Code tutorial

samples/cpp/tutorial_code/calib3d/real_time_pose_estimation/src/PnPProblem.cpp

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+/*
+ * PnPProblem.cpp
+ *
+ *  Created on: Mar 28, 2014
+ *      Author: Edgar Riba
+ */
+
+#include <iostream>
+#include <sstream>
+
+#include "PnPProblem.h"
+#include "Mesh.h"
+
+#include <opencv2/calib3d/calib3d.hpp>
+
+
+/* Functions for Möller–Trumbore intersection algorithm
+ * */
+cv::Point3f CROSS(cv::Point3f v1, cv::Point3f v2)
+{
+  cv::Point3f tmp_p;
+  tmp_p.x =  v1.y*v2.z - v1.z*v2.y;
+  tmp_p.y =  v1.z*v2.x - v1.x*v2.z;
+  tmp_p.z =  v1.x*v2.y - v1.y*v2.x;
+  return tmp_p;
+}
+
+double DOT(cv::Point3f v1, cv::Point3f v2)
+{
+  return v1.x*v2.x + v1.y*v2.y + v1.z*v2.z;
+}
+
+cv::Point3f SUB(cv::Point3f v1, cv::Point3f v2)
+{
+  cv::Point3f tmp_p;
+  tmp_p.x =  v1.x - v2.x;
+  tmp_p.y =  v1.y - v2.y;
+  tmp_p.z =  v1.z - v2.z;
+  return tmp_p;
+}
+
+/* End functions for Möller–Trumbore intersection algorithm
+ *  */
+
+// Function to get the nearest 3D point to the Ray origin
+cv::Point3f get_nearest_3D_point(std::vector<cv::Point3f> &points_list, cv::Point3f origin)
+{
+  cv::Point3f p1 = points_list[0];
+  cv::Point3f p2 = points_list[1];
+
+  double d1 = std::sqrt( std::pow(p1.x-origin.x, 2) + std::pow(p1.y-origin.y, 2) + std::pow(p1.z-origin.z, 2) );
+  double d2 = std::sqrt( std::pow(p2.x-origin.x, 2) + std::pow(p2.y-origin.y, 2) + std::pow(p2.z-origin.z, 2) );
+
+  if(d1 < d2)
+  {
+      return p1;
+  }
+  else
+  {
+      return p2;
+  }
+}
+
+// Custom constructor given the intrinsic camera parameters
+
+PnPProblem::PnPProblem(const double params[])
+{
+  _A_matrix = cv::Mat::zeros(3, 3, CV_64FC1);   // intrinsic camera parameters
+  _A_matrix.at<double>(0, 0) = params[0];       //      [ fx   0  cx ]
+  _A_matrix.at<double>(1, 1) = params[1];       //      [  0  fy  cy ]
+  _A_matrix.at<double>(0, 2) = params[2];       //      [  0   0   1 ]
+  _A_matrix.at<double>(1, 2) = params[3];
+  _A_matrix.at<double>(2, 2) = 1;
+  _R_matrix = cv::Mat::zeros(3, 3, CV_64FC1);   // rotation matrix
+  _t_matrix = cv::Mat::zeros(3, 1, CV_64FC1);   // translation matrix
+  _P_matrix = cv::Mat::zeros(3, 4, CV_64FC1);   // rotation-translation matrix
+
+}
+
+PnPProblem::~PnPProblem()
+{
+  // TODO Auto-generated destructor stub
+}
+
+void PnPProblem::set_P_matrix( const cv::Mat &R_matrix, const cv::Mat &t_matrix)
+{
+  // Rotation-Translation Matrix Definition
+  _P_matrix.at<double>(0,0) = R_matrix.at<double>(0,0);
+  _P_matrix.at<double>(0,1) = R_matrix.at<double>(0,1);
+  _P_matrix.at<double>(0,2) = R_matrix.at<double>(0,2);
+  _P_matrix.at<double>(1,0) = R_matrix.at<double>(1,0);
+  _P_matrix.at<double>(1,1) = R_matrix.at<double>(1,1);
+  _P_matrix.at<double>(1,2) = R_matrix.at<double>(1,2);
+  _P_matrix.at<double>(2,0) = R_matrix.at<double>(2,0);
+  _P_matrix.at<double>(2,1) = R_matrix.at<double>(2,1);
+  _P_matrix.at<double>(0,3) = t_matrix.at<double>(0);
+  _P_matrix.at<double>(1,3) = t_matrix.at<double>(1);
+  _P_matrix.at<double>(2,3) = t_matrix.at<double>(2);
+}
+
+
+// Estimate the pose given a list of 2D/3D correspondences and the method to use
+bool PnPProblem::estimatePose( const std::vector<cv::Point3f> &list_points3d,
+                               const std::vector<cv::Point2f> &list_points2d,
+                               int flags)
+{
+  cv::Mat distCoeffs = cv::Mat::zeros(4, 1, CV_64FC1);
+  cv::Mat rvec = cv::Mat::zeros(3, 1, CV_64FC1);
+  cv::Mat tvec = cv::Mat::zeros(3, 1, CV_64FC1);
+
+  bool useExtrinsicGuess = false;
+
+  // Pose estimation
+  bool correspondence = cv::solvePnP( list_points3d, list_points2d, _A_matrix, distCoeffs, rvec, tvec,
+                                      useExtrinsicGuess, flags);
+
+  // Transforms Rotation Vector to Matrix
+  Rodrigues(rvec,_R_matrix);
+  _t_matrix = tvec;
+
+  // Set projection matrix
+  this->set_P_matrix(_R_matrix, _t_matrix);
+
+  return correspondence;
+}
+
+// Estimate the pose given a list of 2D/3D correspondences with RANSAC and the method to use
+
+void PnPProblem::estimatePoseRANSAC( const std::vector<cv::Point3f> &list_points3d, // list with model 3D coordinates
+                               const std::vector<cv::Point2f> &list_points2d,     // list with scene 2D coordinates
+                               int flags, cv::Mat &inliers, int iterationsCount,  // PnP method; inliers container
+                               float reprojectionError, float confidence )    // Ransac parameters
+{
+  cv::Mat distCoeffs = cv::Mat::zeros(4, 1, CV_64FC1);  // vector of distortion coefficients
+  cv::Mat rvec = cv::Mat::zeros(3, 1, CV_64FC1);          // output rotation vector
+  cv::Mat tvec = cv::Mat::zeros(3, 1, CV_64FC1);    // output translation vector
+
+  bool useExtrinsicGuess = false;   // if true the function uses the provided rvec and tvec values as
+            // initial approximations of the rotation and translation vectors
+
+  cv::solvePnPRansac( list_points3d, list_points2d, _A_matrix, distCoeffs, rvec, tvec,
+                useExtrinsicGuess, iterationsCount, reprojectionError, confidence,
+                inliers, flags );
+
+  Rodrigues(rvec,_R_matrix);      // converts Rotation Vector to Matrix
+  _t_matrix = tvec;       // set translation matrix
+
+  this->set_P_matrix(_R_matrix, _t_matrix); // set rotation-translation matrix
+
+}
+
+// Given the mesh, backproject the 3D points to 2D to verify the pose estimation
+std::vector<cv::Point2f> PnPProblem::verify_points(Mesh *mesh)
+{
+  std::vector<cv::Point2f> verified_points_2d;
+  for( int i = 0; i < mesh->getNumVertices(); i++)
+  {
+    cv::Point3f point3d = mesh->getVertex(i);
+    cv::Point2f point2d = this->backproject3DPoint(point3d);
+    verified_points_2d.push_back(point2d);
+  }
+
+  return verified_points_2d;
+}
+
+
+// Backproject a 3D point to 2D using the estimated pose parameters
+
+cv::Point2f PnPProblem::backproject3DPoint(const cv::Point3f &point3d)
+{
+  // 3D point vector [x y z 1]'
+  cv::Mat point3d_vec = cv::Mat(4, 1, CV_64FC1);
+  point3d_vec.at<double>(0) = point3d.x;
+  point3d_vec.at<double>(1) = point3d.y;
+  point3d_vec.at<double>(2) = point3d.z;
+  point3d_vec.at<double>(3) = 1;
+
+  // 2D point vector [u v 1]'
+  cv::Mat point2d_vec = cv::Mat(4, 1, CV_64FC1);
+  point2d_vec = _A_matrix * _P_matrix * point3d_vec;
+
+  // Normalization of [u v]'
+  cv::Point2f point2d;
+  point2d.x = point2d_vec.at<double>(0) / point2d_vec.at<double>(2);
+  point2d.y = point2d_vec.at<double>(1) / point2d_vec.at<double>(2);
+
+  return point2d;
+}
+
+// Back project a 2D point to 3D and returns if it's on the object surface
+bool PnPProblem::backproject2DPoint(const Mesh *mesh, const cv::Point2f &point2d, cv::Point3f &point3d)
+{
+  // Triangles list of the object mesh
+  std::vector<std::vector<int> > triangles_list = mesh->getTrianglesList();
+
+  double lambda = 8;
+  double u = point2d.x;
+  double v = point2d.y;
+
+  // Point in vector form
+  cv::Mat point2d_vec = cv::Mat::ones(3, 1, CV_64F); // 3x1
+  point2d_vec.at<double>(0) = u * lambda;
+  point2d_vec.at<double>(1) = v * lambda;
+  point2d_vec.at<double>(2) = lambda;
+
+  // Point in camera coordinates
+  cv::Mat X_c = _A_matrix.inv() * point2d_vec ; // 3x1
+
+  // Point in world coordinates
+  cv::Mat X_w = _R_matrix.inv() * ( X_c - _t_matrix ); // 3x1
+
+  // Center of projection
+  cv::Mat C_op = cv::Mat(_R_matrix.inv()).mul(-1) * _t_matrix; // 3x1
+
+  // Ray direction vector
+  cv::Mat ray = X_w - C_op; // 3x1
+  ray = ray / cv::norm(ray); // 3x1
+
+  // Set up Ray
+  Ray R((cv::Point3f)C_op, (cv::Point3f)ray);
+
+  // A vector to store the intersections found
+  std::vector<cv::Point3f> intersections_list;
+
+  // Loop for all the triangles and check the intersection
+  for (unsigned int i = 0; i < triangles_list.size(); i++)
+  {
+    cv::Point3f V0 = mesh->getVertex(triangles_list[i][0]);
+    cv::Point3f V1 = mesh->getVertex(triangles_list[i][1]);
+    cv::Point3f V2 = mesh->getVertex(triangles_list[i][2]);
+
+    Triangle T(i, V0, V1, V2);
+
+    double out;
+    if(this->intersect_MollerTrumbore(R, T, &out))
+    {
+      cv::Point3f tmp_pt = R.getP0() + out*R.getP1(); // P = O + t*D
+      intersections_list.push_back(tmp_pt);
+    }
+  }
+
+  // If there are intersection, find the nearest one
+  if (!intersections_list.empty())
+  {
+    point3d = get_nearest_3D_point(intersections_list, R.getP0());
+    return true;
+  }
+  else
+  {
+    return false;
+  }
+}
+
+// Möller–Trumbore intersection algorithm
+bool PnPProblem::intersect_MollerTrumbore(Ray &Ray, Triangle &Triangle, double *out)
+{
+  const double EPSILON = 0.000001;
+
+  cv::Point3f e1, e2;
+  cv::Point3f P, Q, T;
+  double det, inv_det, u, v;
+  double t;
+
+  cv::Point3f V1 = Triangle.getV0();  // Triangle vertices
+  cv::Point3f V2 = Triangle.getV1();
+  cv::Point3f V3 = Triangle.getV2();
+
+  cv::Point3f O = Ray.getP0(); // Ray origin
+  cv::Point3f D = Ray.getP1(); // Ray direction
+
+  //Find vectors for two edges sharing V1
+  e1 = SUB(V2, V1);
+  e2 = SUB(V3, V1);
+
+  // Begin calculation determinant - also used to calculate U parameter
+  P = CROSS(D, e2);
+
+  // If determinant is near zero, ray lie in plane of triangle
+  det = DOT(e1, P);
+
+  //NOT CULLING
+  if(det > -EPSILON && det < EPSILON) return false;
+  inv_det = 1.f / det;
+
+  //calculate distance from V1 to ray origin
+  T = SUB(O, V1);
+
+  //Calculate u parameter and test bound
+  u = DOT(T, P) * inv_det;
+
+  //The intersection lies outside of the triangle
+  if(u < 0.f || u > 1.f) return false;
+
+  //Prepare to test v parameter
+  Q = CROSS(T, e1);
+
+  //Calculate V parameter and test bound
+  v = DOT(D, Q) * inv_det;
+
+  //The intersection lies outside of the triangle
+  if(v < 0.f || u + v  > 1.f) return false;
+
+  t = DOT(e2, Q) * inv_det;
+
+  if(t > EPSILON) { //ray intersection
+    *out = t;
+    return true;
+  }
+
+  // No hit, no win
+  return false;
+}
+
+
+