Getting Started
This page takes you from an unopened sensor to your first live scan in Houdini.
Install the asset
Grab JV-RPLidar_In-vX.Y.hdalc from your Gumroad library.
otls folder
- Windows —
C:\Users\<you>\Documents\houdini22.0\otls\ - macOS —
~/Library/Preferences/houdini/22.0/otls/ - Linux —
~/houdini22.0/otls/
If the folder doesn't exist yet, create it. On Houdini 21 the folder is houdini21.0 instead.
Or use Assets ▸ Install Digital Asset Library to pick it up without restarting.
The node then appears in the SOP tab menu under JV ▸ RPLidar In.
Indie / Apprentice only
The asset is saved as .hdalc, which loads in Houdini Indie and Apprentice but not in commercial (FX/Core) licenses.
Updating
When a new version arrives, delete the previous .hdalc file before adding the new one — two files defining the same asset will collide. The internal node type never changes between versions, so your existing scenes pick up the new version automatically. Nothing to relink.
Connect the hardware
The sensor
RPLidar In was developed against the Slamtec RPLIDAR A2M12 — a 360°, 16 m range, spinning laser scanner. Other A2-family units should behave the same. The sensor stays silent until Houdini commands the motor to spin, so no lights or sound when you first plug it in is normal.
The two cables
RPLIDAR units use two separate leads — both must be connected for a scan:
The motor lead can go to a plain charger — it doesn't need to be the same machine.
The USB/UART adapter
The sensor connects through a Silicon Labs CP210x USB-to-serial adapter, which enumerates as a COM port on Windows (the driver ships with Windows 11, so it installs automatically). Once connected, Windows gives the adapter a COM port (e.g. COM3).
The baud-rate switch must be at 256000
The adapter has a baud-rate switch, and the A2 family needs it set to 256000. At the wrong setting the device is completely silent — no error, no points, nothing to diagnose. Check this first if your first scan comes up empty.
See your first scan
Create an RPLidar In SOP inside a Geometry object.
Set Mode to Live.
Display the node in the viewport. The motor spins up over about two seconds, then a ring of points appears — one point per laser return. Empty space in front of the sensor produces gaps; walls and objects produce dense arcs.
Lots of gaps is normal
On an open desk, most laser returns hit nothing in range and come back invalid — filtered out before they reach you. More than half of every rotation can be empty. Point the sensor at a wall to see a dense arc. See Modes → invalid returns.
If nothing appears, press Test Sensor to print the sensor's identity, health, and available scan modes to the console, then check Troubleshooting.
Set your working scale
Sensor distances are real-world meters. The Units per Meter parameter maps them to Houdini units:
1(default) — work in meters. A wall 3 m away lands 3 units from the origin.100— work in centimeters.0.5— shrink the world to half size.
Finding the port
Leave the node's Port parameter blank and it auto-detects the CP210x adapter. If auto-detect picks the wrong device (e.g. you have several serial adapters), set the port explicitly — for example COM3 on Windows.
One program at a time
A serial port can only be opened by one process. If Houdini can't open the sensor, make sure no other program holds the port — a separate tester app, another Houdini session in Live mode, or a stale process. Set Mode → Off in any session you're not actively using.
Where to go next
- Learn every mode and control → Using RPLidar In.
- Develop without the sensor connected → Recording & Playback.
- Drive a simulation from the live points → Live Simulation.
- Something not working → Troubleshooting.
