At the end of the video there is a non-pinhole camera demo; could someone explain what exactly is different about this camera?

I.e. what exactly the video is showing? And what would the video look like if that was a pinhole camera?

> This algorithm is much more efficient than typical ray tracing acceleration methods that rely on hierarchical acceleration structures with logarithmic query complexity.

!?

This is a wild claim to just slip in. Can anyone expand?

How is Google using all these amazing radiant field techniques they're developing?