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url: /detection/motion.md
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# Motion detection

Motion is the first and cheapest layer of [detection](/detection/). It watches for change in the frame and, when it sees movement, wakes the heavier AI. On its own it can also trigger recordings and notifications.

## Choosing a motion engine

camera.ui offers several motion plugins. Enable one for a camera in its [settings](/cameras/settings) under the Plugins tab (see [Set up sensors](/sensors/setup)):

* **Rust Motion.** Fast and efficient; a good default for most setups.
* **OpenCV.** Several algorithms with fine-grained tuning.
* **OpenCL.** GPU-accelerated, for very low CPU use.
* **WASM Motion.** Cross-platform WebAssembly.
* **Pam Diff.** Lightweight pixel-difference.
* **SMTP.** For cameras that send motion alerts by email instead of analysing the video.

## Tuning sensitivity

Each engine exposes its own settings (such as area, threshold, and blur) in its plugin settings, with a reset to defaults. Two settings live on the camera itself, in [Settings → Detection](/cameras/settings):

* **Motion resolution.** Low is fastest, medium is balanced, high is most accurate.
* **Motion timeout.** How long motion stays "active" after movement stops (minimum 10 seconds).

If a camera is too sensitive (a busy road, a swaying tree), limit where motion counts with [zones](/cameras/zones-and-masks).

A camera's on-screen timestamp can trigger motion too, mostly at night and at higher motion resolutions. Motion events with nothing in frame are the sign: draw a motion zone that leaves out the timestamp corner.

## The cascade

When motion fires, it triggers the heavier detectors (object, face, and so on). You can also let other sensors start this cascade, for example a door contact sensor triggering object detection, under **Sensor triggers** in the camera's detection settings.