Radar speed & egomotion raw data

[shawrby]

Hi,

Thank you for your awesome work!

1) Is the speed of radar raw data a relative speed with meter/second(m/s) unit? How should the ego-motion compensated speed be extracted?

2) What's the meaning the each parameter and value in egomotion/egomotion2.json?

Thanks in advance.

[TamasMatuszka]

Hi,

I collected the answers to your questions.

1. The raw radar data is the radial speed with a meter/second unit, you can find the detailed sensor description here: https://www.smartmicro.com/fileadmin/media/Downloads/Automotive_Radar/Sensor_Data_Sheets_76-81GHz/UMRR-11_Type_132_Automotive_Data_Sheet.pdf

You need the ego-motion only if you want to transform it into an absolute coordinate system.

2. egomotion.json parameters: key: camera frame id, value: RT matrix from body coordinate system to ECEF egmotion2.json parameters: key: camera frame id (like in egomotion.json) value is a dictionary where:
   • RT_ECEF_body is the same transformation matrix as in egomotion.json
   • enh_sep is the latitude, longitude, height separation, i.e. GNSS error
   • rph_sep is the roll, pitch, heading separation, i.e. IMU error
   • time: GNSS+INS device timestamp
   • time_host: synchronized host timestamp (from camera metadata)

[shawrby]

@TamasMatuszka

Thank you for detailed reply!

But there is no egomotion2.json file in full dataset. That is, only the egomotion.json file exists.

Therefore, ego-motion cannot be compensated with only RT_ECEF_body information. Is my understanding correct?

[TamasMatuszka]

@shawrby You are right, not every sequence has an egomotion2.json file. However, egomotion.json also contains the RT_ECEF_body information that can be used for compensation (we also used it also during our experiments for collecting more than one LiDAR sweep).