fundamental_matrix.h

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// ----------------------------------------------------------------------------
// -                        CloudViewer: www.cloudViewer.org                  -
// ----------------------------------------------------------------------------
// Copyright (c) 2018-2024 www.cloudViewer.org
// SPDX-License-Identifier: MIT
// ----------------------------------------------------------------------------
 
#pragma once
 
#include <Eigen/Core>
#include <vector>
 
#include "estimators/homography_matrix.h"
#include "util/alignment.h"
#include "util/types.h"
 
namespace colmap {
 
// Fundamental matrix estimator from corresponding point pairs.
//
// This algorithm solves the 7-Point problem and is based on the following
// paper:
//
//    Zhengyou Zhang and T. Kanade, Determining the Epipolar Geometry and its
//    Uncertainty: A Review, International Journal of Computer Vision, 1998.
//    http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.33.4540
class FundamentalMatrixSevenPointEstimator {
public:
    typedef Eigen::Vector2d X_t;
    typedef Eigen::Vector2d Y_t;
    typedef Eigen::Matrix3d M_t;
 
    // The minimum number of samples needed to estimate a model.
    static const int kMinNumSamples = 7;
 
    // Estimate either 1 or 3 possible fundamental matrix solutions from a set
    // of corresponding points.
    //
    // The number of corresponding points must be exactly 7.
    //
    // @param points1  First set of corresponding points.
    // @param points2  Second set of corresponding points
    //
    // @return         Up to 4 solutions as a vector of 3x3 fundamental
    // matrices.
    static std::vector<M_t> Estimate(const std::vector<X_t>& points1,
                                     const std::vector<Y_t>& points2);
 
    // Calculate the residuals of a set of corresponding points and a given
    // fundamental matrix.
    //
    // Residuals are defined as the squared Sampson error.
    //
    // @param points1    First set of corresponding points as Nx2 matrix.
    // @param points2    Second set of corresponding points as Nx2 matrix.
    // @param F          3x3 fundamental matrix.
    // @param residuals  Output vector of residuals.
    static void Residuals(const std::vector<X_t>& points1,
                          const std::vector<Y_t>& points2,
                          const M_t& F,
                          std::vector<double>* residuals);
};
 
// Fundamental matrix estimator from corresponding point pairs.
//
// This algorithm solves the 8-Point problem based on the following paper:
//
//    Hartley and Zisserman, Multiple View Geometry, algorithm 11.1, page 282.
class FundamentalMatrixEightPointEstimator {
public:
    typedef Eigen::Vector2d X_t;
    typedef Eigen::Vector2d Y_t;
    typedef Eigen::Matrix3d M_t;
 
    // The minimum number of samples needed to estimate a model.
    static const int kMinNumSamples = 8;
 
    // Estimate fundamental matrix solutions from a set of corresponding points.
    //
    // The number of corresponding points must be at least 8.
    //
    // @param points1  First set of corresponding points.
    // @param points2  Second set of corresponding points
    //
    // @return         Single solution as a vector of 3x3 fundamental matrices.
    static std::vector<M_t> Estimate(const std::vector<X_t>& points1,
                                     const std::vector<Y_t>& points2);
 
    // Calculate the residuals of a set of corresponding points and a given
    // fundamental matrix.
    //
    // Residuals are defined as the squared Sampson error.
    //
    // @param points1    First set of corresponding points as Nx2 matrix.
    // @param points2    Second set of corresponding points as Nx2 matrix.
    // @param F          3x3 fundamental matrix.
    // @param residuals  Output vector of residuals.
    static void Residuals(const std::vector<X_t>& points1,
                          const std::vector<Y_t>& points2,
                          const M_t& F,
                          std::vector<double>* residuals);
};
 
}  // namespace colmap