Object detection and segmentation#

The detection step consists in finding objects of interest in an input frame/video. In general, the detection is characterized by a bounding rectangular box.

Some detectors, like YOLOv8, can furthermore segment the detection (i.e., find the mask of pixels corresponding to each object of interest). Such masks are exported using polylines to get smaller and more comprehensive JSON output files.

Foreground extraction#

The arena-foreground application updates frame-by-frame a background model. Then, for each frame, it compares the background model and the current frame by applying a background subtraction to deduce players’ contours.

arena-foreground -i remap/remap_north_front.mp4 -o output/foreground_north_front.mp4

YOLO#

The arena-yolo-tracking application detects humans using YOLO (You Only Look Once) appearing in an output video (-i). The detections are showed in the played video, which may be saved to an output file (-o)

Currently, only YOLOv3 and YOLOv8 are supported (--yolo-version). By default, YOLOv3 is used.

  • You must choose YOLOv3 if the running machine has no GPU, as YOLOv8 requires a GPU.

  • Both YOLOv3 and YOLOv8 output detection boxes.

  • If you need detection masks (segmentation), use YOLOv8.

Once the video is processed, the results can be dumped to an output file (-j).

  • YOLOv3:

arena-yolo-tracking -i remap/remap_north_front.mp4 -o output/yolov3_north_front.mp4
arena-yolo-tracking -i remap/remap_north_front.mp4 -o output/yolov3_north_front.mp4 --yolo-version 3 -j json/yolov3/remap_north_front.json

  • YOLOv8: ensure your machine has a GPU

arena-yolo-tracking -i remap/remap_north_front.mp4 -o output/yolov8_north_front.mp4 --yolo-version 8 -j json/yolov8/remap_north_front.json

Many other options are available, see arena-yolo-tracking --help for further details.

HOG#

The arena-hog-tracking application detects humans using HOG (Histogram of Oriented Gradients) and NMS (Non-Max Suppression).

arena-hog-tracking -i remap/remap_north_front.mp4 -o output/hog_north_front.mp4

MOG#

The arena-mog-tracking application detects humans using MOG (Mixture Of Gaussians).

arena-mog-tracking -i remap/remap_north_front.mp4 -o output/mog_north_front.mp4