Python: SPG Composite AOV#

An SPG node whose input is a lidar rather than a camera. A lidar PointCloud is a composite AOV: several named channels published together under one render var, instead of the single image a camera AOV gives you. This node reads the Coordinates and Counts channels, counts the sweep’s returns by distance, and publishes a bar chart on its own AOV.

The scene the sensor sweeps, from a second render product with an ordinary camera. The orange post is the lidar; the grey box is 6 m away and the tan box 12 m away and twice as wide:

The lidar scene, a sensor post and two boxes

What the node made of that sweep, one bar per box:

SPG composite AOV example output, a histogram of lidar returns by distance

The chart is two bars, one per box in the scene, because the scene contains nothing else the sensor can reach. main.py then rebuilds the same histogram on the host from the same channels and compares it bar by bar, so the example checks itself rather than being read by eye.

Prerequisites#

Python 3.10-3.13
uv
An NVIDIA RTX-capable GPU and a supported driver

Running#

uv run main.py                                # CUDA
uv run main.py --scene lidar_scene_slang.usda # Slang

One renderer.step() fills two render products: the lidar and its histogram, and an ordinary camera view of the same scene. See Read a Sensor Composite for what a composite AOV is and how the channels are bound.