utils.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 "util/alignment.h"
#include "util/types.h"
 
namespace colmap {
 
// Center and normalize image points.
//
// The points are transformed in a two-step procedure that is expressed
// as a transformation matrix. The matrix of the resulting points is usually
// better conditioned than the matrix of the original points.
//
// Center the image points, such that the new coordinate system has its
// origin at the centroid of the image points.
//
// Normalize the image points, such that the mean distance from the points
// to the coordinate system is sqrt(2).
//
// @param points          Image coordinates.
// @param normed_points   Transformed image coordinates.
// @param matrix          3x3 transformation matrix.
void CenterAndNormalizeImagePoints(const std::vector<Eigen::Vector2d>& points,
                                   std::vector<Eigen::Vector2d>* normed_points,
                                   Eigen::Matrix3d* matrix);
 
// Calculate the residuals of a set of corresponding points and a given
// fundamental or essential 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 E           3x3 fundamental or essential matrix.
// @param residuals   Output vector of residuals.
void ComputeSquaredSampsonError(const std::vector<Eigen::Vector2d>& points1,
                                const std::vector<Eigen::Vector2d>& points2,
                                const Eigen::Matrix3d& E,
                                std::vector<double>* residuals);
 
// Calculate the squared reprojection error given a set of 2D-3D point
// correspondences and a projection matrix. Returns DBL_MAX if a 3D point is
// behind the given camera.
//
// @param points2D      Normalized 2D image points.
// @param points3D      3D world points.
// @param proj_matrix   3x4 projection matrix.
// @param residuals     Output vector of residuals.
void ComputeSquaredReprojectionError(
        const std::vector<Eigen::Vector2d>& points2D,
        const std::vector<Eigen::Vector3d>& points3D,
        const Eigen::Matrix3x4d& proj_matrix,
        std::vector<double>* residuals);
 
}  // namespace colmap