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ros-perception / radar_msgs

A set of standard messages for RADARs in ROS
Apache License 2.0
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Question: What is the meaning of the sign of doppler_velocity? #11

Open Aposhian opened 3 years ago

Aposhian commented 3 years ago

Does a positive sign in doppler_velocity in RadarReturn denote moving toward the sensor, or away from the sensor?

SteveMacenski commented 3 years ago

@aaronfultonnz @radarAaron What's the general convention in RADAR-land? We should update the description to include that explicitly

SteveMacenski commented 3 years ago

@Aposhian this message uses the standard in radar sensor conventions, if you know what that is, we can update that in the message to be explicitly clear. Unfortunately, I'm not currently a radar user myself, I was acting as the responsible party to help guide the discussions for establishing this standard.

A NOAA article says:

Since Doppler velocities are negative (component toward the radar) along the western edge of the display and positive (component away from the radar) along the eastern edge, the wind obviously is blowing from west to east at the height of the edge of the display.

Which makes me believe that doppler velocities are negative towards the radar and positive away from the radar. But I'd want to find something citable in the robotics domain to make sure that convention holds.

aaronfultonnz commented 3 years ago

@SteveMacenski @Aposhian I believe the convention (as far as anything in the radar world is standardised), is as Steve has pointed out, that the negative is toward the sensor and the positive away. This is how our product works, but I have not been able to find a definitive source to back this up as any kind of industry standard.