My guess is that this image is made with morphs of a kind and not collision detection. Collision detection wouldn't have made depressions, it would only have stopped the character from going thru the sheet. Then again, Ockham wrote his Eureka script that can do something like this. So perhaps THAT is what was used? It looks very cool.

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You just can't put the words "Poserites" and "happy" in the same sentence - didn't you know that? LaurieA
  Using Poser since 2002. Currently at Version 11.1 - Win 10.