Missing the navigation when using kmall_to_ros_bag.py

[Kurtaja]

Hi, I'm trying to use the kmall_to_ros_bag.py script with the aim to obtain a point cloud file from it. This is how I call the script
'python kmall_to_ros_bag.py -o myBagFile.bag myKmFile.kmall'
, which creates the 'myBagFile.bag' file ok. Then I convert it to a pcd file with this script,
"
import rosbag
import sensor_msgs.point_cloud2 as pc2
import numpy as np
import open3d as o3d

def bag_to_pcd(bag_file, topic, output_pcd_file):
accumulated_points = []

with rosbag.Bag(bag_file, 'r') as bag:
    for _, msg, _ in bag.read_messages(topics=[topic]):
        pc_data = pc2.read_points(msg, field_names=("x", "y", "z"), skip_nans=True)
        pc_np = np.array(list(pc_data))
        pc_xyz = pc_np[:, :3]
        accumulated_points.append(pc_xyz)

# Concatenate all points
if accumulated_points:
    all_points = np.concatenate(accumulated_points, axis=0)
    point_cloud = o3d.geometry.PointCloud()
    point_cloud.points = o3d.utility.Vector3dVector(all_points)
    o3d.io.write_point_cloud(output_pcd_file, point_cloud)

if name == "main":
bag_file = "myBagFile.bag"
topic = "mbes/pings"
output_pcd_file = "myPclFile.pcd"

bag_to_pcd(bag_file, topic, output_pcd_file)

"
, which also makes the 'myPclFile.pcd' file ok. However, when displaying the pcd file in a point cloud viewer, all the scans end up in the same spot, as if the vessel was not moving (which it is). I'm sure there must be a dead simple detail that I'm missing, but I'm not able to figure how. Do you have the possibility to show me how I can make sure that I get the navigation, attitudes as well as compensation for svp into the exported files?
Kind regards

[rolker]

As is, the kmall_to_ros_bag.py file does not save the navigation in the ROS bag file. For my use case, I already had the navigation available in another ROS bag file so I only needed properly timestamped PointCloud messages.

The script could be extended to also save the nav data. We'd need to think a bit about the best ROS message(s) to use for the nav data.