opencv/samples/c/motempl.c

#include "opencv2/video/tracking_c.h"
#include "opencv2/imgproc/imgproc_c.h"
#include "opencv2/highgui/highgui_c.h"
#include <time.h>
#include <stdio.h>
#include <ctype.h>

static void help(void)
{
    printf(
            "\nThis program demonstrated the use of motion templates -- basically using the gradients\n"
            "of thresholded layers of decaying frame differencing. New movements are stamped on top with floating system\n"
            "time code and motions too old are thresholded away. This is the 'motion history file'. The program reads from the camera of your choice or from\n"
            "a file. Gradients of motion history are used to detect direction of motoin etc\n"
            "Usage :\n"
            "./motempl [camera number 0-n or file name, default is camera 0]\n"
            );
}
// various tracking parameters (in seconds)
const double MHI_DURATION = 1;
const double MAX_TIME_DELTA = 0.5;
const double MIN_TIME_DELTA = 0.05;
// number of cyclic frame buffer used for motion detection
// (should, probably, depend on FPS)
const int N = 4;

// ring image buffer
IplImage **buf = 0;
int last = 0;

// temporary images
IplImage *mhi = 0; // MHI
IplImage *orient = 0; // orientation
IplImage *mask = 0; // valid orientation mask
IplImage *segmask = 0; // motion segmentation map
CvMemStorage* storage = 0; // temporary storage

// parameters:
//  img - input video frame
//  dst - resultant motion picture
//  args - optional parameters
static void  update_mhi( IplImage* img, IplImage* dst, int diff_threshold )
{
    double timestamp = (double)clock()/CLOCKS_PER_SEC; // get current time in seconds
    CvSize size = cvSize(img->width,img->height); // get current frame size
    int i, idx1 = last, idx2;
    IplImage* silh;
    CvSeq* seq;
    CvRect comp_rect;
    double count;
    double angle;
    CvPoint center;
    double magnitude;
    CvScalar color;

    // allocate images at the beginning or
    // reallocate them if the frame size is changed
    if( !mhi || mhi->width != size.width || mhi->height != size.height ) {
        if( buf == 0 ) {
            buf = (IplImage**)malloc(N*sizeof(buf[0]));
            memset( buf, 0, N*sizeof(buf[0]));
        }

        for( i = 0; i < N; i++ ) {
            cvReleaseImage( &buf[i] );
            buf[i] = cvCreateImage( size, IPL_DEPTH_8U, 1 );
            cvZero( buf[i] );
        }
        cvReleaseImage( &mhi );
        cvReleaseImage( &orient );
        cvReleaseImage( &segmask );
        cvReleaseImage( &mask );

        mhi = cvCreateImage( size, IPL_DEPTH_32F, 1 );
        cvZero( mhi ); // clear MHI at the beginning
        orient = cvCreateImage( size, IPL_DEPTH_32F, 1 );
        segmask = cvCreateImage( size, IPL_DEPTH_32F, 1 );
        mask = cvCreateImage( size, IPL_DEPTH_8U, 1 );
    }

    cvCvtColor( img, buf[last], CV_BGR2GRAY ); // convert frame to grayscale

    idx2 = (last + 1) % N; // index of (last - (N-1))th frame
    last = idx2;

    silh = buf[idx2];
    cvAbsDiff( buf[idx1], buf[idx2], silh ); // get difference between frames

    cvThreshold( silh, silh, diff_threshold, 1, CV_THRESH_BINARY ); // and threshold it
    cvUpdateMotionHistory( silh, mhi, timestamp, MHI_DURATION ); // update MHI

    // convert MHI to blue 8u image
    cvCvtScale( mhi, mask, 255./MHI_DURATION,
                (MHI_DURATION - timestamp)*255./MHI_DURATION );
    cvZero( dst );
    cvMerge( mask, 0, 0, 0, dst );

    // calculate motion gradient orientation and valid orientation mask
    cvCalcMotionGradient( mhi, mask, orient, MAX_TIME_DELTA, MIN_TIME_DELTA, 3 );

    if( !storage )
        storage = cvCreateMemStorage(0);
    else
        cvClearMemStorage(storage);

    // segment motion: get sequence of motion components
    // segmask is marked motion components map. It is not used further
    seq = cvSegmentMotion( mhi, segmask, storage, timestamp, MAX_TIME_DELTA );

    // iterate through the motion components,
    // One more iteration (i == -1) corresponds to the whole image (global motion)
    for( i = -1; i < seq->total; i++ ) {

        if( i < 0 ) { // case of the whole image
            comp_rect = cvRect( 0, 0, size.width, size.height );
            color = CV_RGB(255,255,255);
            magnitude = 100;
        }
        else { // i-th motion component
            comp_rect = ((CvConnectedComp*)cvGetSeqElem( seq, i ))->rect;
            if( comp_rect.width + comp_rect.height < 100 ) // reject very small components
                continue;
            color = CV_RGB(255,0,0);
            magnitude = 30;
        }

        // select component ROI
        cvSetImageROI( silh, comp_rect );
        cvSetImageROI( mhi, comp_rect );
        cvSetImageROI( orient, comp_rect );
        cvSetImageROI( mask, comp_rect );

        // calculate orientation
        angle = cvCalcGlobalOrientation( orient, mask, mhi, timestamp, MHI_DURATION);
        angle = 360.0 - angle;  // adjust for images with top-left origin

        count = cvNorm( silh, 0, CV_L1, 0 ); // calculate number of points within silhouette ROI

        cvResetImageROI( mhi );
        cvResetImageROI( orient );
        cvResetImageROI( mask );
        cvResetImageROI( silh );

        // check for the case of little motion
        if( count < comp_rect.width*comp_rect.height * 0.05 )
            continue;

        // draw a clock with arrow indicating the direction
        center = cvPoint( (comp_rect.x + comp_rect.width/2),
                          (comp_rect.y + comp_rect.height/2) );

        cvCircle( dst, center, cvRound(magnitude*1.2), color, 3, CV_AA, 0 );
        cvLine( dst, center, cvPoint( cvRound( center.x + magnitude*cos(angle*CV_PI/180)),
                cvRound( center.y - magnitude*sin(angle*CV_PI/180))), color, 3, CV_AA, 0 );
    }
}


int main(int argc, char** argv)
{
    IplImage* motion = 0;
    CvCapture* capture = 0;

    help();

    if( argc == 1 || (argc == 2 && strlen(argv[1]) == 1 && isdigit(argv[1][0])))
        capture = cvCaptureFromCAM( argc == 2 ? argv[1][0] - '0' : 0 );
    else if( argc == 2 )
        capture = cvCaptureFromFile( argv[1] );

    if( capture )
    {
        cvNamedWindow( "Motion", 1 );

        for(;;)
        {
            IplImage* image = cvQueryFrame( capture );
            if( !image )
                break;

            if( !motion )
            {
                motion = cvCreateImage( cvSize(image->width,image->height), 8, 3 );
                cvZero( motion );
                motion->origin = image->origin;
            }

            update_mhi( image, motion, 30 );
            cvShowImage( "Motion", motion );

            if( cvWaitKey(10) >= 0 )
                break;
        }
        cvReleaseCapture( &capture );
        cvDestroyWindow( "Motion" );
    }

    return 0;
}

#ifdef _EiC
main(1,"motempl.c");
#endif