Cartographer_ros: Live 3D mapping?

[MrGitGo]

I am able to get a 3d point cloud with the assets_writer and I can also view it. My question would be now if I can see the 3d point cloud live, while I am mapping? I want to implement a navigation and it would be good if I can detect dynamical obstacles. So, is something like online 3d mapping possible? I mean 3d mapping without using bag files. I want to start rviz and when I start cartographer I want to see that google cartographer is drawing 3d maps not 2d.
Or better said a real-time loop closure in (real) 3d

[MichaelGrupp]

I want to implement a navigation and it would be good if I can detect dynamical obstacles.

This is something that would be built on top of Cartographer. For example, here's a recent approach for building temporal 3D voxel layers that can be used with the ROS navigation stack: https://github.com/SteveMacenski/spatio_temporal_voxel_layer

[MrGitGo]

This looks great! But do you know if it's possible to build a real time point cloud?

[ojura]

There is a way to do it in rviz, but it's slow, and the points will not follow trajectory optimization. Just set the accumulation delay of the PointCloud2 display of the topic /scan_matched_points to something large.

[MrGitGo]

Thanks

[MrGitGo]

I don't know why but I couldn't find the accumulation delay of the pc2 in rviz. I have the topic scan_matched_points2 in pc2 selected but can't see it. I have just a decay time

[ojura]

That’s it.

[Duke-Allen]

@Semih67 @MichaelGrupp
Hello, I am using a 16-lines LIDAR and IMU to build 3D map by cartographer.
I tun the parameters and run it with no error, the results are as follows:

There is a big gap with the real environment. I think the map is messy. What is the problem of this result? How can I solve it?
This is the validate result of my bag:

• E0227 22:30:57.092067 19056 rosbag_validate_main.cc:365] Average IMU linear acceleration is 10.6084 m/s^2, expected is [9.5, 10.5] m/s^2. Linear acceleration data should include gravity and be given in m/s^2.
  I0227 22:30:57.093359 19056 rosbag_validate_main.cc:398] Time delta histogram for consecutive messages on topic "/IMU" (frame_id: "imu"):
  Count: 37968 Min: 0.004133 Max: 0.016211 Mean: 0.010000
  [0.004133, 0.005340) Count: 2 (0.005268%) Total: 2 (0.005268%)
  [0.005340, 0.006548) Count: 3 (0.007901%) Total: 5 (0.013169%)
  [0.006548, 0.007756) Count: 8 (0.021070%) Total: 13 (0.034239%)
  [0.007756, 0.008964) Count: 828 (2.180784%) Total: 841 (2.215023%)
  [0.008964, 0.010172) ################### Count: 35958 (94.706070%) Total: 36799 (96.921089%)
  [0.010172, 0.011380) Count: 345 (0.908660%) Total: 37144 (97.829750%)
  [0.011380, 0.012588) Count: 820 (2.159714%) Total: 37964 (99.989464%)
  [0.012588, 0.013796) Count: 1 (0.002634%) Total: 37965 (99.992096%)
  [0.013796, 0.015004) Count: 0 (0.000000%) Total: 37965 (99.992096%)
  [0.015004, 0.016211] Count: 3 (0.007901%) Total: 37968 (100.000000%)
  E0227 22:30:57.094650 19056 rosbag_validate_main.cc:382] Point data (frame_id: "rslidar") has a large gap, largest is 0.101409 s, recommended is [0.0005, 0.05] s with no jitter.
  I0227 22:30:57.094745 19056 rosbag_validate_main.cc:398] Time delta histogram for consecutive messages on topic "/rslidar_points" (frame_id: "rslidar"):
  Count: 3766 Min: 0.100213 Max: 0.101409 Mean: 0.100801
  [0.100213, 0.100333) Count: 1 (0.026553%) Total: 1 (0.026553%)
  [0.100333, 0.100452) Count: 1 (0.026553%) Total: 2 (0.053107%)
  [0.100452, 0.100572) Count: 9 (0.238980%) Total: 11 (0.292087%)
  [0.100572, 0.100691) Count: 33 (0.876261%) Total: 44 (1.168348%)
  [0.100691, 0.100811) ############## Count: 2717 (72.145515%) Total: 2761 (73.313858%)
  [0.100811, 0.100931) ##### Count: 972 (25.809877%) Total: 3733 (99.123741%)
  [0.100931, 0.101050) Count: 25 (0.663834%) Total: 3758 (99.787575%)
  [0.101050, 0.101170) Count: 6 (0.159320%) Total: 3764 (99.946892%)
  [0.101170, 0.101289) Count: 1 (0.026553%) Total: 3765 (99.973450%)
  [0.101289, 0.101409] Count: 1 (0.026553%) Total: 3766 (100.000000%)

Here are my files:
demo_rsldiar_3d.launch
rslidar_3d.launch
mydemo_3d.rviz
rslidar_2d.urdf
rslidar_scan_3d.lua
my data bag