colmap · ahojnnes · Mar 8, 2021 · Mar 8, 2021
diff --git a/src/base/correspondence_graph.cc b/src/base/correspondence_graph.cc
@@ -191,7 +191,7 @@ CorrespondenceGraph::FindTransitiveCorrespondences(
       const std::vector<Correspondence>& ref_corrs =
           image.corrs[ref_corr.point2D_idx];
 
-      for (const Correspondence corr : ref_corrs) {
+      for (const Correspondence& corr : ref_corrs) {
         // Check if correspondence already collected, otherwise collect.
         auto& corr_image_corrs = image_corrs[corr.image_id];
         if (corr_image_corrs.count(corr.point2D_idx) == 0) {

diff --git a/src/base/reconstruction.cc b/src/base/reconstruction.cc
@@ -1356,7 +1356,7 @@ bool Reconstruction::ExtractColorsForImage(const image_t image_id,
   }
 
   const Eigen::Vector3ub kBlackColor(0, 0, 0);
-  for (const Point2D point2D : image.Points2D()) {
+  for (const Point2D& point2D : image.Points2D()) {
     if (point2D.HasPoint3D()) {
       class Point3D& point3D = Point3D(point2D.Point3DId());
       if (point3D.Color() == kBlackColor) {
@@ -1391,7 +1391,7 @@ void Reconstruction::ExtractColorsForAllImages(const std::string& path) {
       continue;
     }
 
-    for (const Point2D point2D : image.Points2D()) {
+    for (const Point2D& point2D : image.Points2D()) {
       if (point2D.HasPoint3D()) {
         BitmapColor<float> color;
         // COLMAP assumes that the upper left pixel center is (0.5, 0.5).

diff --git a/src/base/undistortion.cc b/src/base/undistortion.cc
@@ -379,7 +379,7 @@ void PMVSUndistorter::WriteVisibilityData() const {
       const Point2D& point2D = image.Point2D(point2D_idx);
       if (point2D.HasPoint3D()) {
         const Point3D& point3D = reconstruction_.Point3D(point2D.Point3DId());
-        for (const TrackElement track_el : point3D.Track().Elements()) {
+        for (const TrackElement& track_el : point3D.Track().Elements()) {
           if (track_el.image_id != image_id) {
             visible_image_ids.insert(track_el.image_id);
           }

diff --git a/src/estimators/utils.cc b/src/estimators/utils.cc
@@ -40,14 +40,14 @@ void CenterAndNormalizeImagePoints(const std::vector<Eigen::Vector2d>& points,
                                    Eigen::Matrix3d* matrix) {
   // Calculate centroid
   Eigen::Vector2d centroid(0, 0);
-  for (const auto point : points) {
+  for (const Eigen::Vector2d& point : points) {
     centroid += point;
   }
   centroid /= points.size();
 
   // Root mean square error to centroid of all points
   double rms_mean_dist = 0;
-  for (const auto point : points) {
+  for (const Eigen::Vector2d& point : points) {
     rms_mean_dist += (point - centroid).squaredNorm();
   }
   rms_mean_dist = std::sqrt(rms_mean_dist / points.size());

diff --git a/src/exe/image.cc b/src/exe/image.cc
@@ -97,7 +97,7 @@ int RunImageDeleter(int argc, char** argv) {
   if (!image_ids_path.empty()) {
     const auto image_ids = ReadTextFileLines(image_ids_path);
 
-    for (const auto image_id_str : image_ids) {
+    for (const auto& image_id_str : image_ids) {
       if (image_id_str.empty()) {
         continue;
       }
@@ -124,7 +124,7 @@ int RunImageDeleter(int argc, char** argv) {
   if (!image_names_path.empty()) {
     const auto image_names = ReadTextFileLines(image_names_path);
 
-    for (const auto image_name : image_names) {
+    for (const auto& image_name : image_names) {
       if (image_name.empty()) {
         continue;
       }

diff --git a/src/exe/model.cc b/src/exe/model.cc
@@ -118,7 +118,7 @@ int RunModelAligner(int argc, char** argv) {
   std::vector<std::string> ref_image_names;
   std::vector<Eigen::Vector3d> ref_locations;
   std::vector<std::string> lines = ReadTextFileLines(ref_images_path);
-  for (const auto line : lines) {
+  for (const auto& line : lines) {
     std::stringstream line_parser(line);
     std::string image_name = "";
     Eigen::Vector3d camera_position;