Halon created realtime previs with House of Moves motion capture data for a recent Miller Lite commercial (Break Away From the Crowd). Courtesy of Method Studios.

In today's world of high-tech production, realtime, onset previs is becoming a reality. Just how important is it? If you're familiar with ILM's Zviz, you know that George Lucas believes this interactive previs system utilizing the LucasArts game engine will eventually revolutionize the industry.

Meanwhile, MoCap is becoming more integral to previs, and a major pioneer and the leading developer of optical motion capture solutions is U.K.-based Vicon Motion Systems. In 2004, Vicon acquired Los Angeles-based House of Moves, the longest-standing independent motion capture service bureau in the world. The result: Vicon House of Moves has set up three permanent motion capture stages. Each one is capable of providing realtime previs for their clients to use in a variety of ways.

"We have to remain flexible to enable us to customize workflow on and off set to meet the individual needs of clients and their productions," explains Gary Roberts, President of Vicon House of Moves and the Vicon Feature Unit. "Every production we shoot at HOM, whether it is a feature, commercial, music video, videogame, TV show on or off location always uses on set realtime previs. It is incredibly beneficial for both our clients and in house staff."

Their main stage utilizes more than 70 Vicon MX F40 cameras to capture full body and finger motions along with props, cameras and set pieces in a large capture volume 90'x45'x18' stage. Their second stage has a slightly smaller capture volume but is optimized to use more than 120 MX F40 cameras to capture the performance of actors in their entirety along with audio. Their third stage uses 40 MX F40 cameras and is customized for particular projects.

"Our previs technology allows multiple actors (up to 15), props and set pieces along with tracked cameras to be captured in realtime to drive multiple associated CG characters within any 3D environment," adds Roberts. "We can provide good real time rendering in 3D and 2D, with lighting, particle, textures and shaders. We can also overlay CG characters with video back plates and camera tracks whenever needed. All this can be used on site here at HOM and on location for any shoot whether it's for on set live-action integration, greenscreen or a more traditional motion capture shoot."

Previs is also used to provide immediate playback on set of any previous shot captured to allow directors and animators to review shots on the fly as they shoot and to make on set selections thus speeding up the post production phases. "We also use pre-visualization on set during camera tracking," Roberts points out. "With this technique we capture the position, orientation and lens of multiple virtual cameras on set as they move, while simultaneously rendering the realtime view from each of them into the virtual world; back to the eye piece or viewfinder of the practical cameras on set. This allows camerapersons, DPs and ultimately the director to take shots in the virtual world, to frame and compose each shot. It even can allow them to shoot their DLO (Directors Layout) while on set. Similarly, virtual traditional camera controls (Wheels) can be used to allow the manipulation of virtual cameras in the 3D world on set as we capture performers or as an on set post tool just after capturing the performers.