Laser Scan
PROClose-range obstacle view: robot-centered lidar points with distance gradient and per-sector proximity readouts. Works with no map or TF.
When to reach for it
Laser Scan is the close-range obstacle view: the raw lidar return drawn all around the robot, which sits in the middle, one point per range reading, with range rings and the nearest point on each side. It needs no map and no TF, so it works the moment the scan topic is up. For the robot on its map, with paths and hold-to-place nav goals, use Map 2D (Pro).
Worked example: TurtleBot 4 RPLIDAR
Scan Topic /scan, Message Type sensor_msgs/msg/LaserScan, the TurtleBot 4's RPLIDAR default. Drop Max Range (m) from the 30 m default to something room-sized, say 10, so a stray return through an open doorway doesn't blow out the scale. Show Range Stats is on by default: the nearest point and the closest return on each side sit next to the scan, on widgets big enough to fit them.
Watch out for
- Max Range (m) and Min Range (m)filter the data itself, not just the viewport: returns outside that band are dropped before they're drawn. Set Max Range (m)below your lidar's real range and distant points vanish, they don't zoom out of frame.
- Max Message Rate (Hz) defaults to 15, and the widget keeps only the latest scan, not a queue: a faster lidar still only shows its newest sweep at redraw time, not every scan it publishes.
- Pinch-to-zoom is view state only, never saved to config: leave the widget and come back and it resets to 1x.
Configuration fields
The topic this widget reads from. While connected, tap to pick one the robot advertises.
The ROS message type, like sensor_msgs/msg/Image. Fills in when you pick a topic.
Messages per second this widget takes from the topic. Lower saves data, higher shows more.
0.1 to 60, step 0.1Scale the view to the farthest returned point. Max Range acts as a ceiling.
Nearest point and the closest point on each side. Hidden on small widgets.
Color each point by its distance, near to far, instead of one flat color.
Color of the scan points when Distance Gradient is off.
Draw a faint ray from the sensor to each point.