Removed useless parameters in processor yaml, added a lot of comments in the yaml

demos/processor_visual_odometry.yaml

-# ProcessorBase and ProcessorTracker    parameters
 time_tolerance: 0.005
 
 keyframe_vote:
     voting_active: true
-    min_features_for_keyframe: 42  # not used
+    # Trigger a new keyframe creation as well as detection of new keypoints in last frame
+    # when the track number goes below min_features_for_keyframe in incoming
+    min_features_for_keyframe: 10
 
+# Use a robust cost function
 apply_loss_function: true
 
-# ProcessorTracker
-max_new_features: 42  # not used
+# Select the best new Keypoints when performing detection
+max_new_features: 100
 
-# ProcessorBase parameters
+####################################
+# ProcessorVisualOdometry parameters
+# FAST KeyPoint detection 
+fast_params:
+    # Threshold on the keypoint pixel intensity (in uchar [0-255]) 
+    # the higher, the more selective the detector is
+    threshold_fast: 50
+    # Avoids getting multiple keypoints at the same place
+    non_max_suppresion: true
+
+# Lucas Kanade tracking parameters
 klt_params:
     patch_width: 15
     patch_height: 15
     nlevels_pyramids: 3
     klt_max_err: 0.3
 
-fast_params:
-    threshold_fast: 50
-    non_max_suppresion: true
-
-min_nb_tracks: 10
+# Keep the number of tracks below 
 max_nb_tracks: 20
 
+# standard deviation of the pixel reprojection factor 
 std_pix: 1
 
+# before creating a landmark, wait until the track is old enough
 min_track_length_for_landmark: 3
-
-max_new_detections: 100

include/vision/processor/processor_visual_odometry.h

@@ -71,8 +71,6 @@ struct ParamsProcessorVisualOdometry : public ParamsProcessorTracker
     double std_pix_;
     KltParams klt_params_;
     FastParams fast_params_;
-    unsigned int max_new_detections_;
-    unsigned int min_nb_tracks_;
     unsigned int max_nb_tracks_;
     unsigned int min_track_length_for_landmark_;
 
@@ -91,8 +89,6 @@ struct ParamsProcessorVisualOdometry : public ParamsProcessorTracker
         fast_params_.threshold_fast_     = _server.getParam<int>( prefix + _unique_name + "/fast_params/threshold_fast");
         fast_params_.non_max_suppresion_ = _server.getParam<bool>(prefix + _unique_name + "/fast_params/non_max_suppresion");
 
-        max_new_detections_ = _server.getParam<unsigned int>(prefix + _unique_name + "/max_new_detections");
-        min_nb_tracks_ = _server.getParam<unsigned int>(prefix + _unique_name + "/min_nb_tracks");
         max_nb_tracks_ = _server.getParam<unsigned int>(prefix + _unique_name + "/max_nb_tracks");
         min_track_length_for_landmark_ = _server.getParam<unsigned int>(prefix + _unique_name + "/min_track_length_for_landmark");
 
@@ -106,7 +102,6 @@ struct ParamsProcessorVisualOdometry : public ParamsProcessorTracker
             + "klt_params_.nlevels_pyramids_: "    + std::to_string(klt_params_.nlevels_pyramids_)     + "\n"
             + "fast_params_.threshold_fast_    : " + std::to_string(fast_params_.threshold_fast_)      + "\n"
             + "fast_params_.non_max_suppresion_: " + std::to_string(fast_params_.non_max_suppresion_)  + "\n"
-            + "min_nb_tracks_: "                   + std::to_string(min_nb_tracks_)                    + "\n"  
             + "max_nb_tracks_: "                   + std::to_string(max_nb_tracks_)                    + "\n"
             + "min_track_length_for_landmark_: "   + std::to_string(min_track_length_for_landmark_)    + "\n";
     }

src/processor/processor_visual_odometry.cpp

@@ -86,7 +86,7 @@ void ProcessorVisualOdometry::preProcess()
         detector_->detect(img_incoming, kps_current);
 
         // Select a limited number of these keypoints
-        cv::KeyPointsFilter::retainBest(kps_current, params_visual_odometry_->max_new_detections_);
+        cv::KeyPointsFilter::retainBest(kps_current, params_visual_odometry_->max_new_features);
         capture_image_incoming_->addKeyPoints(kps_current);
 
         // Initialize the tracks data structure with a "dummy track" where the keypoint is pointing to itself
@@ -157,13 +157,13 @@ void ProcessorVisualOdometry::preProcess()
     // detect new KeyPoints in last and track them to incoming
     ////////////////////////////////
     size_t n_tracks_origin = tracks_origin_incoming.size();
-    if (n_tracks_origin < params_visual_odometry_->min_nb_tracks_){
+    if (n_tracks_origin < params_visual_odometry_->min_features_for_keyframe){
         std::cout << "  Too Few Tracks" << std::endl;
 
         // Detect new KeyPoints 
         std::vector<cv::KeyPoint> kps_last_new;
         detector_->detect(img_last, kps_last_new);
-        cv::KeyPointsFilter::retainBest(kps_last_new, params_visual_odometry_->max_new_detections_);
+        cv::KeyPointsFilter::retainBest(kps_last_new, params_visual_odometry_->max_new_features);
         
         // Create a map of wolf KeyPoints to track only the new ones
         KeyPointsMap mwkps_last_new, mwkps_incoming_new;
@@ -181,6 +181,8 @@ void ProcessorVisualOdometry::preProcess()
 
         // Concatenation of old tracks and new tracks
         // Only keep tracks until it reaches a max nb of tracks
+        // TODO: the strategy for keeping the best new tracks is dumb
+        //    -> should be improved for a better spatial repartition
         unsigned int count_new_tracks = 0;
         for (auto & track: tracks_last_incoming_new){
             if ((n_tracks_origin + count_new_tracks) >= params_visual_odometry_->max_nb_tracks_){

test/gtest_processor_visual_odometry.cpp

@@ -147,7 +147,7 @@ TEST(ProcessorVisualOdometry, preProcess)
     params->klt_params_.criteria_ = cv::TermCriteria(cv::TermCriteria::COUNT+cv::TermCriteria::EPS, 30, 0.01);
     params->fast_params_.threshold_fast_ = 20;
     params->fast_params_.non_max_suppresion_ = true;
-    params->min_nb_tracks_ = 50;
+    params->min_features_for_keyframe = 50;
     params->max_nb_tracks_ = 400;
     params->min_track_length_for_landmark_ = 4;
     ProcessorVisualOdometryTest processor(params);

test/processor_visual_odometry_gtest.yaml

-# ProcessorBase and ProcessorTracker    parameters
 time_tolerance: 0.005
 
 keyframe_vote:
     voting_active: true
-    min_features_for_keyframe: 42  # not used
+    # Trigger a new keyframe creation as well as detection of new keypoints in last frame
+    # when the track number goes below min_features_for_keyframe in incoming
+    min_features_for_keyframe: 10
 
+# Use a robust cost function
 apply_loss_function: true
 
-# ProcessorTracker
-max_new_features: 42  # not used
+# Select the best new Keypoints when performing detection
+max_new_features: 100
 
-# ProcessorBase parameters
+####################################
+# ProcessorVisualOdometry parameters
+# FAST KeyPoint detection 
+fast_params:
+    # Threshold on the keypoint pixel intensity (in uchar [0-255]) 
+    # the higher, the more selective the detector is
+    threshold_fast: 50
+    # Avoids getting multiple keypoints at the same place
+    non_max_suppresion: true
+
+# Lucas Kanade tracking parameters
 klt_params:
     patch_width: 15
     patch_height: 15
     nlevels_pyramids: 3
     klt_max_err: 0.3
 
-fast_params:
-    threshold_fast: 50
-    non_max_suppresion: true
-
-min_nb_tracks: 100
-max_nb_tracks: 200
+# Keep the number of tracks below 
+max_nb_tracks: 20
 
+# standard deviation of the pixel reprojection factor 
 std_pix: 1
 
+# before creating a landmark, wait until the track is old enough
 min_track_length_for_landmark: 3
-
-max_new_detections: 100