
* HEST_FLAG_ENABLE_REFINEMENT:
* Enable refinement of each new best model, as they are found.
* HEST_FLAG_ENABLE_FINAL_REFINEMENT:
* Enable one final refinement of the best model found before
* returning it.
*
* The PROSAC estimator optionally accepts an extrinsic initial guess of H.
*
* The PROSAC estimator outputs a final estimate of H provided it was able to
* find one with a minimum of supporting inliers. If it was not, it outputs
* the all-zero matrix.
*
* The extrinsic guess at and final estimate of H are both in the same form:
* A 3x3 single-precision floating-point matrix with step 3. Thus, it is a
* 9-element array of floats, with the elements as follows:
*
* [ H00, H01, H02,
* H10, H11, H12,
* H20, H21, 1.0 ]
*
* Notice that the homography is normalized to H22 = 1.0.
*
* The function returns the number of inliers if it was able to find a
* homography with at least the minimum required support, and 0 if it was not.
*
*
* @param [in/out] p The context to use for homography estimation. Must
* be already initialized. Cannot be NULL.
* @param [in] src The pointer to the source points of the matches.
* Must be aligned to 4 bytes. Cannot be NULL.
* @param [in] dst The pointer to the destination points of the matches.
* Must be aligned to 4 bytes. Cannot be NULL.
* @param [out] inl The pointer to the output mask of inlier matches.
* Must be aligned to 4 bytes. May be NULL.
* @param [in] N The number of matches. Minimum 4.
* @param [in] maxD The maximum distance. Minimum 0.
* @param [in] maxI The maximum number of PROSAC iterations.
* @param [in] rConvg The RANSAC convergence parameter.
* @param [in] cfd The required confidence in the solution.
* @param [in] minInl The minimum required number of inliers. Minimum 4.
* @param [in] beta The beta-parameter for the non-randomness criterion.
* @param [in] flags A union of flags to fine-tune the estimation.
* @param [in] guessH An extrinsic guess at the solution H, or NULL if
* none provided.
* @param [out] finalH The final estimation of H, or the zero matrix if
* the minimum number of inliers was not met.
* Cannot be NULL.
* @return The number of inliers if the minimum number of
* inliers for acceptance was reached; 0 otherwise.
*/
unsigned rhoHest(Ptr<RHO_HEST> p, /* Homography estimation context. */
const float* src, /* Source points */
const float* dst, /* Destination points */
char* inl, /* Inlier mask */
unsigned N, /* = src.length = dst.length = inl.length */
float maxD, /* 3.0 */
unsigned maxI, /* 2000 */
unsigned rConvg, /* 2000 */
double cfd, /* 0.995 */
unsigned minInl, /* 4 */
double beta, /* 0.35 */
unsigned flags, /* 0 */
const float* guessH, /* Extrinsic guess, NULL if none provided */
float* finalH); /* Final result. */
/* End Namespace cv */
}
#endif