colmap/src/base/database_cache.cc

// Copyright (c) 2022, ETH Zurich and UNC Chapel Hill.
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// Author: Johannes L. Schoenberger (jsch-at-demuc-dot-de)

#include "base/database_cache.h"

#include <unordered_set>

#include "feature/utils.h"
#include "util/string.h"
#include "util/timer.h"

namespace colmap {

DatabaseCache::DatabaseCache() {}

void DatabaseCache::AddCamera(class Camera camera) {
  const camera_t camera_id = camera.CameraId();
  CHECK(!ExistsCamera(camera_id));
  cameras_.emplace(camera_id, std::move(camera));
}

void DatabaseCache::AddImage(class Image image) {
  const image_t image_id = image.ImageId();
  CHECK(!ExistsImage(image_id));
  correspondence_graph_.AddImage(image_id, image.NumPoints2D());
  images_.emplace(image_id, std::move(image));
}

void DatabaseCache::Load(const Database& database, const size_t min_num_matches,
                         const bool ignore_watermarks,
                         const std::unordered_set<std::string>& image_names) {
  //////////////////////////////////////////////////////////////////////////////
  // Load cameras
  //////////////////////////////////////////////////////////////////////////////

  Timer timer;

  timer.Start();
  std::cout << "Loading cameras..." << std::flush;

  {
    std::vector<class Camera> cameras = database.ReadAllCameras();
    cameras_.reserve(cameras.size());
    for (auto& camera : cameras) {
      const camera_t camera_id = camera.CameraId();
      cameras_.emplace(camera_id, std::move(camera));
    }
  }

  std::cout << StringPrintf(" %d in %.3fs", cameras_.size(),
                            timer.ElapsedSeconds())
            << std::endl;

  //////////////////////////////////////////////////////////////////////////////
  // Load matches
  //////////////////////////////////////////////////////////////////////////////

  timer.Restart();
  std::cout << "Loading matches..." << std::flush;

  std::vector<image_pair_t> image_pair_ids;
  std::vector<TwoViewGeometry> two_view_geometries;
  database.ReadTwoViewGeometries(&image_pair_ids, &two_view_geometries);

  std::cout << StringPrintf(" %d in %.3fs", image_pair_ids.size(),
                            timer.ElapsedSeconds())
            << std::endl;

  auto UseInlierMatchesCheck = [min_num_matches, ignore_watermarks](
                                   const TwoViewGeometry& two_view_geometry) {
    return static_cast<size_t>(two_view_geometry.inlier_matches.size()) >=
               min_num_matches &&
           (!ignore_watermarks ||
            two_view_geometry.config != TwoViewGeometry::WATERMARK);
  };

  //////////////////////////////////////////////////////////////////////////////
  // Load images
  //////////////////////////////////////////////////////////////////////////////

  timer.Restart();
  std::cout << "Loading images..." << std::flush;

  std::unordered_set<image_t> image_ids;

  {
    std::vector<class Image> images = database.ReadAllImages();
    const size_t num_images = images.size();

    // Determines for which images data should be loaded.
    if (image_names.empty()) {
      for (const auto& image : images) {
        image_ids.insert(image.ImageId());
      }
    } else {
      for (const auto& image : images) {
        if (image_names.count(image.Name()) > 0) {
          image_ids.insert(image.ImageId());
        }
      }
    }

    // Collect all images that are connected in the correspondence graph.
    std::unordered_set<image_t> connected_image_ids;
    connected_image_ids.reserve(image_ids.size());
    for (size_t i = 0; i < image_pair_ids.size(); ++i) {
      if (UseInlierMatchesCheck(two_view_geometries[i])) {
        image_t image_id1;
        image_t image_id2;
        Database::PairIdToImagePair(image_pair_ids[i], &image_id1, &image_id2);
        if (image_ids.count(image_id1) > 0 && image_ids.count(image_id2) > 0) {
          connected_image_ids.insert(image_id1);
          connected_image_ids.insert(image_id2);
        }
      }
    }

    // Load images with correspondences and discard images without
    // correspondences, as those images are useless for SfM.
    images_.reserve(connected_image_ids.size());
    for (auto& image : images) {
      const image_t image_id = image.ImageId();
      if (image_ids.count(image_id) > 0 &&
          connected_image_ids.count(image_id) > 0) {
        images_.emplace(image_id, std::move(image));
        const FeatureKeypoints keypoints = database.ReadKeypoints(image_id);
        const std::vector<Eigen::Vector2d> points =
            FeatureKeypointsToPointsVector(keypoints);
        images_[image_id].SetPoints2D(points);
      }
    }

    std::cout << StringPrintf(" %d in %.3fs (connected %d)", num_images,
                              timer.ElapsedSeconds(),
                              connected_image_ids.size())
              << std::endl;
  }

  //////////////////////////////////////////////////////////////////////////////
  // Build correspondence graph
  //////////////////////////////////////////////////////////////////////////////

  timer.Restart();
  std::cout << "Building correspondence graph..." << std::flush;

  for (const auto& image : images_) {
    correspondence_graph_.AddImage(image.first, image.second.NumPoints2D());
  }

  size_t num_ignored_image_pairs = 0;
  for (size_t i = 0; i < image_pair_ids.size(); ++i) {
    if (UseInlierMatchesCheck(two_view_geometries[i])) {
      image_t image_id1;
      image_t image_id2;
      Database::PairIdToImagePair(image_pair_ids[i], &image_id1, &image_id2);
      if (image_ids.count(image_id1) > 0 && image_ids.count(image_id2) > 0) {
        correspondence_graph_.AddCorrespondences(
            image_id1, image_id2, two_view_geometries[i].inlier_matches);
      } else {
        num_ignored_image_pairs += 1;
      }
    } else {
      num_ignored_image_pairs += 1;
    }
  }

  correspondence_graph_.Finalize();

  // Set number of observations and correspondences per image.
  for (auto& image : images_) {
    image.second.SetNumObservations(
        correspondence_graph_.NumObservationsForImage(image.first));
    image.second.SetNumCorrespondences(
        correspondence_graph_.NumCorrespondencesForImage(image.first));
  }

  std::cout << StringPrintf(" in %.3fs (ignored %d)", timer.ElapsedSeconds(),
                            num_ignored_image_pairs)
            << std::endl;
}

const class Image* DatabaseCache::FindImageWithName(
    const std::string& name) const {
  for (const auto& image : images_) {
    if (image.second.Name() == name) {
      return &image.second;
    }
  }
  return nullptr;
}

}  // namespace colmap