了解OpenCV级联xml文件，以获得情感检测等微笑

Question

我正在尝试使用OpenCV来检测iOS项目上实时视频中的笑脸。我有一些样本，并试图让它工作。我在项目中看到了一个级联的smile.xml文件。当我测试应用程序时，它无法检测到来自摄像机视频的笑脸。我怀疑，这个cascade.xml文件是如何创建的？是否有任何标准的级联xml文件（使用CvHaarClassifierCascade）来检测微笑，悲伤等情绪？

我在这里查看此示例，https://github.com/lukagabric/iOS-OpenCV

- (void)viewDidLoad
{
    NSString *path = [[NSBundle mainBundle] pathForResource:@"smile" ofType:@"xml"];
    _cascade = (CvHaarClassifierCascade*)cvLoad([path cStringUsingEncoding:NSASCIIStringEncoding], NULL, NULL, NULL);
    _storage = cvCreateMemStorage(0);

    [super viewDidLoad];
}

- (void)didCaptureIplImage:(IplImage *)iplImage
{
    IplImage *imgRGB = cvCreateImage(cvGetSize(iplImage), IPL_DEPTH_8U, 3);
    cvCvtColor(iplImage, imgRGB, CV_BGR2RGB);

    IplImage *imgSmall = cvCreateImage(cvSize(imgRGB->width/2, imgRGB->height/2), IPL_DEPTH_8U, 3);
    cvPyrDown(imgRGB, imgSmall, CV_GAUSSIAN_5x5);

    CvSeq *smiles = cvHaarDetectObjects(imgSmall, _cascade, _storage, 1.1f, 3, CV_HAAR_DO_CANNY_PRUNING);

    for (int i = 0; i < smiles->total; i++)
    {
        CvRect cvrect = *(CvRect*)cvGetSeqElem(smiles, 0);

        Mat matImgSmall = Mat(imgSmall);

        rectangle(matImgSmall, cvrect, Scalar(255, 0, 0));
    }

    if (smiles->total > 0)
    {
        [self showSmileWithImage:imgSmall];
    }
    else
    {
        cvReleaseImage(&imgSmall);
    }

    [self didFinishProcessingImage:imgRGB];
}