syntax for particle filter in opencv 2.4.3

code.opencv

asked 2013-02-06 05:01:48 -0600

neerat.sharma
30 ●1 ●2 ●6

or any other solution... is particle filter have any connection with blob tracking. ...... in opencv 2.1 used particle filter used as Cvcondensation but in 2.4.3 no such function for particle filter.........

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answered 2013-03-11 03:33:10 -0600

theodore

4133 ●12 ●41 ●101

First, thanks for the nice example, it is really helpful.

Second, a question in order to include velocity the following modification, is enough:

int dim = 4; // including velocity
...
...
// including velocity
float minRange[] = { 0, 0, -1.0, -1.0 };
float maxRange[] = { xRange, yRange, 1.0, 1.0 };
CvMat LB, UB;
cvInitMatHeader(&LB, 4, 1, CV_32FC1, minRange);
cvInitMatHeader(&UB, 4, 1, CV_32FC1, maxRange);
...
...
// including velocity
condens->DynamMatr[0] = 1.0;
condens->DynamMatr[1] = 0.0;
condens->DynamMatr[2] = 1.0;
condens->DynamMatr[3] = 0.0;

condens->DynamMatr[4] = 0.0;
condens->DynamMatr[5] = 1.0;
condens->DynamMatr[6] = 0.0;
condens->DynamMatr[7] = 1.0;

condens->DynamMatr[8] = 0.0;
condens->DynamMatr[9] = 0.0;
condens->DynamMatr[10] = 1.0;
condens->DynamMatr[11] = 0.0;

condens->DynamMatr[12] = 0.0;
condens->DynamMatr[13] = 0.0;
condens->DynamMatr[14] = 0.0;
condens->DynamMatr[15] = 1.0;

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answered 2013-02-21 17:59:52 -0600

Tom Sgouros
51 ●1 ●4

The cvConDensation code had some bugs in its resampling stage and did not work very well. (Neither did the example in the OpenCV book.) Here is an example that works. Note that the DynamMatr matrix is not automatically initialized, so you have to do that yourself.

// Example of how to use the OpenCV Particle Filter.
// 
// Stolen largely from morethantechnical.com's nice mouse_kalman project.
//

#include <iostream>
#include <vector>

#include <opencv2/opencv.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/video/tracking.hpp>
#include <opencv2/legacy/legacy.hpp>

using namespace std;

#define drawCross( center, color, d )                  \
  line( img, cv::Point( center.x - d, center.y - d ),           \
    cv::Point( center.x + d, center.y + d ), color, 2, CV_AA, 0);   \
  line( img, cv::Point( center.x + d, center.y - d ),           \
    cv::Point( center.x - d, center.y + d ), color, 2, CV_AA, 0 )

struct mouse_info_struct { int x,y; };
struct mouse_info_struct mouse_info = {-1,-1}, last_mouse;

vector<cv::Point> mouseV, particleV;
int counter = -1;

// Define this to proceed one click at a time.
//#define CLICK 1
#define PLOT_PARTICLES 1

void on_mouse(int event, int x, int y, int flags, void* param) {
#ifdef CLICK
  if (event == CV_EVENT_LBUTTONUP) 
#endif
  {
    last_mouse = mouse_info;
    mouse_info.x = x;
    mouse_info.y = y;
    counter = 0;
  }
}

int main (int argc, char * const argv[]) {
  cv::Mat img(650, 650, CV_8UC3);
  char code = (char)-1;

  cv::namedWindow("mouse particle");
  cv::setMouseCallback("mouse particle", on_mouse, 0);

  cv::Mat_<float> measurement(2,1); 
  measurement.setTo(cv::Scalar(0));

  int dim = 2;
  int nParticles = 25;
  float xRange = 650.0;
  float yRange = 650.0;

  float minRange[] = { 0, 0 };
  float maxRange[] = { xRange, yRange };
  CvMat LB, UB;
  cvInitMatHeader(&LB, 2, 1, CV_32FC1, minRange);
  cvInitMatHeader(&UB, 2, 1, CV_32FC1, maxRange);

  CvConDensation* condens = cvCreateConDensation(dim, dim, nParticles);

  cvConDensInitSampleSet(condens, &LB, &UB);

  // The OpenCV documentation doesn't tell you to initialize this
  // transition matrix, but you have to do it.  For this 2D example, 
  // we're just using a 2x2 identity matrix.  I'm sure there's a slicker 
  // way to do this, left as an exercise for the reader.
  condens->DynamMatr[0] = 1.0;
  condens->DynamMatr[1] = 0.0;
  condens->DynamMatr[2] = 0.0;
  condens->DynamMatr[3] = 1.0;

  for(;;) {

    if (mouse_info.x < 0 || mouse_info.y < 0) {
      imshow("mouse particle", img);
      cv::waitKey(30);
      continue;
    }

    mouseV.clear();
    particleV.clear();

    for(;;) {
      code = (char)cv::waitKey(100);

      if( code > 0 )
    break;

#ifdef CLICK
      if (counter++ > 0) {
    continue;
      } 
#endif

      measurement(0) = mouse_info.x;
      measurement(1) = mouse_info.y;

      cv::Point measPt(measurement(0),measurement(1));
      mouseV.push_back(measPt);

      // Clear screen
      img = cv::Scalar::all(100);

      for (int i = 0; i < condens->SamplesNum; i++) {

    float diffX = (measurement(0) - condens->flSamples[i][0])/xRange;
    float diffY = (measurement(1) - condens->flSamples[i][1])/yRange;

    condens->flConfidence[i] = 1.0 / (sqrt(diffX * diffX + diffY * diffY));

    // plot particles
#ifdef PLOT_PARTICLES
    cv::Point partPt(condens->flSamples[i][0], condens->flSamples[i][1]);
    drawCross(partPt , cv::Scalar(255,0,255), 2);
#endif

      }

      cvConDensUpdateByTime(condens);

      cv::Point statePt(condens->State[0], condens->State[1]);
      particleV.push_back(statePt);

      // plot points
      drawCross( statePt, cv::Scalar(255,255,255), 5 ...

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