Parent frame of host_vehicle_location incorrect

[jola6897]

Hi,

I think the parent frame of host_vehicle_location in SensorData is incorrect.

It states that the The parent frame of host_vehicle_location is the sensor frame. But inside BaseMoving e.g. the orientation is defined like this: The relative orientation of the moving object w.r.t. its parent frame, noted in the parent frame. This would mean the orientation of the sensor frame is given in the sensor frame. Therefore the orientation would always be the identity.

As far as I can see the assumption is that the origin and orientation of the BaseMoving center is equal to the sensor frame (This is why the bounding box need not to be set) and the parent frame shall be inertial e.g. ENU (east-north-up), or Ground Truth.

Could you confirm that my finding is valid and that my assumption is correct please?

[pmai]

I think the sentence stating that the parent frame is the sensor frame was added erroneously during a clean up (2740f2d), which assumed that since it is in SensorData it should be in the sensor frame, but it should not. The host_vehicle_location should be in the global coordinate system, and it should be clarified that it indicates the vehicle position in the same way as HostVehicleData does (and while we are at it, we should clarify whether either point to the center of bounding box, the projected rear axle or something else).

[u21n80]

Hi @pmai, just to clearify since this is SensorData. In your opinion which of the following two defintions would then be more correct:

1. host_vehicle_location describes the position and orientation of the sensor frame in ENU/Ground Truth coordinates. This would be basically directly what the sensor measured hence this is in SensorData.
2. host_vehicle_location describes the position and orientation of the vehicle frame (e.g. center of rear axle) in ENU/Ground Truth coordinates. Whatever the sensor measured would need to be transformed into the vehicle frame using the mounting_position information. This can be very difficult if the sensor is not mounted rigidly on the vehicle. Also most IMU sensors do not provide an angular acceleration which is needed to account for the lever between sensor frame and vehicle frame when computing the acceleration of the vehicle frame.

For me option one is more consistent with the rest of SensorData as all measurements here are already given in the sensor frame and it is also more convenient to use. But the name host_vehicle_location might be confusing for some.

BR Jonas