Hi!
I was wandering what sort of geometry architecture is used in new Houdini 12. Of course is is some special customized data structure, but I'm curious on what kind of standard data structure it is based (half-edge data structure?)

Thnk you!

There's a pic of it labelled “Geometry Structure” on this page:
http://www.sidefx.com/docs/hdk12.0/hdk_geometry_intro.html [sidefx.com]

ie. Polygon Soup. The basic data structure hasn't changed in H12, but rather, it's implementation.

Fancier data structures are built when they're needed, e.g. in GQ (as the page Edward linked to describes), since most operations don't require them and they can take up a lot of memory.