Intersection-over-Union (IoU)
Intersection-over-Union (IoU), frequently referred to as the Jaccard Index, is an evaluation metric used to measure the accuracy of an Object Detection algorithm on a particular dataset. In the field of Computer Vision, IoU provides a numerical value that represents the overlap between two Bounding Boxes: the Ground Truth box and the Predicted Bounding Box.
The calculation involves dividing the area of overlap between the predicted box and the ground-truth box by the area of their union. This metric is essential for training models like YOLO (You Only Look Once), Faster R-CNN, and SSD (Single Shot MultiBox Detector). According to research published on arXiv, variations such as Generalized IoU (GIoU) and Distance IoU (DIoU) have been developed to address limitations when boxes do not overlap. Detailed implementation guides can be found at PyImageSearch.
In Machine Learning workflows, a threshold is typically set (e.g., 0.5) to determine if a detection is a True Positive or a False Positive. This classification is fundamental for computing the Mean Average Precision (mAP), a standard benchmark for datasets like the COCO Dataset and Pascal VOC.