Use motion detection in analysis of video streams and video files to increase performance (Issue 39)

src/main.cpp

@@ -31,6 +31,7 @@
 #include "support/timing.h"
 #include "support/platform.h"
 #include "video/videobuffer.h"
+#include "video/motiondetector.h"
 #include "alpr.h"
 
 using namespace alpr;
@@ -39,6 +40,8 @@ const std::string MAIN_WINDOW_NAME = "ALPR main window";
 
 const bool SAVE_LAST_VIDEO_STILL = false;
 const std::string LAST_VIDEO_STILL_LOCATION = "/tmp/laststill.jpg";
+MotionDetector motiondetector;
+bool do_motiondetection = true;
 
 /** Function Headers */
 bool detectandshow(Alpr* alpr, cv::Mat frame, std::string region, bool writeJson);
@@ -74,6 +77,7 @@ int main( int argc, const char** argv )
   TCLAP::SwitchArg jsonSwitch("j","json","Output recognition results in JSON format.  Default=off", cmd, false);
   TCLAP::SwitchArg detectRegionSwitch("d","detect_region","Attempt to detect the region of the plate image.  [Experimental]  Default=off", cmd, false);
   TCLAP::SwitchArg clockSwitch("","clock","Measure/print the total time to process image and all plates.  Default=off", cmd, false);
+  TCLAP::SwitchArg motiondetect("", "motion", "Use motion detection on video file or stream.  Default=off", cmd, false);
 
   try
   {
@@ -101,6 +105,7 @@ int main( int argc, const char** argv )
     templatePattern = templatePatternArg.getValue();
     topn = topNArg.getValue();
     measureProcessingTime = clockSwitch.getValue();
+	do_motiondetection = motiondetect.getValue();
   }
   catch (TCLAP::ArgException &e)    // catch any exceptions
   {
@@ -177,12 +182,14 @@ int main( int argc, const char** argv )
       
       if (response != -1)
       {
-        detectandshow( &alpr, latestFrame, "", outputJson);
+		  if (framenum == 0) motiondetector.ResetMotionDetection(&latestFrame);
+		  detectandshow(&alpr, latestFrame, "", outputJson);
       }
       
       // Sleep 10ms
       sleep_ms(10);
-    }
+	  framenum++;
+	}
     
     videoBuffer.disconnect();
     
@@ -206,8 +213,8 @@ int main( int argc, const char** argv )
           cv::imwrite(LAST_VIDEO_STILL_LOCATION, frame);
         }
         std::cout << "Frame: " << framenum << std::endl;
-
-        detectandshow( &alpr, frame, "", outputJson);
+		if (framenum == 0) motiondetector.ResetMotionDetection(&frame);
+		detectandshow(&alpr, frame, "", outputJson);
         //create a 1ms delay
         sleep_ms(1);
         framenum++;
@@ -278,9 +285,14 @@ bool detectandshow( Alpr* alpr, cv::Mat frame, std::string region, bool writeJso
   getTimeMonotonic(&startTime);
 
   std::vector<AlprRegionOfInterest> regionsOfInterest;
-  regionsOfInterest.push_back(AlprRegionOfInterest(0,0, frame.cols, frame.rows));
-  
-  AlprResults results = alpr->recognize(frame.data, frame.elemSize(), frame.cols, frame.rows, regionsOfInterest );
+  if (do_motiondetection)
+  {
+	  cv::Rect rectan = motiondetector.MotionDetect(&frame);
+	  if (rectan.width>0) regionsOfInterest.push_back(AlprRegionOfInterest(rectan.x, rectan.y, rectan.width, rectan.height));
+  }
+  else regionsOfInterest.push_back(AlprRegionOfInterest(0, 0, frame.cols, frame.rows));
+  AlprResults results;
+  if (regionsOfInterest.size()>0) results = alpr->recognize(frame.data, frame.elemSize(), frame.cols, frame.rows, regionsOfInterest);
 
   timespec endTime;
   getTimeMonotonic(&endTime);

src/video/motiondetector.cpp

@@ -0,0 +1,59 @@
+#include "motiondetector.h"
+
+using namespace cv;
+
+MotionDetector::MotionDetector()
+{
+	pMOG2 = cv::createBackgroundSubtractorMOG2();
+}
+
+MotionDetector::~MotionDetector()
+{
+
+}
+
+void MotionDetector::ResetMotionDetection(cv::Mat* frame)
+{
+	pMOG2->apply(*frame, fgMaskMOG2, 1);
+}
+
+cv::Rect MotionDetector::MotionDetect(cv::Mat* frame)
+//Detect motion and create ONE recangle that contains all the detected motion
+{
+	std::vector<std::vector<cv::Point> > contours;
+	std::vector<cv::Vec4i> hierarchy;
+	cv::Rect bounding_rect;
+	std::vector<cv::Rect> rects;
+	cv::Rect largest_rect, rect_temp;
+
+	// Detect motion
+	pMOG2->apply(*frame, fgMaskMOG2, -1);
+	//Remove noise
+	cv::erode(fgMaskMOG2, fgMaskMOG2, getStructuringElement(cv::MORPH_RECT, cv::Size(6, 6)));
+	// Find the contours of motion areas in the image
+	findContours(fgMaskMOG2, contours, hierarchy, CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE);
+	// Find the bounding rectangles of the areas of motion
+	if (contours.size() > 0)
+	{
+		for (int i = 0; i < contours.size(); i++)
+		{
+			bounding_rect = boundingRect(contours[i]);
+			rects.push_back(bounding_rect);
+		}
+		// Determine the overall area with motion.
+		largest_rect = rects[0];
+		for (int i = 1; i < rects.size(); i++)
+		{
+			rect_temp.x = min(largest_rect.x,rects[i].x);
+			rect_temp.y = min(largest_rect.y,rects[i].y);
+			rect_temp.width = max(largest_rect.x + largest_rect.width, rects[i].x + rects[i].width)-rect_temp.x;
+			rect_temp.height = max(largest_rect.y + largest_rect.height, rects[i].y + rects[i].height) - rect_temp.y;
+			largest_rect = rect_temp;
+		}
+		rectangle(*frame, rect_temp, cv::Scalar(0, 255, 0), 1, 8, 0);
+	}
+	else
+		largest_rect = { 0, 0, 0, 0 };
+//	imshow("Motion detect", fgMaskMOG2);
+	return largest_rect;
+}

src/video/motiondetector.h

@@ -0,0 +1,13 @@
+#include "opencv2/opencv.hpp"
+
+class MotionDetector
+{
+	private: cv::Ptr<cv::BackgroundSubtractor> pMOG2; //MOG2 Background subtractor
+	private: cv::Mat fgMaskMOG2;
+	public:
+		MotionDetector();
+		virtual ~MotionDetector();
+
+		void ResetMotionDetection(cv::Mat* frame);
+		cv::Rect MotionDetect(cv::Mat* frame);
+};