How to transform one point cloud on the time of t-1 to the point cloud coordinate on the time of t? about nuscenes-devkit HOT 5 CLOSED

@emilyemliyM an example of how to transform a point cloud from some time t_n to t₀ can be found here:

Modifying it to work for transforming a point cloud from from t_n to some other time t_m should be relatively trivial - in particular, you would need to get ref_from_car and car_from_global from t_m (rather than t₀)

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@emilyemliyM an example of how to transform a point cloud from some time tn to t0 can be found here:

nuscenes-devkit/python-sdk/nuscenes/utils/data_classes.py

Line 115 in 9cba592

trans_matrix = reduce(np.dot, [ref_from_car, car_from_global, global_from_car, car_from_current])

Modifying it to work for transforming a point cloud from from tn to some other time tm should be relatively trivial - in particular, you would need to get ref_from_car and car_from_global from tm (rather than t0)

Hi, really thanks to the reply.

I have another question about the param in the setting:
what's the meaning of the "ref_chan"? Does it mean "Lidar" string or a token , or anything else? How to use it?
Could I have an example of the use of the function?

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@emilyemliyM the input for ref_chan would be the sensor name (as a str) you want to map the point clouds to (e.g. LIDAR_TOP, RADAR_FRONT)

You can see an example usage here:

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@emilyemliyM an example of how to transform a point cloud from some time tn to t0 can be found here:

nuscenes-devkit/python-sdk/nuscenes/utils/data_classes.py

Line 115 in 9cba592

trans_matrix = reduce(np.dot, [ref_from_car, car_from_global, global_from_car, car_from_current])

Modifying it to work for transforming a point cloud from from tn to some other time tm should be relatively trivial - in particular, you would need to get ref_from_car and car_from_global from tm (rather than t0)

Thanks for the reply!
I want to know that does this method work for two keyframes of point cloud data as well? I want to conduct the coordinate transform between two key frames.

Thanks !

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Yes, it should work for two keyframes, as long as your provide the appropriate transformation matrices

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