Clarification needed: spherical coordinates (r, θ, φ) zero-values for Data_Type 1, 3, 5, 8 #245

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2025-06-18T17:10:34+02:00

math-1307 commented

2025-06-18 17:10:34 +02:00

(Migrated from github.com)

Clarification needed: spherical coordinates (depth, theta and phi) zero‑values for Data_Type 1, 3, 5, 8

Page: Livox‑SDK Communication Protocol – §3.3 Point Cloud/IMU Data (Data_Type)

Issue Summary

With respect to section 3.3, it's understood that for Cartesian output, no‑detection points (Return 0: E.g. pointing at the empty sky) are represented as (0, 0, 0). However, the behavior for spherical coordinate output (Data_Type 1, 3, 5, and 8) under no‑detection conditions is not specified.

What’s Missing

For the spherical formats corresponding to Data_Type 1, 3, 5, and 8, please clarify whether:

(azimuth) and (zenith) are also zeroed out, or
(azimuth) and (zenith) still reflect the actual scan angles where no detection occurred.

Knowing whether theta and phi retain scanning direction even when depth is 0 is crucial for correct interpretation of “sky” or no‑return points.

Additional Question

Does livox_ros_driver or livox_ros_driver2 offer a ROS topic or configuration option to publish point clouds directly in spherical coordinates (r, θ, φ)?

Thank you for reviewing this; clarifications here would significantly aid users handling spherical point-cloud data!

### Clarification needed: spherical coordinates (depth, theta and phi) zero‑values for Data_Type 1, 3, 5, 8 **Page:** [Livox‑SDK Communication Protocol – §3.3 Point Cloud/IMU Data (Data_Type)](https://github.com/Livox‑SDK/Livox‑SDK/wiki/Livox‑SDK‑Communication‑Protocol#33-point-cloudimu-data-data_type) --- #### Issue Summary With respect to section 3.3, it's understood that for Cartesian output, no‑detection points (Return 0: E.g. pointing at the empty sky) are represented as `(0, 0, 0)`. However, the behavior for spherical coordinate output (Data_Type 1, 3, 5, and 8) under no‑detection conditions is not specified. #### What’s Missing For the spherical formats corresponding to Data_Type 1, 3, 5, and 8, please clarify whether: - (azimuth) and (zenith) are also zeroed out, or - (azimuth) and (zenith) still reflect the actual scan angles where no detection occurred. Knowing whether theta and phi retain scanning direction even when depth is 0 is crucial for correct interpretation of “sky” or no‑return points. --- #### Additional Question - Does `livox_ros_driver` or `livox_ros_driver2` offer a ROS topic or configuration option to publish point clouds directly in **spherical coordinates** `(r, θ, φ)`? --- Thank you for reviewing this; clarifications here would significantly aid users handling spherical point-cloud data!

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Reference: mmr/Livox-SDK#245

Clarification needed: spherical coordinates (r, θ, φ) zero-values for Data_Type 1, 3, 5, 8 #245

Clarification needed: spherical coordinates (depth, theta and phi) zero‑values for Data_Type 1, 3, 5, 8

Issue Summary

What’s Missing

Additional Question

Clarification needed: spherical coordinates (depth, theta and phi) zero‑values for Data_Type 1, 3, 5, 8