Track Objects (Ultralytics YOLO)

How it fits

Typical backends

Caveats

• Compatibilitydet_model is resolved as an existing path first, then a bare filename looked up in the YOLO cache or downloaded from ultralytics/assets. Restricted networks must pre-seed the cache directory.
• FallbackAn empty ultralytics_assets_release falls back to the rolling latest tag; pin a release tag for reproducibility.
• Fallbackdevice cuda silently falls back to cpu with a warning when no CUDA runtime is visible.
• Parameter interactionChanging det_model, ultralytics_assets_release, tracker, device, iou, img_size, or object_classes triggers a session rebuild (model reload, cache flush, CUDA cache freed); threshold and class_thresholds take effect on the next call without a rebuild.
• State lifetimecpu_threads is read once at module import; runtime updates have no effect.
• State lifetimeTracker memory is in-process (persist=True); restarts drop all ids and every object re-appears with a new track id.
• Hard constraintAn empty object_classes list tracks nothing; the default [0] targets COCO person.
• Hard constrainttracker must be a path to a valid Ultralytics tracker YAML; invalid YAMLs raise inside model.track.