Case Study: Digital Domain (Titanic)

1. Case Study: Digital Domain (Titanic) • The Company: Digital Domain (One of the founder: James Cameron) • Digital Domain is an advanced full-service production studio located in Venice, California. There, we generate visual effects for feature films and commercials as well as new media applications. Our feature film credits include Interview with the Vampire, True Lies, Apollo 13, Dante's Peak and The Fifth Element. (see http://www.d2.com/). [1] [1] D. Strauss, "Linux Helps Bring Titanic to Life", Linux Journal, 2/98, www.ssc.com/lj/issue46/2494.html

2. The Task • Since building a full-scale model of the Titanic would have been prohibitively expensive, only a portion of the ship was built full size (by the production staff), and miniatures were used for the rest of the scenes. • To this model we added other elements of the scene such as the ocean, people, birds, smoke and other details that make the model appear to be docked, sailing or sunk in the ocean. • To this end, we built a 3D model and photographed 2D elements to simulate underwater, airborne and land-based photography. • For many digital effects shots, original photographic images are first shot on film (using conventional cinematic methods) and then scanned into the computer. • Each frame of film is stored as a separate file on a central file server. • A digital artist then begins working on the shot. The work may involve creating whole new elements such as animating and rendering 3D models or modifying existing elements such as painting out a wire or isolating the areas of interest in the original film.

3. The Task (continue) • This work is done at the artist's desktop (often on an SGI or NT workstation). During this step the individual elements are color corrected to match the original photography, spatially coordinated and layered to create the final image. • Once the setup for this work is done, the process is repeated for each frame of the shot. This batch processing is done on all the available CPUs in the facility, often in parallel and requires a distributed file system and uniform data overview. • Finally, once all the elements are created, the final image is "composited” throughout the facility. • During the work on Titanic the facility had approximately 350 SGI CPUs, 200 DEC Alpha CPUs and 5 terabytes of disk all connected by a 100Mbps or faster network.

4. The Analysis & Implementation • The digital artists require certain packages that relied on special high-end (often 3D) hardware acceleration (only available on SGI platform) • Therefore, the setup phase is still on SGI Workstations. • For the batch processing phase, the processor pool model can help. • Which OS? Digital UNIX, Windows/NT, or Linux? • Digital UNIX: cost, no device drivers, cannot talk to NT server, and lack of flexibility. • Windows/NT: no auto-mount, NFS, or symbolic links. • Linux: free, device driver available, and source code but no technical support • The Choice: • 160 X 433 MHz DEC Alpha (Alpha is two times faster than Intel in float) • 55 running Windows/NT, and 105 running RedHat Linux 4.1 • 160 machines connected by SMC 100Mbps FastEthernet • NCR 810 SCSI card for local hard disk.

5. The Look and Performance • Two weeks to set up the room • Electricity, 10 rack mounts, 100+ network connections, and the switching system of the screen, mouse, and keyboard. • Start up scripts for system names, IP address, and some system maintenance programs. • First job: simulate and render the water elements -- computation intensive. About 45 minutes (3.5 times faster than the old SGI systems) • Second job: composing frames -- I/O intensive, each machine had to read elements from disks on servers spread around the facility and combine them into frames to be stored centrally. About 2 times faster than the old SGI systems. Runs from June to end of August, 24 hours a day and 7 days a week