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valeoai / RADIal

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Prepared dataset radar doppler clarification #11

Closed samberngit closed 2 years ago

samberngit commented 2 years ago

Hello, When looking at the prepared dataset, specifically at the doppler data in radar_PCL, I can not find an explanation on how to interpret this data and can not find an example of usage of this specific data. This is for example not used in the loader/example_dataset.ipynb file. In the loader/dataset.py file there is a definition of the radar_PCL data as "range,azimuth,elevation,power,doppler,x,y,z,v". The doppler value is an 8-bit value associated with each datapoint. How is the doppler value to be interpreted and is there an example which I have missed?

jrebut commented 2 years ago

Hi, The Doppler value is coded on a 8 bits data, from 0 to 255 The zero Doppler is at bin 127. Positive Doppler, meaning object going away from the sensor, is from 128 to 255 Negative Doppler, meaning object coming toward the sensor, is from 0 to 127 Each Doppler bin as a resolution of 0.1m/s That is to say the maximum unambiguous velocity is +/- 12.8m/s, roughly speaking +/-50KpH. Everything above will have ambiguity

samberngit commented 2 years ago

Thank you for the response!