In the Guinness commercial titled noitulovE, the audience follows three appreciative Guinness drinkers from their London pub back in time to the primordial ooze where their mudskipper ancestors are clearly un-impressed with the local drinking water. As the three drinkers regress, they pass through a series of environments that showcase their passage back through time. Framestore CFC’s Commercial division relied on Houdini’s procedural workflow to create both the urban and natural CG environments during this temporal transition.

Houdini was used to populate London with architecture that would shift and change as time reverses. This was accomplished using Houdini’s copy stamping feature controlled by attributes painted into the landscape. Pockets of metaballs were then used to define the disappearing urban environment while special controls were set up to fine tune the effect. For example, a parameter was created to define the frequency of churches popping-up as the low-rise London emerged.

Re-using Procedural Systems

The base system used to populate the cities was then modified and re-used for trees, bushes, grass and rocks. By taking advantage of Houdini’s procedural approach it was easy to re-implement the best ideas throughout the production. The key to generating the digital environments was Houdini’s ability to create many variants of the copied elements procedurally while maintaining creative control over how they were distributed. "We created a base system in Houdini," says Andy Boyd, Head of 3D Commercials, "and once the system was finished we were able to easily adjust it to create many versions.”

Houdini also provided an efficient workflow for generating all of the trees. In about five weeks Framestore CFC set up the complete DNA of a generic tree that served as the template for the automatic generation of many unique types of trees. The resulting set of flora tools was based on a combination of L-systems and copy stamping. The artist could paste branches, twigs and leaves onto the points of existing trunks and branches using either a fully procedural tree or pre-modeled geometry.

SCRIPTING FOR ARTISTS WITH VEX BUILDER

For a sequence that shows an “un-eroding” cliff and waterfall, a surface was deformed using a custom modeling operation created with Houdini’s VEX scripting language. This custom script was built by an artist using the VEX Builder - Houdini’s node-based approach to transparently generating VEX code. These networks made it easy to control the changing shape of the landscape while adding in turbulent noise to enhance the effect. Artists found the VEX Builder easy to use, and were able to quickly evaluate the results then re-use the same technique in many different shots.

Similar VEX scripts were used to randomize the orientation of leaves on the trees. Grass was added to the shots near the end of production and the artists were able to make use of existing techniques for rapid prototyping and execution.

The resulting productivity has made Houdini an integral part of Framestore CFC’s commercial pipeline, allowing the studio to tackle complex shots traditionally associated with high-end feature film productions.