Fix issue that generate two or more objects with the same LP numbers/user name in the same image frame

modules/ANSLPR/ANSLPR_OD.cpp

@@ -990,6 +990,10 @@ namespace ANSCENTER {
 		cv::waitKey(1);
 #endif
 
+		// Deduplicate: if two trackIds claim the same plate text, keep the one
+		// with the higher accumulated score to prevent plate flickering
+		ensureUniquePlateText(output, cameraId);
+
 		return output;
 
 		}
@@ -2313,6 +2317,10 @@ namespace ANSCENTER {
 				output.push_back(std::move(lprObject));
 			}
 
+			// Deduplicate: if two trackIds claim the same plate text, keep the one
+			// with the higher accumulated score to prevent plate flickering
+			ensureUniquePlateText(output, cameraId);
+
 			return output;
 		}
 		catch (const cv::Exception& e) {
@@ -2701,4 +2709,102 @@ namespace ANSCENTER {
 			return AnalyseLicensePlateText(ocrText);
 		}
 	}
+
+	void ANSALPR_OD::ensureUniquePlateText(std::vector<Object>& results, const std::string& cameraId)
+	{
+		if (results.empty()) return;
+
+		auto isEmptyPlate = [](const std::string& plate) {
+			return plate.empty();
+		};
+
+		auto& identities = _plateIdentities[cameraId];
+
+		// Step 1: Build map of plateText → candidate indices
+		std::unordered_map<std::string, std::vector<size_t>> plateCandidates;
+		for (size_t i = 0; i < results.size(); ++i) {
+			if (isEmptyPlate(results[i].className)) continue;
+			plateCandidates[results[i].className].push_back(i);
+		}
+
+		// Step 2: Resolve duplicates using accumulated scores
+		for (auto& [plateText, indices] : plateCandidates) {
+			if (indices.size() <= 1) continue;
+
+			// Find the candidate with the highest accumulated score
+			size_t winner = indices[0];
+			float bestScore = 0.0f;
+
+			for (size_t idx : indices) {
+				int tid = results[idx].trackId;
+				float score = results[idx].confidence; // fallback for new trackIds
+				auto it = identities.find(tid);
+				if (it != identities.end() && it->second.plateText == plateText) {
+					score = it->second.accumulatedScore + results[idx].confidence;
+				}
+				if (score > bestScore) {
+					bestScore = score;
+					winner = idx;
+				}
+			}
+
+			// Clear plate text from non-winners
+			for (size_t idx : indices) {
+				if (idx != winner) {
+					results[idx].className.clear();
+				}
+			}
+		}
+
+		// Step 3: Update accumulated scores — winners accumulate, losers decay
+		constexpr float DECAY_FACTOR = 0.8f;
+		constexpr float MIN_SCORE = 0.1f;
+
+		for (auto& r : results) {
+			int tid = r.trackId;
+
+			if (isEmptyPlate(r.className)) {
+				// Lost dedup or empty — decay
+				auto it = identities.find(tid);
+				if (it != identities.end()) {
+					it->second.accumulatedScore *= DECAY_FACTOR;
+					if (it->second.accumulatedScore < MIN_SCORE) {
+						identities.erase(it);
+					}
+				}
+				continue;
+			}
+
+			auto it = identities.find(tid);
+			if (it != identities.end()) {
+				if (it->second.plateText == r.className) {
+					it->second.accumulatedScore += r.confidence;
+				} else {
+					it->second.plateText = r.className;
+					it->second.accumulatedScore = r.confidence;
+				}
+			} else {
+				identities[tid] = { r.className, r.confidence };
+			}
+		}
+
+		// Step 4: Clean up trackIds no longer in the scene
+		std::unordered_set<int> activeTrackIds;
+		for (const auto& r : results) {
+			activeTrackIds.insert(r.trackId);
+		}
+		for (auto it = identities.begin(); it != identities.end(); ) {
+			if (activeTrackIds.find(it->first) == activeTrackIds.end()) {
+				it = identities.erase(it);
+			} else {
+				++it;
+			}
+		}
+
+		// Step 5: Remove entries with cleared plate text from results
+		results.erase(
+			std::remove_if(results.begin(), results.end(),
+				[](const Object& o) { return o.className.empty(); }),
+			results.end());
+	}
 };