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Is there a bug in get_sensor_data of nuscenes dataset?

Open Yihanhu opened this issue 6 years ago • 7 comments

Hi, I might find a bug here,

https://github.com/traveller59/second.pytorch/blob/3aba19c9688274f75ebb5e576f65cfe54773c021/second/data/nuscenes_dataset.py#L185

Why you concatenate timestamp channel instead of reflectance?

Yihanhu avatar Jul 29 '19 17:07 Yihanhu

Will np.concatenate(sweep_points_list, axis=0)[:, [0, 1, 2, 3]] be better?

yinjunbo avatar Aug 01 '19 06:08 yinjunbo

Will np.concatenate(sweep_points_list, axis=0)[:, [0, 1, 2, 3]] be better?

My experiment shows that use timestep is better than reflectance, which is confusing.

Yihanhu avatar Aug 02 '19 03:08 Yihanhu

@Yihanhu Do you know that is the reflectance used when training on KITTI? I don't try it on KITTI yet. And could you tell me how much performance is gained when using timestamp on nuScenes according to your experiments?

yinjunbo avatar Aug 02 '19 08:08 yinjunbo

@Yihanhu Do you know that is the reflectance used when training on KITTI? I don't try it on KITTI yet. And could you tell me how much performance is gained when using timestamp on nuScenes according to your experiments?

Yes, it is. I haven't done detailed research yet. For the same configuration, my model somehow cannot even work without timesteps.

Yihanhu avatar Aug 10 '19 18:08 Yihanhu

@Yihanhu The original code stacks all the point cloud frames(~11 frames) into a single frame. I only sample 3 frames from the 11 frames uniformly, and use the reflection channel instead of the timestamp channel. Results on val set shows that using reflection is a little better(21.1/19.7 mAP on 1/8 datasets). If you are still working on nuScenes dataset, we can talk more further.

yinjunbo avatar Aug 21 '19 04:08 yinjunbo

Yes, it is. I haven't done detailed research yet. For the same configuration, my model somehow cannot even work without timesteps.

It seems like the timestamp introduces some bias to overfit the data. I was wondering whether the operation of concatenating the timestamp as the input feature is reasonable or not. I suppose the reason why it works is: When evaluating the validation set, the prediction of the validation data should be similar to those training data with similar/near timestamps.

If this is really the reason behind, the operation of concatenating the timestamp as the input feature is really not reasonable and cannot generalize to real-world scenarios.

pyun-ram avatar Aug 10 '20 09:08 pyun-ram

Hi, how to use more than 4 features as input. for example, can I simply use points[:,[0,1,2,3,4]]?

chyohoo avatar Dec 23 '21 06:12 chyohoo