OpenCV: How to use HOGDescriptor::detect method?

Question

I have succeeded in tracking moving objects in a video.

Answer 1

Since you already have a list of objects, you can call the HOGDescriptor::detect method for all objects and check the output foundLocations array. If it is not empty the object was classified as a person. The only thing is that HOG works with 64x128 windows by default, so you need to rescale your objects:

std::vector movingObjects = ...;

cv::HOGDescriptor hog;
hog.setSVMDetector(cv::HOGDescriptor::getDefaultPeopleDetector());
std::vector foundLocations;
for (size_t i = 0; i < movingObjects.size(); ++i)
{
    cv::Mat roi = image(movingObjects[i]);
    cv::Mat window;
    cv::resize(roi, window, cv::Size(64, 128));
    hog.detect(window, foundLocations);
    if (!foundLocations.empty())
    {
        // movingObjects[i] is a person
    }
}