> For clean Markdown of any page, append .md to the page URL. > For a complete documentation index, see https://docs.stereolabs.com/llms.txt. > For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.stereolabs.com/_mcp/server. # Body Tracking with ROS 2 The ROS 2 wrapper offers full support for the Body Tracking module of the ZED SDK. The Body Tracking module can be [configured](/docs/integrations/ros-2/zed-stereo-node/#body-tracking-parameters) to use one of the available detection models: | MODEL | Description | | --------------------- | --------------------------------------------------------------------------------------------------------------- | | `HUMAN_BODY_FAST` | Keypoints based, specific to human skeleton, real time performance even on NVIDIA® Jetson™ or low-end GPU cards | | `HUMAN_BODY_MEDIUM` | Keypoints based, specific to human skeleton, compromise between accuracy and speed | | `HUMAN_BODY_ACCURATE` | Keypoints based, specific to human skeleton, state of the art accuracy, requires powerful GPU | The Body Tracking module can be [configured](/docs/integrations/ros-2/zed-stereo-node/#body-tracking-parameters) to use one of the available body formats: | FORMAT | Description | | --------- | --------------------------------------------------------------------------- | | `BODY_18` | 18 keypoints model. Basic Body model | | `BODY_34` | 34 keypoints model (**default**). Body model, requires body fitting enabled | | `BODY_38` | 38 keypoints model. Body model, including feet, simplified face, and hands | Starting from ZED SDK 5.5 the module can also be [configured](/docs/integrations/ros-2/zed-stereo-node/#body-tracking-parameters) to select the network generation with the `body_tracking.model_gen` parameter: | GENERATION | Description | | ---------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `GEN_1` | The network used up to ZED SDK 5.4 | | `GEN_2` | **Default**. Bottom-up network: more robust in crowded scenes and to unusual body orientations, detects people further from the camera, and is up to 18% faster and 14% more accurate than `GEN_1`. It always runs in FP16, so `body_tracking.allow_reduced_precision_inference` has no effect on it | > **Note** > > Only `BODY_18` and `BODY_34` have a `GEN_2` network: with `BODY_38` the ZED SDK falls back to `GEN_1`. > > Since v5.5.0 of the ROS 2 Wrapper the default body format is `BODY_34` instead of `BODY_38`, and `body_tracking.enable_body_fitting` defaults to `true`, so that the default configuration actually runs `GEN_2`. Skeletons published on `~/body_trk/skeletons` now carry 34 keypoints instead of 38: set `body_format` back to `BODY_38` to keep the previous topology, at the cost of running `GEN_1`. The result of the detection is published using a custom message of type [zed\_msgs/ObjectsStamped](/docs/integrations/ros-2/custom-msgs/#object-detection-and-body-tracking-results) defined in the package [zed\_msgs](https://github.com/stereolabs/zed-ros2-interfaces). ## Enable Body Tracking Body Tracking can be started automatically when the ZED Wrapper node starts by setting the parameter `body_tracking.bt_enabled` to `true` in the file `common_stereo.yaml`. It is also possible to start the Body Tracking processing manually by calling the service `~/enable_body_trk` with the parameter `True`. In both cases, the Body Tracking processing can be stopped by calling the service `~/enable_body_trk` with the parameter `False`. See the [services](/docs/integrations/ros-2/zed-stereo-node/#services) documentation for more info. ## Body Tracking results in RViz 2 To visualize the results of the Body Tracking processing in RViz 2, the `ZedOdDisplay` plugin is required. The plugin is available in the [zed-ros2-examples](https://github.com/stereolabs/zed-ros2-examples) GitHub repository and can be installed following the [online instructions](https://github.com/stereolabs/zed-ros2-examples#build-the-package). > **Note** > > [The source code of the plugin](https://github.com/stereolabs/zed-ros2-examples/tree/master/rviz-plugin-zed-od) is a valid example of how to process the data of the topics of type [zed\_msgs/ObjectsStamped](/docs/integrations/ros-2/custom-msgs/#object-detection-and-body-tracking-results). ![image](/_fern-img/bb95433a7b36e2430e5913e9e2cdbda0bf79832ed6159537a248441734aeacda.webp) Parameters: * `Topic`: Selects the body tracking topic to visualize from the list of available topics in the combo box. * `Depth`: The depth of the incoming message queue. * `History policy`: Set the QoS history policy. `Keep Last` is suggested for performance and compatibility. * `Reliability Policy`: Set the QoS reliability policy. `Best Effort` is suggested for performance and compatibility. * `Durability Policy`: Set the QoS durability policy. `Volatile` is suggested for compatibility. * `Transparency`: the transparency level of the structures composing the detected bodies. * `Show skeleton`: enable/disable the visualization of the skeleton of the detected persons. * `Show Labels`: enable/disable the visualization of the label. * `Show Bounding Boxes`: enable/disable the visualization of the bounding boxes of the detected bodies. * `Link Size`: the size of the bounding boxes' corner lines and skeleton link lines. * `Joint Radius`: the radius of the spheres placed on the corners of the bounding boxes and on the skeleton joint points. * `Label Scale`: the scale of the label of the bodies. ![image](https://cdn.sanity.io/images/s18ewfw4/production/31b4c39404ab1c3c499bebbafc3b1b917cbab2a3-1877x1055.webp)