Merge pull request #26682 from 5usu:4.x

Adding AddRgbFeature(), and improving robustness in ComputeRgbDistance().

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake

modules/gapi/src/3rdparty/vasot/src/components/ot/mtt/objects_associator.cpp

@@ -141,6 +141,12 @@ ObjectsAssociator::ComputeRgbDistance(const std::vector<Detection> &detections,
             if (tracking_per_class_ && (detections[d].class_label != tracklets[t]->label))
                 continue;
 
+             // Check if RGB features are available
+            auto t_rgb_features = tracklets[t]->GetRgbFeatures();
+            if (!t_rgb_features || t_rgb_features->empty()) {
+                continue; // Skip if no RGB features are available
+            }
+
             // Find best match in rgb feature history
             float min_dist = 1000.0f;
             for (const auto &t_rgb_feature : *(tracklets[t]->GetRgbFeatures())) {

modules/gapi/src/3rdparty/vasot/src/components/ot/tracklet.cpp

@@ -7,13 +7,15 @@
 #include "tracklet.hpp"
 
 #include <sstream>
+#include <memory>
 
 namespace vas {
 namespace ot {
 
 Tracklet::Tracklet()
     : id(0), label(-1), association_idx(kNoMatchDetection), status(ST_DEAD), age(0), confidence(0.f),
-      occlusion_ratio(0.f), association_delta_t(0.f), association_fail_count(0) {
+      occlusion_ratio(0.f), association_delta_t(0.f), association_fail_count(0),
+      rgb_features_(std::make_shared<std::deque<cv::Mat>>()) {
 }
 
 Tracklet::~Tracklet() {
@@ -45,12 +47,13 @@ void Tracklet::RenewTrajectory(const cv::Rect2f &bounding_box) {
     trajectory_filtered.push_back(bounding_box);
 }
 
-#define DEFINE_STRING_VAR(var_name, value)                                                                             \
-    std::stringstream __##var_name;                                                                                    \
-    __##var_name << value;                                                                                             \
-    std::string var_name = __##var_name.str();
+std::deque<cv::Mat> *Tracklet::GetRgbFeatures() {
+    return rgb_features_.get(); // Return the raw pointer from the shared_ptr
+}
 
-#define ROUND_F(value, scale) (round((value)*scale) / scale)
+void Tracklet::AddRgbFeature(const cv::Mat &feature) {
+    rgb_features_->push_back(feature);
+}
 
 std::string Tracklet::Serialize() const {
 #ifdef DUMP_OTAV
@@ -97,10 +100,6 @@ std::string Tracklet::Serialize() const {
 #endif
 }
 
-std::deque<cv::Mat> *Tracklet::GetRgbFeatures() {
-    return nullptr;
-}
-
 ZeroTermImagelessTracklet::ZeroTermImagelessTracklet() : Tracklet(), birth_count(1) {
 }
 

modules/gapi/src/3rdparty/vasot/src/components/ot/tracklet.hpp

@@ -13,6 +13,7 @@
 
 #include <cstdint>
 #include <deque>
+#include <memory>
 
 namespace vas {
 namespace ot {
@@ -45,6 +46,7 @@ class Tracklet {
     virtual void RenewTrajectory(const cv::Rect2f &bounding_box);
 
     virtual std::deque<cv::Mat> *GetRgbFeatures();
+    void AddRgbFeature(const cv::Mat &feature);
     virtual std::string Serialize() const; // Returns key:value with comma separated format
 
   public:
@@ -63,6 +65,9 @@ class Tracklet {
     std::deque<cv::Rect2f> trajectory_filtered;
     cv::Rect2f predicted;                      // Result from Kalman prediction. It is for debugging (OTAV)
     mutable std::vector<std::string> otav_msg; // Messages for OTAV
+
+  private:
+    std::shared_ptr<std::deque<cv::Mat>> rgb_features_;
 };
 
 class ZeroTermImagelessTracklet : public Tracklet {