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aharley / simple_bev

A Simple Baseline for BEV Perception
MIT License
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"Lift" operation in code #20

Closed Like2021 closed 1 year ago

Like2021 commented 1 year ago

Hi,

Thank you for your research.

Could you give me some tips about "Lift" operation in Code,

may be here:

https://github.com/aharley/simple_bev/blob/be46f0ef71960c233341852f3d9bc3677558ab6d/utils/vox.py#L291-L341

aharley commented 1 year ago

The idea here is: for each 3D coordinate in the mem grid (aka the BEV meshgrid but with a vertical axis), take a bilinear sample at the pixel location where this coordinate projects.

erivera1802 commented 1 year ago

@aharley that means, several 3d cells which are projected to the same pixel will be assigned the same 2D feature?

aharley commented 1 year ago

Yes. But I think it's rare for the features to be exactly the same, because really the 3D coordinates land in floating point (subpixel) locations, and we take bilinear samples.