How was ZBrush used, and why?

ZBrush was used as the sculpting tool when it came to creating both the bigger and smaller details in the troll's topology. A base mesh was created in Maya, which we then heavily pimped out in ZBrush. This data was in turn exported as a huge displacement map. Finally everything was put together and rendered in Houdini.

ZBrush was the only weapon of choice as the sculpt we did had a polygon count which exceeded 500 million. There are no other commercialy available packages that can do this as far as I know, so the HD sculpting option was a real life saver.

Due to a restriction in the size of the displacement map we had to export several maps and stitch them back together into one map which measured 16,000 x 16,000 pixels.

We only used approximately five or six SubTools on the troll since the HD sculpt enabled us to have much more detail in each part.

The various texture maps were approximately 12,000 x 12,000 pixels each, going well beyond a file size of 1 GB per map. We used maps for diffuse, specular, reflectivity and such. I really can't remember the exact number of different render passes we ended up with, but we usally start out with the essential ones and then eventually render out more as the compositors start to demand it.