LiDAR Topics
The lidar topics are managed by the lidarpub service and handles interfacing with a connected lidar to produce lidar point clouds, reflectivity maps, and depth maps.
- Ouster OS1
The lidar topics are published under the /lidar namespace and offers the following sub-topics: /lidar/points, /lidar/reflect, /lidar/depth, and /lidar/clusters. The density of the lidar points, the frequency of updates, and the field of view of the lidar are configurable through the lidarpub service. See lidarpub service configuration documentation for details.
/lidar/points
The /lidar/points topic publishes information about the lidar points using the PointCloud2 schema. The point cloud will have the fields x, y, z, and reflect.
| Field Name | Datatype | Units | Notes |
|---|---|---|---|
| x | float32 | m | Represent XYZ location of the point |
| y | float32 | m | Represent XYZ location of the point |
| z | float32 | m | Represent XYZ location of the point |
| reflect | uint8 | Intensity of reflected LiDAR beam |
The XYZ coordinate system follows the standard ROS convention of x forward, y left, z up. However, note that the lidar frame is rotated 180 degrees from the base_link frame, with forward facing the back of the camera.
| Usage | Link |
|---|---|
| WebUI | |
| Foxglove | PointCloud2 Example |
| SDK | Lidar Points Example |
/lidar/reflect
The /lidar/reflect topic publishes the reflectivity map using the Image schema. The encoding of the image is mono8. The value of a pixel is the reflectivity of that point. The width of a pixel depends on the number of columns configured on the lidar.
| Usage | Link |
|---|---|
| WebUI | |
| Foxglove | Image Example |
| SDK | Lidar Reflect Example |
/lidar/depth
The /lidar/depth topic publishes the depth map using the Image schema. The encoding of the image is mono16. The value of a pixel is the distance from the lidar to the point in millimeters. The width of a pixel depends on the number of columns configured on the lidar.
| Usage | Link |
|---|---|
| WebUI | |
| Foxglove | Image Example |
| SDK | Lidar Depth Example |
/lidar/clusters
The /lidar/clusters topic publishes the lidar clusters pointcloud using the PointCloud2 schema. The point cloud will have the fields x, y, z, cluster_id, and reflect.
| Field Name | Datatype | Units | Notes |
|---|---|---|---|
| x | float32 | m | Represent XYZ location of the point |
| y | float32 | m | Represent XYZ location of the point |
| z | float32 | m | Represent XYZ location of the point |
| cluster_id | uint32 | 0 means not clustered. Otherwise same cluster id means same cluster | |
| reflect | uint8 | Intensity of reflected LiDAR beam |
The XYZ coordinate system follows the standard ROS convention of x forward, y left, z up. However, note that the lidar frame is rotated 180 degrees from the base_link frame, with forward facing the back of the camera.
This topic is only published if the lidarpub service is configured with the clustering task enabled.
| Usage | Link |
|---|---|
| WebUI | |
| Foxglove | PointCloud2 Example |
| SDK | Lidar Clusters Example |