| // Ceres Solver - A fast non-linear least squares minimizer | 
 | // Copyright 2015 Google Inc. All rights reserved. | 
 | // http://ceres-solver.org/ | 
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 | // | 
 | // Author: sameeragarwal@google.com (Sameer Agarwal) | 
 | // | 
 | // Templated struct implementing the camera model and residual | 
 | // computation for bundle adjustment used by Noah Snavely's Bundler | 
 | // SfM system. This is also the camera model/residual for the bundle | 
 | // adjustment problems in the BAL dataset. It is templated so that we | 
 | // can use Ceres's automatic differentiation to compute analytic | 
 | // jacobians. | 
 | // | 
 | // For details see: http://phototour.cs.washington.edu/bundler/ | 
 | // and http://grail.cs.washington.edu/projects/bal/ | 
 |  | 
 | #ifndef CERES_EXAMPLES_SNAVELY_REPROJECTION_ERROR_H_ | 
 | #define CERES_EXAMPLES_SNAVELY_REPROJECTION_ERROR_H_ | 
 |  | 
 | #include "ceres/rotation.h" | 
 |  | 
 | namespace ceres { | 
 | namespace examples { | 
 |  | 
 | // Templated pinhole camera model for used with Ceres.  The camera is | 
 | // parameterized using 9 parameters: 3 for rotation, 3 for translation, 1 for | 
 | // focal length and 2 for radial distortion. The principal point is not modeled | 
 | // (i.e. it is assumed be located at the image center). | 
 | struct SnavelyReprojectionError { | 
 |   SnavelyReprojectionError(double observed_x, double observed_y) | 
 |       : observed_x(observed_x), observed_y(observed_y) {} | 
 |  | 
 |   template <typename T> | 
 |   bool operator()(const T* const camera, | 
 |                   const T* const point, | 
 |                   T* residuals) const { | 
 |     // camera[0,1,2] are the angle-axis rotation. | 
 |     T p[3]; | 
 |     AngleAxisRotatePoint(camera, point, p); | 
 |  | 
 |     // camera[3,4,5] are the translation. | 
 |     p[0] += camera[3]; | 
 |     p[1] += camera[4]; | 
 |     p[2] += camera[5]; | 
 |  | 
 |     // Compute the center of distortion. The sign change comes from | 
 |     // the camera model that Noah Snavely's Bundler assumes, whereby | 
 |     // the camera coordinate system has a negative z axis. | 
 |     const T xp = -p[0] / p[2]; | 
 |     const T yp = -p[1] / p[2]; | 
 |  | 
 |     // Apply second and fourth order radial distortion. | 
 |     const T& l1 = camera[7]; | 
 |     const T& l2 = camera[8]; | 
 |     const T r2 = xp * xp + yp * yp; | 
 |     const T distortion = 1.0 + r2 * (l1 + l2 * r2); | 
 |  | 
 |     // Compute final projected point position. | 
 |     const T& focal = camera[6]; | 
 |     const T predicted_x = focal * distortion * xp; | 
 |     const T predicted_y = focal * distortion * yp; | 
 |  | 
 |     // The error is the difference between the predicted and observed position. | 
 |     residuals[0] = predicted_x - observed_x; | 
 |     residuals[1] = predicted_y - observed_y; | 
 |  | 
 |     return true; | 
 |   } | 
 |  | 
 |   // Factory to hide the construction of the CostFunction object from | 
 |   // the client code. | 
 |   static ceres::CostFunction* Create(const double observed_x, | 
 |                                      const double observed_y) { | 
 |     return (new ceres::AutoDiffCostFunction<SnavelyReprojectionError, 2, 9, 3>( | 
 |         new SnavelyReprojectionError(observed_x, observed_y))); | 
 |   } | 
 |  | 
 |   double observed_x; | 
 |   double observed_y; | 
 | }; | 
 |  | 
 | // Templated pinhole camera model for used with Ceres.  The camera is | 
 | // parameterized using 10 parameters. 4 for rotation, 3 for | 
 | // translation, 1 for focal length and 2 for radial distortion. The | 
 | // principal point is not modeled (i.e. it is assumed be located at | 
 | // the image center). | 
 | struct SnavelyReprojectionErrorWithQuaternions { | 
 |   // (u, v): the position of the observation with respect to the image | 
 |   // center point. | 
 |   SnavelyReprojectionErrorWithQuaternions(double observed_x, double observed_y) | 
 |       : observed_x(observed_x), observed_y(observed_y) {} | 
 |  | 
 |   template <typename T> | 
 |   bool operator()(const T* const camera, | 
 |                   const T* const point, | 
 |                   T* residuals) const { | 
 |     // camera[0,1,2,3] is are the rotation of the camera as a quaternion. | 
 |     // | 
 |     // We use QuaternionRotatePoint as it does not assume that the | 
 |     // quaternion is normalized, since one of the ways to run the | 
 |     // bundle adjuster is to let Ceres optimize all 4 quaternion | 
 |     // parameters without a local parameterization. | 
 |     T p[3]; | 
 |     QuaternionRotatePoint(camera, point, p); | 
 |  | 
 |     p[0] += camera[4]; | 
 |     p[1] += camera[5]; | 
 |     p[2] += camera[6]; | 
 |  | 
 |     // Compute the center of distortion. The sign change comes from | 
 |     // the camera model that Noah Snavely's Bundler assumes, whereby | 
 |     // the camera coordinate system has a negative z axis. | 
 |     const T xp = -p[0] / p[2]; | 
 |     const T yp = -p[1] / p[2]; | 
 |  | 
 |     // Apply second and fourth order radial distortion. | 
 |     const T& l1 = camera[8]; | 
 |     const T& l2 = camera[9]; | 
 |  | 
 |     const T r2 = xp * xp + yp * yp; | 
 |     const T distortion = 1.0 + r2 * (l1 + l2 * r2); | 
 |  | 
 |     // Compute final projected point position. | 
 |     const T& focal = camera[7]; | 
 |     const T predicted_x = focal * distortion * xp; | 
 |     const T predicted_y = focal * distortion * yp; | 
 |  | 
 |     // The error is the difference between the predicted and observed position. | 
 |     residuals[0] = predicted_x - observed_x; | 
 |     residuals[1] = predicted_y - observed_y; | 
 |  | 
 |     return true; | 
 |   } | 
 |  | 
 |   // Factory to hide the construction of the CostFunction object from | 
 |   // the client code. | 
 |   static ceres::CostFunction* Create(const double observed_x, | 
 |                                      const double observed_y) { | 
 |     return ( | 
 |         new ceres::AutoDiffCostFunction<SnavelyReprojectionErrorWithQuaternions, | 
 |                                         2, | 
 |                                         10, | 
 |                                         3>( | 
 |             new SnavelyReprojectionErrorWithQuaternions(observed_x, | 
 |                                                         observed_y))); | 
 |   } | 
 |  | 
 |   double observed_x; | 
 |   double observed_y; | 
 | }; | 
 |  | 
 | }  // namespace examples | 
 | }  // namespace ceres | 
 |  | 
 | #endif  // CERES_EXAMPLES_SNAVELY_REPROJECTION_ERROR_H_ |