opencv/samples/swig_python/motempl.py

#!/usr/bin/python
from opencv.cv import *
from opencv.highgui import *
import sys
import time
from math import cos,sin

CLOCKS_PER_SEC = 1.0
MHI_DURATION = 1
MAX_TIME_DELTA = 0.5
MIN_TIME_DELTA = 0.05
N = 4
buf = range(10) 
last = 0
mhi = None # MHI
orient = None # orientation
mask = None # valid orientation mask
segmask = None # motion segmentation map
storage = None # temporary storage

def update_mhi( img, dst, diff_threshold ):
    global last
    global mhi
    global storage
    global mask
    global orient
    global segmask
    timestamp = time.clock()/CLOCKS_PER_SEC # get current time in seconds
    size = cvSize(img.width,img.height) # get current frame size
    idx1 = last
    if not mhi or mhi.width != size.width or mhi.height != size.height: 
        for i in range( N ):
            buf[i] = cvCreateImage( size, IPL_DEPTH_8U, 1 )
            cvZero( buf[i] )
        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
    cvCvtScale( mhi, mask, 255./MHI_DURATION,
                (MHI_DURATION - timestamp)*255./MHI_DURATION )
    cvZero( dst )
    cvMerge( mask, None, None, None, dst )
    cvCalcMotionGradient( mhi, mask, orient, MAX_TIME_DELTA, MIN_TIME_DELTA, 3 )
    if( not storage ):
        storage = cvCreateMemStorage(0)
    else:
        cvClearMemStorage(storage)
    seq = cvSegmentMotion( mhi, segmask, storage, timestamp, MAX_TIME_DELTA )
    for i in range(-1, seq.total):
        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 = seq[i].rect 
            if( comp_rect.width + comp_rect.height < 100 ): # reject very small components
                continue
            color = CV_RGB(255,0,0)
            magnitude = 30.
        silh_roi = cvGetSubRect(silh, comp_rect)
        mhi_roi = cvGetSubRect( mhi, comp_rect )
        orient_roi = cvGetSubRect( orient, comp_rect )
        mask_roi = cvGetSubRect( mask, comp_rect )
        angle = cvCalcGlobalOrientation( orient_roi, mask_roi, mhi_roi, timestamp, MHI_DURATION)
        angle = 360.0 - angle  # adjust for images with top-left origin
        count = cvNorm( silh_roi, None, CV_L1, None ) # calculate number of points within silhouette ROI
        if( count < comp_rect.width * comp_rect.height * 0.05 ):
            continue
        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 )

if __name__ == "__main__":
    motion = 0
    capture = 0

    if len(sys.argv)==1:
        capture = cvCreateCameraCapture( 0 )
    elif len(sys.argv)==2 and sys.argv[1].isdigit():
        capture = cvCreateCameraCapture( int(sys.argv[1]) )
    elif len(sys.argv)==2:
        capture = cvCreateFileCapture( sys.argv[1] ) 

    if not capture:
        print "Could not initialize capturing..."
        sys.exit(-1)
        
    cvNamedWindow( "Motion", 1 )
    while True:
        image = cvQueryFrame( capture )
        if( image ):
            if( not 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) != -1 ):
                break
        else:
            break
    cvDestroyWindow( "Motion" )