I tried to implement lkdemo's cpp example in iOS, and got reference from [thorrson's lkdemo](https://github.com/manikal/thorrson/blob/master/Thorrson/ViewController.mm). I just use `goodFeaturesToTrack()` to automatically detect features for tracking. All the stuff processed in `processImage:` method based on [iOS documentation](https://docs.opencv.org/2.4/doc/tutorials/ios/video_processing/video_processing.html#opencviosvideoprocessing) but the features are not tracking properly. The first features are detected and appear in cameraview but never tracked, and i try to debug the `calcOpticalFlowPyrLK` but it still working. Is there something wrong? Here's my code on processImage methods:
- (void)processImage:(cv::Mat &)image
{
Mat curntImage, curntGray, prevGray;
cvtColor(image, curntGray, CV_BGR2GRAY);
if (!isDetected) {
goodFeaturesToTrack(curntGray, features[1], maxCorners, qualityLevel, minDistance);
cornerSubPix(curntGray, features[1], subPixWinSize, cv::Size(-1,-1), termcrit);
isDetected = YES;
NSLog(@"Feature detected!");
} else if (!features[0].empty()) {
vector status;
vector err;
if(prevGray.empty()) {
curntGray.copyTo(prevGray);
}
calcOpticalFlowPyrLK(prevGray, curntGray, features[0], features[1], status, err, winSize,
3, termcrit, 0, 0.001);
int radius = 10; // 4, 3, 5, 10
RNG rng(12345);
Scalar color = Scalar(rng.uniform(0,255), rng.uniform(0,255),
rng.uniform(0,255));
size_t i, k;
for (i=k=0; i < features[1].size(); i++) {
if (!status[i])
continue;
features[1][k++] = features[1][i];
circle(image,features[1][i], radius, color, -1, 8); //...-1, 8, 0);
}
features[1].resize(k);
//NSLog(@"Feature tracked on iteration");
}
dispatch_async(dispatch_get_main_queue(), ^{
self.cameraView.image = [UIImage UIImageFromCVMat:image];
});
std::swap(features[0], features[1]);
cv::swap(curntGray, prevGray);
}
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