Method group

openbr/core/opencvutils.cpp:439–542

TODO: Make sure case where no confidences are inputted works.

// TODO: Make sure case where no confidences are inputted works.
void OpenCVUtils::group(QList<Rect> &rects, QList<float> &confidences, float confidenceThreshold, float epsilon)
{
    if (rects.isEmpty())
        return;

    const bool useConfidences = !confidences.isEmpty();

    vector<int> labels;
    int nClasses = cv::partition(rects.toVector().toStdVector(), labels, SimilarRects(epsilon));

    // Rect for each class (class meaning identity assigned by partition)
    vector<Rect> rrects(nClasses);

    // Total number of rects in each class
    vector<int> rweights(nClasses, 0);
    vector<float> rejectWeights(nClasses, -std::numeric_limits<float>::max());

    for (size_t i = 0; i < labels.size(); i++)
    {
        int cls = labels[i];
        rrects[cls].x += rects[i].x;
        rrects[cls].y += rects[i].y;
        rrects[cls].width += rects[i].width;
        rrects[cls].height += rects[i].height;
        rweights[cls]++;
    }

    if (useConfidences)
    {
        // For each class, find maximum confidence
        for (size_t i = 0; i < labels.size(); i++)
        {
            int cls = labels[i];
            if (confidences[i] > rejectWeights[cls])
                rejectWeights[cls] = confidences[i];
        }
    }

    // Find average rectangle for all classes
    for (int i = 0; i < nClasses; i++)
    {
        Rect r = rrects[i];
        float s = 1.f/rweights[i];
        rrects[i] = Rect(saturate_cast<int>(r.x*s),
             saturate_cast<int>(r.y*s),
             saturate_cast<int>(r.width*s),
             saturate_cast<int>(r.height*s));
    }

    rects.clear();
    confidences.clear();

    // Aggregate by comparing average rectangles against other average rectangels
    for (int i = 0; i < nClasses; i++)
    {
        // Average rectangle
        Rect r1 = rrects[i];