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waymo-research / waymo-open-dataset

Waymo Open Dataset
https://www.waymo.com/open
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Question about the flow wrap code for the occupancy_flow prediction. #567

Open lkyllx0 opened 1 year ago

lkyllx0 commented 1 year ago

In the metric description, it says we get Wk based on Fk. But in the coded provided by waymo, we are getting W(k-1) based on Fk since it is the backward flow. Anyone has some idea about this ? image

rezama commented 1 year ago

Could you link to the code where you see a discrepancy with the description?

lkyllx0 commented 1 year ago

Thanks for your reply.
It is the _flow_warp function.
https://github.com/waymo-research/waymo-open-dataset/blob/master/waymo_open_dataset/utils/occupancy_flow_metrics.py

Based on my understanding, warped_origin indicates the W(k-1) occupancy not Wk. Could you please correct me if I am wrong? Thanks.

rezama commented 1 year ago

warped_flow_origin[k] is W_k.

It is obtained by applying Fk to O{k-1}.

O_{k-1} is stored in flow_origin_occupancy[k] since it is the base/origin for the k-th flow field.