Using Voxblox in planners that do not support ESDF

ethz-asl / voxblox

A library for flexible voxel-based mapping, mainly focusing on truncated and Euclidean signed distance fields.

BSD 3-Clause "New" or "Revised" License

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Using Voxblox in planners that do not support ESDF #181

Open dario-ljubic opened 6 years ago

dario-ljubic commented 6 years ago

Hello, first of all, thank you on making this excellent code public!

I am currently experimenting with the Voxblox and looking into its possibilities. The recent change on the possibility of local scene reconstruction looks and works great. Now, I would also like to use it in my planner, but it does not operate with ESDF. I have tried taking surface point cloud from TSDF and using point cloud to laser scan converter which is able to create a 2D-like scan that I can use in my planner.

However, with the frequency of ~10 Hz, it is too slow. I was wondering do You maybe have an advice on what is the best way to convert TSDF/ESDF to laser scan or to obtain something like laser scan?

Thank You in advance!

ZacharyTaylor commented 6 years ago

Thanks for the interest in the code. If "publish_tsdf_info" is set to true, then voxblox should output the surface pointcloud whenever the TSDF changes.

So if you are only seeing output at 10 Hz there are four possibilities

We have a bug
The "min_time_between_msgs_sec" parameter has been set to ~0.1. In this case just set it to 0.0 to prevent it throttling your data.
Your input data is coming in at 10 Hz. In this case publishing faster would not add any information
Voxblox is overloaded and dropping messages. If this is happing try decreasing the max ray length or increasing voxel size.

For getting a laser like output your best options are either the surface pointcloud or the mesh_pcl topic. Why are you not just directly using the lidar output, is voxblox needed to denoise or downsample the data?

dario-ljubic commented 6 years ago

Thank You for the reply!

Whenever I enable "publish_tsdf_info" it slows down everything quite a bit. Following your advices I have found out that the "voxel_size" was the problem. Now, combining "voxel_size" and "max_block_distance_from_body" I get the frequency above 15 Hz.

Yes, that was the idea - to denoise and downsample data and to have a good reconstruction quality on the way. Also, I have seen the "mesh_pcl" topic you mentioned, but when I try to find "output_mesh_as_pcl_mesh" I only find it in readme files.