fusion.h

// COLMAP - Structure-from-Motion and Multi-View Stereo.
// Copyright (C) 2017  Johannes L. Schoenberger <jsch at inf.ethz.ch>
//
// This program 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 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

#ifndef COLMAP_SRC_MVS_FUSION_H_
#define COLMAP_SRC_MVS_FUSION_H_

#include <vector>

#include <Eigen/Core>

#include "mvs/depth_map.h"
#include "mvs/image.h"
#include "mvs/mat.h"
#include "mvs/model.h"
#include "mvs/normal_map.h"
#include "mvs/workspace.h"
#include "util/alignment.h"
#include "util/cache.h"
#include "util/math.h"
#include "util/threading.h"

namespace colmap {
namespace mvs {

struct FusedPoint {
  float x = 0.0f;
  float y = 0.0f;
  float z = 0.0f;
  float nx = 0.0f;
  float ny = 0.0f;
  float nz = 0.0f;
  uint8_t r = 0;
  uint8_t g = 0;
  uint8_t b = 0;
};

class StereoFusion : public Thread {
 public:
  EIGEN_MAKE_ALIGNED_OPERATOR_NEW

  struct Options {
    // Minimum number of fused pixels to produce a point.
    int min_num_pixels = 5;

    // Maximum number of pixels to fuse into a single point.
    int max_num_pixels = 1000;

    // Maximum depth in consistency graph traversal.
    int max_traversal_depth = 100;

    // Maximum relative difference between measured and projected pixel.
    double max_reproj_error = 2.0f;

    // Maximum relative difference between measured and projected depth.
    double max_depth_error = 0.01f;

    // Maximum difference between normals of pixels to be fused.
    double max_normal_error = 10.0f;

    // Cache size for fusion. The fusion keeps the bitmaps, depth maps, normal
    // maps, and consistency graphs of this number of images in memory. A higher
    // value here leads to less disk access and faster fusion, while a larger
    // value leads to reduced memory usage. Note that a single image can consume
    // a lot of memory, if the consistency graph is dense.
    int cache_size = 250;

    // Check the options for validity.
    bool Check() const;

    // Print the options to stdout.
    void Print() const;
  };

  StereoFusion(const Options& options, const std::string& workspace_path,
               const std::string& workspace_format,
               const std::string& input_type);

  const std::vector<FusedPoint>& GetFusedPoints() const;

 private:
  void Run();
  void Fuse();

  const Options options_;
  const std::string workspace_path_;
  const std::string workspace_format_;
  const std::string input_type_;
  const float max_squared_reproj_error_;
  const float min_cos_normal_error_;

  std::unique_ptr<Workspace> workspace_;
  std::vector<char> used_images_;
  std::vector<Mat<bool>> visited_masks_;
  std::vector<std::pair<int, int>> depth_map_sizes_;
  std::vector<std::pair<float, float>> bitmap_scales_;
  std::vector<Eigen::Matrix<float, 3, 4, Eigen::RowMajor>> P_;
  std::vector<Eigen::Matrix<float, 3, 4, Eigen::RowMajor>> inv_P_;
  std::vector<Eigen::Matrix<float, 3, 3, Eigen::RowMajor>> inv_R_;

  struct FusionData {
    int image_id = kInvalidImageId;
    int row = 0;
    int col = 0;
    int traversal_depth = -1;
  };

  std::queue<FusionData> fusion_queue_;
  std::vector<FusedPoint> fused_points_;
  std::vector<float> fused_points_x_;
  std::vector<float> fused_points_y_;
  std::vector<float> fused_points_z_;
  std::vector<float> fused_points_nx_;
  std::vector<float> fused_points_ny_;
  std::vector<float> fused_points_nz_;
  std::vector<uint8_t> fused_points_r_;
  std::vector<uint8_t> fused_points_g_;
  std::vector<uint8_t> fused_points_b_;
};

// Write the point cloud to PLY file.
void WritePlyText(const std::string& path,
                  const std::vector<FusedPoint>& points);
void WritePlyBinary(const std::string& path,
                    const std::vector<FusedPoint>& points);

}  // namespace mvs
}  // namespace colmap

#endif  // COLMAP_SRC_MVS_FUSION_H_