Re: Livox Avia, + Depth cameras and organized point clouds.

Posted by matlabbe on
URL: http://official-rtab-map-forum.206.s1.nabble.com/Livox-Avia-Depth-cameras-and-organized-point-clouds-tp9200p9212.html

Hi,

in ROS, an organized point cloud is a PointCloud2 where height > 1 and you can get NaN 3D points. A dense point cloud would be a PointCloud2 with height=1 and no invalid points. Velodyne can generate organized or dense PointCloud2, ouster generates organized PointCloud2. Organized is the inverse of "is_dense" here: http://docs.ros.org/en/melodic/api/sensor_msgs/html/msg/PointCloud2.html

PCL will use the term organized: https://pointclouds.org/documentation/tutorials/basic_structures.html

A depth image is then referred as organized. For survey scanner, they may generate RGB image + Depth image, or even an organized point cloud with RGB channel for each point. The LAS format can support this. With RTAB-Map, we can export in LAS for convenience. If you feed a depth image to rtabmap, you will be able to export  RGB + Depth and the generated colored point cloud. If you feed only RGB + Lidar scan, you won't be able to export depth image for each RGB frame, only the colored point cloud. However, with some changes to rtabmap-export tool (with --cam_projection option), you could save the depth images from lidar data, as they are generated already here (replacing that function with this one for each camera).

If exporting corresponding depth images to rgb frames based on lidar data is what you want, I could check to add the option.

cheers,
Mathieu