The recently released Houdini version 8 arguably delivers the best dynamic simulation environment on the market, as well as further improvements to lighting and character tools. All images © Side Effects Software.

Houdini, from Toronto-based Side Effects Software (sidefx.com), has always attracted certain sectors of the high-end 3D animation industry. Lighting, shading and animation improvements in recent versions have only increased its stature among leading industry professionals. The recently released Houdini version 8 arguably delivers the best dynamic simulation environment on the market, as well as further improvements to lighting and character tools. For those who are unfamiliar with developments in recent versions of Houdini, it’s time to take a closer look at this software.

Coming Up on the Outside
Houdini is a bit of a dark horse among 3D animation packages. Throughout its 20-year history, Side Effects have traditionally avoided the volume of aggressive and misleading marketing statements characteristic of its competitors. Many wouldn’t know, for instance, that Houdini was the first 3D animation software to be honored with an Academy Award, or that it was the first package to have a built-in compositor, non-linear animation tools and built-in comprehensive RenderMan support.

Despite this, Houdini has long enjoyed widespread use among many of the world’s largest effects houses, and is responsible for many of the most dramatic visual effects made year after year (including last year’s Stealth). Following improvements to lighting and animation workflow in recent versions, a number of feature animation studios have started to use Houdini as their primary tool. Two of the animated features due for theatrical release in 2006 were created using Houdini (including Disney’s The Wild created by C.O.R.E. Feature Animation).

Lighting, shading and animation improvements in recent versions have only increased its stature among leading industry professionals.

Fully Procedural
For those new to Houdini, its distinguishing characteristic is that it is fully procedural. Houdini has a node-based interface similar to that of many popular compositing and crowd AI packages. This type of proceduralism gives users the ability to go back and change any step in the production workflow at any point, and then have those changes flow through the entire network. It’s kind of like a scripting language with a node based GUI.

Among other things, this kind of proceduralism permits artists to respond quickly to dramatic changes in creative direction. When confronted with such directorial decisions, Houdini users are more likely to smile and say, “sure — not a problem” than die a hundred deaths at the prospect of having to redo two days worth of work because they can no longer undo some step they took back then.

It has been noted that Houdini’s procedural architecture is also part of the reason why it isn’t full of bugs, and new features can be added to new iterations without introducing new bugs.

Large Pipeline Throughput + Highly Recyclable Code
Besides creating a very manageable construction history, proceduralism enables users to create scene files that are easily re-usable on multiple shots. Once properly set up, new input data can be plugged into the head of a procedure, and the final product comes out the other end with minimal additional user time.

In Houdini version 7, a digital asset creation and management system was introduced to facilitate the kind of code re-use common among Houdini users. “Houdini Digital Assets” basically permit the creation of easy-to-use interfaces to complex procedures that are encapsulated below the interface in sub-networks. Things such as character rigs, common effects, or even just regularly used tools for massaging vectors can be bundled up in a single node, with all complexity hidden behind an artist friendly interface. With these digital assets saved to disk they can then be installed in multiple scene files either by hand — or by using a few lines of script. Later, the technical director responsible for managing the digital asset can make an improvement to a rig encapsulated by a digital asset, save the change, and every scene file with that digital asset installed will automatically update.

This kind of code re-usability makes it easy to automate the production of 3D elements for multiple shots across multiple sequences. For effects needed in multiple shots, solo technical directors can use a few lines of Houdini’s native script language to create or modify multiple scene files so as to complete new versions of an element for every shot in a sequence. A possible part of this scenario could be that Houdini uses its excellent unix shell, python, perl, java or xml tools to interface with some external database so as to read in all the unique production data for that shot. This data can be used to select and install the necessary digital assets for that shot, arm them with particular parameter settings from the database and then execute their output. It might take two minutes to launch hundreds of elements. If revisions are necessary, the easy-to-use interfaces possible with digital assets permit entry-level artists to make necessary changes on a shot-by-shot basis.