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Diffstat (limited to 'examples/simple_bundle_adjuster.cc')
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diff --git a/examples/simple_bundle_adjuster.cc b/examples/simple_bundle_adjuster.cc new file mode 100644 index 0000000..cc6f04a --- /dev/null +++ b/examples/simple_bundle_adjuster.cc @@ -0,0 +1,210 @@ +// Ceres Solver - A fast non-linear least squares minimizer +// Copyright 2010, 2011, 2012 Google Inc. All rights reserved. +// http://code.google.com/p/ceres-solver/ +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are met: +// +// * Redistributions of source code must retain the above copyright notice, +// this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above copyright notice, +// this list of conditions and the following disclaimer in the documentation +// and/or other materials provided with the distribution. +// * Neither the name of Google Inc. nor the names of its contributors may be +// used to endorse or promote products derived from this software without +// specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" +// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE +// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR +// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF +// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS +// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN +// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) +// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +// POSSIBILITY OF SUCH DAMAGE. +// +// Author: keir@google.com (Keir Mierle) +// +// A minimal, self-contained bundle adjuster using Ceres, that reads +// files from University of Washington' Bundle Adjustment in the Large dataset: +// http://grail.cs.washington.edu/projects/bal +// +// This does not use the best configuration for solving; see the more involved +// bundle_adjuster.cc file for details. + +#include <cmath> +#include <cstdio> +#include <iostream> + +#include "ceres/ceres.h" +#include "ceres/rotation.h" + +// Read a Bundle Adjustment in the Large dataset. +class BALProblem { + public: + ~BALProblem() { + delete[] point_index_; + delete[] camera_index_; + delete[] observations_; + delete[] parameters_; + } + + int num_observations() const { return num_observations_; } + const double* observations() const { return observations_; } + double* mutable_cameras() { return parameters_; } + double* mutable_points() { return parameters_ + 9 * num_cameras_; } + + double* mutable_camera_for_observation(int i) { + return mutable_cameras() + camera_index_[i] * 9; + } + double* mutable_point_for_observation(int i) { + return mutable_points() + point_index_[i] * 3; + } + + bool LoadFile(const char* filename) { + FILE* fptr = fopen(filename, "r"); + if (fptr == NULL) { + return false; + }; + + FscanfOrDie(fptr, "%d", &num_cameras_); + FscanfOrDie(fptr, "%d", &num_points_); + FscanfOrDie(fptr, "%d", &num_observations_); + + point_index_ = new int[num_observations_]; + camera_index_ = new int[num_observations_]; + observations_ = new double[2 * num_observations_]; + + num_parameters_ = 9 * num_cameras_ + 3 * num_points_; + parameters_ = new double[num_parameters_]; + + for (int i = 0; i < num_observations_; ++i) { + FscanfOrDie(fptr, "%d", camera_index_ + i); + FscanfOrDie(fptr, "%d", point_index_ + i); + for (int j = 0; j < 2; ++j) { + FscanfOrDie(fptr, "%lf", observations_ + 2*i + j); + } + } + + for (int i = 0; i < num_parameters_; ++i) { + FscanfOrDie(fptr, "%lf", parameters_ + i); + } + return true; + } + + private: + template<typename T> + void FscanfOrDie(FILE *fptr, const char *format, T *value) { + int num_scanned = fscanf(fptr, format, value); + if (num_scanned != 1) { + LOG(FATAL) << "Invalid UW data file."; + } + } + + int num_cameras_; + int num_points_; + int num_observations_; + int num_parameters_; + + int* point_index_; + int* camera_index_; + double* observations_; + double* parameters_; +}; + +// 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]; + ceres::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. + T xp = - p[0] / p[2]; + T yp = - p[1] / p[2]; + + // Apply second and fourth order radial distortion. + const T& l1 = camera[7]; + const T& l2 = camera[8]; + T r2 = xp*xp + yp*yp; + T distortion = T(1.0) + r2 * (l1 + l2 * r2); + + // Compute final projected point position. + const T& focal = camera[6]; + T predicted_x = focal * distortion * xp; + T predicted_y = focal * distortion * yp; + + // The error is the difference between the predicted and observed position. + residuals[0] = predicted_x - T(observed_x); + residuals[1] = predicted_y - T(observed_y); + + return true; + } + + double observed_x; + double observed_y; +}; + +int main(int argc, char** argv) { + google::InitGoogleLogging(argv[0]); + if (argc != 2) { + std::cerr << "usage: simple_bundle_adjuster <bal_problem>\n"; + return 1; + } + + BALProblem bal_problem; + if (!bal_problem.LoadFile(argv[1])) { + std::cerr << "ERROR: unable to open file " << argv[1] << "\n"; + return 1; + } + + // Create residuals for each observation in the bundle adjustment problem. The + // parameters for cameras and points are added automatically. + ceres::Problem problem; + for (int i = 0; i < bal_problem.num_observations(); ++i) { + // Each Residual block takes a point and a camera as input and outputs a 2 + // dimensional residual. Internally, the cost function stores the observed + // image location and compares the reprojection against the observation. + ceres::CostFunction* cost_function = + new ceres::AutoDiffCostFunction<SnavelyReprojectionError, 2, 9, 3>( + new SnavelyReprojectionError( + bal_problem.observations()[2 * i + 0], + bal_problem.observations()[2 * i + 1])); + + problem.AddResidualBlock(cost_function, + NULL /* squared loss */, + bal_problem.mutable_camera_for_observation(i), + bal_problem.mutable_point_for_observation(i)); + } + + // Make Ceres automatically detect the bundle structure. Note that the + // standard solver, SPARSE_NORMAL_CHOLESKY, also works fine but it is slower + // for standard bundle adjustment problems. + ceres::Solver::Options options; + options.linear_solver_type = ceres::DENSE_SCHUR; + options.minimizer_progress_to_stdout = true; + + ceres::Solver::Summary summary; + ceres::Solve(options, &problem, &summary); + std::cout << summary.FullReport() << "\n"; + return 0; +} |