vpPixelMeterConversion.h

/*
 * ViSP, open source Visual Servoing Platform software.
 * Copyright (C) 2005 - 2025 by Inria. All rights reserved.
 *
 * This software is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * See the file LICENSE.txt at the root directory of this source
 * distribution for additional information about the GNU GPL.
 *
 * For using ViSP with software that can not be combined with the GNU
 * GPL, please contact Inria about acquiring a ViSP Professional
 * Edition License.
 *
 * See https://visp.inria.fr for more information.
 *
 * This software was developed at:
 * Inria Rennes - Bretagne Atlantique
 * Campus Universitaire de Beaulieu
 * 35042 Rennes Cedex
 * France
 *
 * If you have questions regarding the use of this file, please contact
 * Inria at visp@inria.fr
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Description:
 * Pixel to meter conversion.
 */

 
#ifndef VP_PIXEL_METER_CONVERSION_H
#define VP_PIXEL_METER_CONVERSION_H
 
#include <visp3/core/vpCameraParameters.h>
#include <visp3/core/vpException.h>
#include <visp3/core/vpImagePoint.h>
#include <visp3/core/vpMath.h>
 
#if defined(VISP_HAVE_OPENCV)
#include <opencv2/core/core.hpp>
#endif
 
BEGIN_VISP_NAMESPACE
class VISP_EXPORT vpPixelMeterConversion
{
public:
  static void convertEllipse(const vpCameraParameters &cam, const vpImagePoint &center_p, double n20_p, double n11_p,
                             double n02_p, double &xc_m, double &yc_m, double &n20_m, double &n11_m, double &n02_m);
  static void convertLine(const vpCameraParameters &cam, const double &rho_p, const double &theta_p, double &rho_m,
                          double &theta_m);
 
  static void convertMoment(const vpCameraParameters &cam, unsigned int order, const vpMatrix &moment_pixel,
                            vpMatrix &moment_meter);
  inline static void convertPoint(const vpCameraParameters &cam, const double &u, const double &v, double &x, double &y)
  {
    switch (cam.m_projModel) {
    case vpCameraParameters::perspectiveProjWithoutDistortion:
      convertPointWithoutDistortion(cam, u, v, x, y);
      break;
    case vpCameraParameters::perspectiveProjWithDistortion:
      convertPointWithDistortion(cam, u, v, x, y);
      break;
    case vpCameraParameters::ProjWithKannalaBrandtDistortion:
      convertPointWithKannalaBrandtDistortion(cam, u, v, x, y);
      break;
    default: {
      throw(vpException(vpException::fatalError, "Unsupported camera projection model in vpPixelMerterConversion::convertPoint()"));
    }
    }
  }

  inline static void convertPoint(const vpCameraParameters &cam, const vpImagePoint &iP, double &x, double &y)
  {
    switch (cam.m_projModel) {
    case vpCameraParameters::perspectiveProjWithoutDistortion:
      convertPointWithoutDistortion(cam, iP, x, y);
      break;
    case vpCameraParameters::perspectiveProjWithDistortion:
      convertPointWithDistortion(cam, iP, x, y);
      break;
    case vpCameraParameters::ProjWithKannalaBrandtDistortion:
      convertPointWithKannalaBrandtDistortion(cam, iP, x, y);
      break;
    default: {
      throw(vpException(vpException::fatalError, "Unsupported camera projection model in vpPixelMerterConversion::convertPoint()"));
    }
    }
  }
 
#ifndef DOXYGEN_SHOULD_SKIP_THIS
  inline static void convertPointWithoutDistortion(const vpCameraParameters &cam, const double &u, const double &v,
                                                   double &x, double &y)
  {
    x = (u - cam.m_u0) * cam.m_inv_px;
    y = (v - cam.m_v0) * cam.m_inv_py;
  }

  inline static void convertPointWithoutDistortion(const vpCameraParameters &cam, const vpImagePoint &iP, double &x,
                                                   double &y)
  {
    x = (iP.get_u() - cam.m_u0) * cam.m_inv_px;
    y = (iP.get_v() - cam.m_v0) * cam.m_inv_py;
  }

  inline static void convertPointWithDistortion(const vpCameraParameters &cam, const double &u, const double &v,
                                                double &x, double &y)
  {
    double r2 = 1. + (cam.m_kdu * (vpMath::sqr((u - cam.m_u0) * cam.m_inv_px) + vpMath::sqr((v - cam.m_v0) * cam.m_inv_py)));
    x = (u - cam.m_u0) * r2 * cam.m_inv_px;
    y = (v - cam.m_v0) * r2 * cam.m_inv_py;
  }

  inline static void convertPointWithDistortion(const vpCameraParameters &cam, const vpImagePoint &iP, double &x,
                                                double &y)
  {
    double r2 = 1. + (cam.m_kdu * (vpMath::sqr((iP.get_u() - cam.m_u0) * cam.m_inv_px) +
                                   vpMath::sqr((iP.get_v() - cam.m_v0) * cam.m_inv_py)));
    x = (iP.get_u() - cam.m_u0) * r2 * cam.m_inv_px;
    y = (iP.get_v() - cam.m_v0) * r2 * cam.m_inv_py;
  }

  inline static void convertPointWithKannalaBrandtDistortion(const vpCameraParameters &cam, const double &u,
                                                             const double &v, double &x, double &y)
  {
    double x_d = (u - cam.m_u0) / cam.m_px, y_d = (v - cam.m_v0) / cam.m_py;
    double scale = 1.0;
    double r_d = sqrt(vpMath::sqr(x_d) + vpMath::sqr(y_d));
    const unsigned int index_0 = 0;
    const unsigned int index_1 = 1;
    const unsigned int index_2 = 2;
    const unsigned int index_3 = 3;
    const unsigned int val_1 = 1;
    const unsigned int val_3 = 3;
    const unsigned int val_5 = 5;
    const unsigned int val_7 = 7;
    const unsigned int val_9 = 9;
    const unsigned int val_10 = 10;
 
    r_d = std::min<double>(std::max<double>(-M_PI, r_d), M_PI); // FOV restricted to 180degrees.
 
    std::vector<double> k = cam.getKannalaBrandtDistortionCoefficients();
 
    const double EPS = 1e-8;
    // Use Newton-Raphson method to solve for the angle theta
    if (r_d > EPS) {
      // compensate distortion iteratively
      double theta = r_d;
 
      for (unsigned int j = 0; j < val_10; ++j) {
        double theta2 = theta * theta;
        double theta4 = theta2 * theta2;
        double theta6 = theta4 * theta2;
        double theta8 = theta6 * theta2;
        double k0_theta2 = k[index_0] * theta2;
        double k1_theta4 = k[index_1] * theta4;
        double k2_theta6 = k[index_2] * theta6,
          k3_theta8 = k[index_3] * theta8;
          /*
          // new_theta = theta - theta_fix, theta_fix = f0(theta) / f0'(theta)
          */
        double theta_fix = ((theta * (val_1 + k0_theta2 + k1_theta4 + k2_theta6 + k3_theta8)) - r_d)
          / (val_1 + (val_3 * k0_theta2) + (val_5 * k1_theta4) + (val_7 * k2_theta6) + (val_9 * k3_theta8));
        theta = theta - theta_fix;
        if (fabs(theta_fix) < EPS) {
          break;
        }
      }
 
      scale = std::tan(theta) / r_d; // Scale of norm of (x,y) and (x_d, y_d)
    }
 
    x = x_d * scale;
    y = y_d * scale;
  }

  inline static void convertPointWithKannalaBrandtDistortion(const vpCameraParameters &cam, const vpImagePoint &iP,
                                                             double &x, double &y)
  {
    double x_d = (iP.get_u() - cam.m_u0) / cam.m_px, y_d = (iP.get_v() - cam.m_v0) / cam.m_py;
    double scale = 1.0;
    double r_d = sqrt(vpMath::sqr(x_d) + vpMath::sqr(y_d));
    const unsigned int index_0 = 0;
    const unsigned int index_1 = 1;
    const unsigned int index_2 = 2;
    const unsigned int index_3 = 3;
    const unsigned int val_1 = 1;
    const unsigned int val_3 = 3;
    const unsigned int val_5 = 5;
    const unsigned int val_7 = 7;
    const unsigned int val_9 = 9;
    const unsigned int val_10 = 10;
 
    r_d = std::min<double>(std::max<double>(-M_PI, r_d), M_PI); // FOV restricted to 180degrees.
 
    std::vector<double> k = cam.getKannalaBrandtDistortionCoefficients();
 
    const double EPS = 1e-8;
    // Use Newton-Raphson method to solve for the angle theta
    if (r_d > EPS) {
      // compensate distortion iteratively
      double theta = r_d;
 
      for (unsigned int j = 0; j < val_10; ++j) {
        double theta2 = theta * theta;
        double theta4 = theta2 * theta2;
        double theta6 = theta4 * theta2;
        double theta8 = theta6 * theta2;
        double k0_theta2 = k[index_0] * theta2;
        double k1_theta4 = k[index_1] * theta4;
        double k2_theta6 = k[index_2] * theta6;
        double k3_theta8 = k[index_3] * theta8;
        /*
          // new_theta = theta - theta_fix, theta_fix = f0(theta) / f0'(theta)
        */
        double theta_fix = ((theta * (val_1 + k0_theta2 + k1_theta4 + k2_theta6 + k3_theta8)) - r_d) /
          (val_1 + (val_3 * k0_theta2) + (val_5 * k1_theta4) + (val_7 * k2_theta6) + (val_9 * k3_theta8));
        theta = theta - theta_fix;
        if (fabs(theta_fix) < EPS) {
          break;
        }
      }
 
      scale = std::tan(theta) / r_d; // Scale of norm of (x,y) and (x_d, y_d)
    }
 
    x = x_d * scale;
    y = y_d * scale;
  }
#endif // #ifndef DOXYGEN_SHOULD_SKIP_THIS
 
#if defined(HAVE_OPENCV_IMGPROC) && \
  (((VISP_HAVE_OPENCV_VERSION < 0x050000) && defined(HAVE_OPENCV_CALIB3D)) || ((VISP_HAVE_OPENCV_VERSION >= 0x050000) && defined(HAVE_OPENCV_CALIB) && defined(HAVE_OPENCV_3D)))

  static void convertEllipse(const cv::Mat &cameraMatrix, const cv::Mat &distCoeffs, const vpImagePoint &center_p,
                             double n20_p, double n11_p, double n02_p, double &xc_m, double &yc_m, double &n20_m,
                             double &n11_m, double &n02_m);
  static void convertLine(const cv::Mat &cameraMatrix, const double &rho_p, const double &theta_p, double &rho_m,
                          double &theta_m);
  static void convertMoment(const cv::Mat &cameraMatrix, unsigned int order, const vpMatrix &moment_pixel,
                            vpMatrix &moment_meter);
  static void convertPoint(const cv::Mat &cameraMatrix, const cv::Mat &distCoeffs, const double &u, const double &v,
                           double &x, double &y);
  static void convertPoint(const cv::Mat &cameraMatrix, const cv::Mat &distCoeffs, const vpImagePoint &iP, double &x,
                           double &y);
#endif
};
END_VISP_NAMESPACE
#endif