colmap/src/ui/colormaps.cc

// Copyright (c) 2022, ETH Zurich and UNC Chapel Hill.
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// Author: Johannes L. Schoenberger (jsch-at-demuc-dot-de)

#include "ui/colormaps.h"

#include "util/bitmap.h"

namespace colmap {

PointColormapBase::PointColormapBase()
    : scale(1.0f),
      min(0.0f),
      max(0.0f),
      range(0.0f),
      min_q(0.0f),
      max_q(1.0f) {}

void PointColormapBase::UpdateScale(std::vector<float>* values) {
  if (values->empty()) {
    min = 0.0f;
    max = 0.0f;
    range = 0.0f;
  } else {
    std::sort(values->begin(), values->end());
    min = (*values)[static_cast<size_t>(min_q * (values->size() - 1))];
    max = (*values)[static_cast<size_t>(max_q * (values->size() - 1))];
    range = max - min;
  }
}

float PointColormapBase::AdjustScale(const float gray) {
  if (range == 0.0f) {
    return 0.0f;
  } else {
    const float gray_clipped = std::min(std::max(gray, min), max);
    const float gray_scaled = (gray_clipped - min) / range;
    return std::pow(gray_scaled, scale);
  }
}

void PointColormapPhotometric::Prepare(EIGEN_STL_UMAP(camera_t, Camera) &
                                           cameras,
                                       EIGEN_STL_UMAP(image_t, Image) & images,
                                       EIGEN_STL_UMAP(point3D_t, Point3D) &
                                           points3D,
                                       std::vector<image_t>& reg_image_ids) {}

Eigen::Vector4f PointColormapPhotometric::ComputeColor(
    const point3D_t point3D_id, const Point3D& point3D) {
  return Eigen::Vector4f(point3D.Color(0) / 255.0f, point3D.Color(1) / 255.0f,
                         point3D.Color(2) / 255.0f, 1.0f);
}

void PointColormapError::Prepare(EIGEN_STL_UMAP(camera_t, Camera) & cameras,
                                 EIGEN_STL_UMAP(image_t, Image) & images,
                                 EIGEN_STL_UMAP(point3D_t, Point3D) & points3D,
                                 std::vector<image_t>& reg_image_ids) {
  std::vector<float> errors;
  errors.reserve(points3D.size());

  for (const auto& point3D : points3D) {
    errors.push_back(static_cast<float>(point3D.second.Error()));
  }

  UpdateScale(&errors);
}

Eigen::Vector4f PointColormapError::ComputeColor(const point3D_t point3D_id,
                                                 const Point3D& point3D) {
  const float gray = AdjustScale(static_cast<float>(point3D.Error()));
  return Eigen::Vector4f(JetColormap::Red(gray), JetColormap::Green(gray),
                         JetColormap::Blue(gray), 1.0f);
}

void PointColormapTrackLen::Prepare(EIGEN_STL_UMAP(camera_t, Camera) & cameras,
                                    EIGEN_STL_UMAP(image_t, Image) & images,
                                    EIGEN_STL_UMAP(point3D_t, Point3D) &
                                        points3D,
                                    std::vector<image_t>& reg_image_ids) {
  std::vector<float> track_lengths;
  track_lengths.reserve(points3D.size());

  for (const auto& point3D : points3D) {
    track_lengths.push_back(point3D.second.Track().Length());
  }

  UpdateScale(&track_lengths);
}

Eigen::Vector4f PointColormapTrackLen::ComputeColor(const point3D_t point3D_id,
                                                    const Point3D& point3D) {
  const float gray = AdjustScale(point3D.Track().Length());
  return Eigen::Vector4f(JetColormap::Red(gray), JetColormap::Green(gray),
                         JetColormap::Blue(gray), 1.0f);
}

void PointColormapGroundResolution::Prepare(
    EIGEN_STL_UMAP(camera_t, Camera) & cameras,
    EIGEN_STL_UMAP(image_t, Image) & images,
    EIGEN_STL_UMAP(point3D_t, Point3D) & points3D,
    std::vector<image_t>& reg_image_ids) {
  std::vector<float> resolutions;
  resolutions.reserve(points3D.size());

  std::unordered_map<camera_t, float> focal_lengths;
  EIGEN_STL_UMAP(camera_t, Eigen::Vector2f) principal_points;
  for (const auto& camera : cameras) {
    focal_lengths[camera.first] =
        static_cast<float>(camera.second.MeanFocalLength());
    principal_points[camera.first] =
        Eigen::Vector2f(static_cast<float>(camera.second.PrincipalPointX()),
                        static_cast<float>(camera.second.PrincipalPointY()));
  }

  EIGEN_STL_UMAP(image_t, Eigen::Vector3f) proj_centers;
  for (const auto& image : images) {
    proj_centers[image.first] = image.second.ProjectionCenter().cast<float>();
  }

  for (const auto& point3D : points3D) {
    float min_resolution = std::numeric_limits<float>::max();

    const Eigen::Vector3f xyz = point3D.second.XYZ().cast<float>();

    for (const auto& track_el : point3D.second.Track().Elements()) {
      const auto& image = images[track_el.image_id];
      const float focal_length = focal_lengths[image.CameraId()];
      const float focal_length2 = focal_length * focal_length;
      const Eigen::Vector2f& pp = principal_points[image.CameraId()];

      const Eigen::Vector2f xy =
          image.Point2D(track_el.point2D_idx).XY().cast<float>() - pp;

      // Distance from principal point to observation on image plane.
      const float pixel_radius1 = xy.norm();

      const float x1 = xy(0) + (xy(0) < 0 ? -1.0f : 1.0f);
      const float y1 = xy(1) + (xy(1) < 0 ? -1.0f : 1.0f);
      const float pixel_radius2 = std::sqrt(x1 * x1 + y1 * y1);

      // Distance from camera center to observation on image plane.
      const float pixel_dist1 =
          std::sqrt(pixel_radius1 * pixel_radius1 + focal_length2);
      const float pixel_dist2 =
          std::sqrt(pixel_radius2 * pixel_radius2 + focal_length2);

      // Distance from 3D point to camera center.
      const float dist = (xyz - proj_centers[track_el.image_id]).norm();

      // Perpendicular distance from 3D point to principal axis
      const float r1 = pixel_radius1 * dist / pixel_dist1;
      const float r2 = pixel_radius2 * dist / pixel_dist2;
      const float dr = r2 - r1;

      // Ground resolution of observation, use "minus" to highlight
      // high resolution.
      const float resolution = -dr * dr;

      if (std::isfinite(resolution)) {
        min_resolution = std::min(resolution, min_resolution);
      }
    }

    resolutions.push_back(min_resolution);
    resolutions_[point3D.first] = min_resolution;
  }

  UpdateScale(&resolutions);
}

Eigen::Vector4f PointColormapGroundResolution::ComputeColor(
    const point3D_t point3D_id, const Point3D& point3D) {
  const float gray = AdjustScale(resolutions_[point3D_id]);
  return Eigen::Vector4f(JetColormap::Red(gray), JetColormap::Green(gray),
                         JetColormap::Blue(gray), 1.0f);
}

const Eigen::Vector4f ImageColormapBase::kDefaultPlaneColor = {1.0f, 0.1f, 0.0f,
                                                               0.6f};
const Eigen::Vector4f ImageColormapBase::kDefaultFrameColor = {0.8f, 0.1f, 0.0f,
                                                               1.0f};

ImageColormapBase::ImageColormapBase() {}

void ImageColormapUniform::Prepare(EIGEN_STL_UMAP(camera_t, Camera) & cameras,
                                   EIGEN_STL_UMAP(image_t, Image) & images,
                                   EIGEN_STL_UMAP(point3D_t, Point3D) &
                                       points3D,
                                   std::vector<image_t>& reg_image_ids) {}

void ImageColormapUniform::ComputeColor(const Image& image,
                                        Eigen::Vector4f* plane_color,
                                        Eigen::Vector4f* frame_color) {
  *plane_color = uniform_plane_color;
  *frame_color = uniform_frame_color;
}

void ImageColormapNameFilter::Prepare(EIGEN_STL_UMAP(camera_t, Camera) &
                                          cameras,
                                      EIGEN_STL_UMAP(image_t, Image) & images,
                                      EIGEN_STL_UMAP(point3D_t, Point3D) &
                                          points3D,
                                      std::vector<image_t>& reg_image_ids) {}

void ImageColormapNameFilter::AddColorForWord(
    const std::string& word, const Eigen::Vector4f& plane_color,
    const Eigen::Vector4f& frame_color) {
  image_name_colors_.emplace_back(word,
                                  std::make_pair(plane_color, frame_color));
}

void ImageColormapNameFilter::ComputeColor(const Image& image,
                                           Eigen::Vector4f* plane_color,
                                           Eigen::Vector4f* frame_color) {
  for (const auto& image_name_color : image_name_colors_) {
    if (StringContains(image.Name(), image_name_color.first)) {
      *plane_color = image_name_color.second.first;
      *frame_color = image_name_color.second.second;
      return;
    }
  }

  *plane_color = kDefaultPlaneColor;
  *frame_color = kDefaultFrameColor;
}

}  // namespace colmap