About timestamp of LiDAR point

[Joanna-HE]

Hi,

Thank you for open sourcing three robot datasets with GNSS, IMU, and lidar data. I would like to use these datasets to test our algorithm, and would like to ask if there is a timestamp for each LiDAR point, if yes, what is the value type of the point's time? Hope to hear from you.

Best regards,

Dongjiao HE

[JonasBchrt]

Hi and thanks for your interest. I am not sure if I understand your question correctly, but maybe this answer helps:

• The topic with the lidar data is /hesai/pandar, which is of type sensor_msgs/PointCloud2. You can find the message definition here.
• Each point cloud has a timestamp in the header, i.e., in /hesai/pandar/header. The header is defined here.
• The structure of the point cloud data is defined in the topic hesai/pandar/fields, which is an array of type PointField, which is defined here.
• If you subscribe to the topic and look at one of the bags, then you can see that the structure includes an element called "timestamp" with an offset of 24 bytes and of type FLOAT64.
• The actual point data is then in /hesai/pandar/data and stored according to the definition in /hesai/pandar/fields, including the timestamps.

[Joanna-HE]

Thanks for your kind and prompt reply, my problem is solved perfectly.