使用javacv opencv使用矩形跟踪移动对象

我目前正在做一个项目的一部分，使用javacv在视频中围绕移动对象创建矩形。我使用了这段代码，当我运行这段代码时，我得到了一个错误，称为this pointer address is null。有人能帮我吗？多谢各位

    while(true) {
        colourImage = cvQueryFrame( capture );

    if( colourImage==null ) break;

    //If this is the first time, initialize the images.
    if(first)
    {
    difference = colourImage.clone();
    temp = colourImage.clone();  

    cvConvertScale(colourImage, movingAverage, 1.0, 0.0);
first = false;
    }       

    //else, make a running average of the motion.
    else
    {

    cvRunningAvg(colourImage, movingAverage, 0.020, null);
    }


    //Convert the scale of the moving average.
    cvConvertScale(movingAverage,temp, 1.0, 0.0);

    //Minus the current frame from the moving average.
    cvAbsDiff(colourImage, temp, difference);


    //Convert the image to grayscale.
    cvCvtColor(difference,greyImage,CV_RGB2GRAY);

    //Convert the image to black and white.
    cvThreshold(greyImage, greyImage, 70, 255, CV_THRESH_BINARY);

    //Dilate and erode to get people blobs
    cvDilate(greyImage, greyImage, null, 18);

    cvErode(greyImage, greyImage, null, 10);


    CvSeq contour=new  CvSeq();
    CvMemStorage storage=CvMemStorage.create();
    cvFindContours(greyImage, storage, contour, Loader.sizeof(CvContour.class), CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE);

    System.out.println(contour.total());

---

你贴的代码有点难读。询问此问题之前是否进行了调试？当未检测到轮廓时，CVFindOnTours之后的contour.isNull可能为真。在这种情况下，contour.total将失败。这是发生错误的地方吗？