Driver keeps publishing pointclouds when sensor is not connected

[MCFurry]

We're typically used to sensor drivers only publishing a pointcloud when the sensor outputs data.

However, we noticed that the USS and Radar drivers output pointclouds on a fixed rate, also when there is no sensor connected.
The pointclouds are then empty, but so are they when the sensor IS connected but no objects are detected.

The diagnostic message reflects a "Timeout" in case the sensor is not sending new data, so that is nice, but is there a rationale to still send empty pointclouds in these cases?

[davemue]

Thanks for the question, @MCFurry!

The sensor drivers were designed to publish empty point clouds to allow downstream components to actively remove objects that have left the field of view.
We did consider suppressing empty messages, but the added complexity didn’t provide significant performance benefits. The diagnostic "Timeout" message helps distinguish between a lack of detections and a missing data stream from the sensor.

If I understand your suggestion correctly, you're proposing that the drivers should publish point clouds when a sensor is connected, and stop publishing entirely when no sensor is present.

[MCFurry]

Exactly! Sending empty pointclouds when nothing is detected is perfectly fine for the reasons you describe. But when no sensor is connected (anymore) I think it also makes sense to stop sending sensor data.

[davemue]

@MCFurry I understand that this could make sense.

Unfortunately, we don't have resources to address this right now. If you'd like to submit a PR implementing this change, we'd be happy to review it.

Thanks for bringing this to our attention!

[MCFurry]

Something like this to start with?
#21

[MCFurry]

Hi @davemue , I understand you're busy with other tasks, but can you let me know your thoughts about my PR?
Would be good if we can keep this going, thx!