[criticaltinker]

> I think this method is less attractive to training acceleration scenario

The proposed hash based encoding function is not differentiable, so it doesn’t appear this method can be used for training at all.

I’m not aware of any hash functions that are analytically differentiable, so to support efficient back-propagation I suspect that some fundamental changes to this method would be necessary.

[ffast-math]

You could still optimize the prototypes, so fine-tuning with this in place would be possible (see, e.g., [1]). But we don't yet have data on how well this would work using our exact method, how early in training you could do the op replacement, etc.

[1] http://openaccess.thecvf.com/content_ECCV_2018/html/Sanghyun...