How to manage magnitudes of scale? (as in the VR BBC Home experience)

In the news post about the BBC Home VR-production they mention the challenge of dealing with scale and that the earth is properly scaled 1:1 while at the same time showing “normal” scale in the foreground (hands and astronauts around the ISS.

What needs to be done to handle such a world setup? Furthermore, how could one use World Composition and Level Streaming to descend to ground to one or more particular city locations. I would expect some form of Local Camera Frame and floating point depth buffer.

By the way, totally awesome work on this guys at Rewind! Folks, checkout Rewind’s BBC ‘Home’ page.

Any hints and tips greatly appreciated.

Best regards,
Patric