Generating ring and time fields for lidars

[Opletts]

Velodyne lidars publish PointCloud2 messages with the fields array containing :

• x , type : float32
• y , type : float32
• z , type : float32
• intensity , type : float32
• ring , type : uint16
• time , type : float32

ring : Tells us which channel of the lidar the point belongs to.
time : Tells us the relative time at which the point was received during one rotation. If the rotation_frequency is 10Hz, values would vary between 0-0.1s)

Carla only publishes XYZI points, not XYZIRT. I think adding these two fields would be quite useful. I've made changes locally to generate ring in lidar.py and can open a PR for review.

Generating the time field on the other hand is quite difficult. We've already received the binary data in lidar.py so it's impossible to get that field here. I'm guessing changes to the lidar api in Carla would be required to make this possible. Any suggestions?

[joel-mb]

Hi @Opletts!
Please, feel free to open a PR to add the ring field.
Regarding the time field, you are right. Modifications in CARLA would be required. I suggest opening an issue in the CARLA repo or contribute with your changes there.