running and generating a pointcloud (.las)

[cfessler]

i successfully installed the loam following the guide, but now i am stuck a bit. Can you guide me how to generate a pointcloud out of that.

as far as i have understood i have to choose the ros every time i open the console:
source ~/catkin_ws/devel/setup.bash

then i run
roslaunch loam_horizon loam_livox_horizon_imu.launch
to get the data from lidar and IMU?

whilst
rosbag play YOUR_DOWNLOADED.bag - in my case rosbag play 2020_open_road.bag
will add the lidar data to the file?
i do not really get it and to be honest i did not unterstand the ros documentation.

So this is the point where i am standing, is there someone able and willing to point me into the right direction?
When looking for the points mentioned i found the line
rosrun pcl_ros pointcloud_to_pcd input:=/velodyne/pointcloud2
which looks like refering to the subscibe to /velodyne_cloud_registered and register, but i dont get it and i dont really get how the magic works. And what ist meant by registering them together?

Anyone who is able to help me with that?

[telemething]

Are you familiar enough with ROS to know that it publishes ‘messages’ on ‘topics’? - Mark West On Jun 12, 2020, at 4:38 AM, cfessler <notifications@github.com> wrote:  i successfully installed the loam following the guide, but now i am stuck a bit. Can you guide me how to generate a pointcloud out of that. as far as i have understood i have to choose the ros every time i open the console: source ~/catkin_ws/devel/setup.bash then i run roslaunch loam_horizon loam_livox_horizon_imu.launch to get the data from lidar and IMU? whilst rosbag play YOUR_DOWNLOADED.bag - in my case rosbag play 2020_open_road.bag will add the lidar data to the file? i do not really get it and to be honest i did not unterstand the ros documentation. So this is the point where i am standing, is there someone able and willing to point me into the right direction? When looking for the points mentioned i found the line rosrun pcl_ros pointcloud_to_pcd input:=/velodyne/pointcloud2 which looks like refering to the subscibe to /velodyne_cloud_registered and register, but i dont get it and i dont really get how the magic works. And what ist meant by registering them together? Anyone who is able to help me with that? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub<#12>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AJ7RBI2MSAGB3I3STSEWWR3RWIHSJANCNFSM4N4IA2ZA>.

[cfessler]

Are you familiar enough with ROS to know that it publishes ‘messages’ on ‘topics’? - Mark West

thank you for your reply and trying to point me in the right direction,
more or less but i would not say familiar; in my own words: ROS publishes what i gets from lidar via messages and if i understand the graph from rqt_graph right there happens some magic.
BUT what i do not understand is: it looks to like it is serial data (messages) so it must be somehow processed to get a map (or better pointloud).
NEW (didnt work the times i tried that before) when running
rosrun pcl_ros pointcloud_to_pcd input:=/velodyne_cloud_registered it now saves .pcd-files
please see rosgraph, is it right this way?

I am not so sure now, how can i proceed with those files? i need to register them somehow isnt it? what should be my next steps?