3D LiDAR -> .bag files -> lidar_bev ?

[Petros626]

hey guys,

i am currently having problems understanding how the package works. as you listed, the package expects an input and gives an output.

Input: sensor_msgs/Pointcloud2 (binary_blob?)
Output: sensor_msgs/Image

is it possible to implement my streaming pipeline with this or are the conditions wrong.

Thanks for any kind of help

[beltransen]

HI @Petros626 ,
I'm not sure if I understand the issue. There are two options to use this repository:

• The online ROS node, where the input and outputs are the topic messages you stated.
• The offline mode, to generate the BEVs for KITTI point clouds, where the input and output are files in the disk (The instructions to set the right folder structure are given in the README).

Hope it helps

[Petros626]

Hey @beltransen,

thank you for your quick response.

I'm not that familiar with ROS and the terms yet, sorry. The online method is to be understood like a livestream of the LiDAR data, which were transformed in the BEV, I guess?

So the important question I can only use the package in combination with these messages, i.e. other messages as input are not compatible? Or do I have to write some kind of converter, e.g. from int to double or something, because each input expects its own data type?

is the package only suitable for the velodyne lidar or also for others? would i have to write my own launch file?

Thank you very much for your help!

[beltransen]

Hi again,

to use the package you should first understand how ROS works. Please, refer to the ROS tutorials. Regarding your questions:

The online method is to be understood like a livestream of the LiDAR data, which were transformed in the BEV, I guess?

Yes.

So the important question I can only use the package in combination with these messages, i.e. other messages as input are not compatible? Or do I have to write some kind of converter, e.g. from int to double or something, because each input expects its own data type?

The inputs need to be of the defined data types. Therefore, if your sensor stream is published in a different format, you should write a converter node.

is the package only suitable for the velodyne lidar or also for others? would i have to write my own launch file?

Any LiDAR model may be used, as long as the cloud is published in the desired format. However, you may need to modify the provided launch file to set the topic names accordingly.

[Petros626]

Hey @beltransen,

thank you for your support and the quick answer.

OK, I'll take a closer look at the launch file, thanks in any case.