tilting velodyne lidar: pointcloud and tf

edit

Hi,

Im working with a velodyne Lidar sensor to eventually be mounted on a UAV. (Ubuntu 20,5.15.0-46-generic,ROS Noetic)

I understand that the velodyne lidar when in a horizontal position has its axis as defined by ROS REP-103, as seen in the figure (x- forward, y-right, z-up)

With the lidar in the horizontal position and running the ros driver package (https://github.com/ros-drivers/velodyne) with frame_id=velodyne and visualizing the pointcloud, the result is as expected. The pointcloud is shown with the 'velodyne' frame as below.

I then physically tilt the lidar forward (rotate +90 degrees around +y) and set the frame_id=velodyne_vertical and visualize the pointcloud as below.

now since the pointcloud data is collected in the frame frame_id=velodyne_vertical, how can I transform the pointcloud to be represented in the original velodyne frame (frame_id=velodyne)? The lidar mapping package im trying to use requires the pointcloud data to be in the original ROS-REP103 standard.

Any ideas on how that can be achieved? Am i missing something here?

Edit:

TF tree

Edit:

I did just that @ravijoshi, but when visualizing both pointclouds they seem to be coinciding. Doesnt seem to be correct, is it? Here is the original pointcloud in the frame_id=velodyne_vertical

and here is the same pointcloud in the transformed frame base_link

for reference, here is the callback function to transform the pointcloud

void pcCallback(const PointCloud::ConstPtr &msg)
    {
        try
        {
            if (target_frame_.empty() == false)
            {
                if (pcl_ros::transformPointCloud(target_frame_, *msg, *cloud_tranformed_, tf_listener_) == false)
                {
                    ROS_ERROR("Failed pcl_ros::transformPointCloud target_frame:[%s]",target_frame_.c_str());
                    return;
                }

                //BOOST_FOREACH (const pcl::PointXYZ& pt2, cloud_tranformed_->points)
                //printf ("transformed points: \t(%f, %f, %f)\n", pt2.x, pt2.y, pt2.z);

                pub_transformed_.publish(cloud_tranformed_);
            }
        }
        catch (std::exception &e)
        {
            ROS_ERROR("%s", e.what());
        }
    }