Design and configuration of the DIVE computer.

The LONI is moving to a new facilities mid-summer 2005. That new facility include a IMAX-like theater. This multi-million dollars equipement is built on an audio-video-data routing system, incorporating computers, SD Video and HDTV, and teleconferencing sources in one unified interface. One of my jobs at the LONI was to design and configure the PC and Apple computers to be included as visualization tools.

Windows XP on a 3240x1024 screen. Center : 720p HDTV movie, right : DVD player insert.

Objectives of the project

The visualization equipement has a 20 meters wide curved screen who's illuminated by three DLP projectors. [dive floorplan, projectors]. Our objectives were :

1. Drive three projectors
2. Do active stereoscopy
3. Use commodity hardware and operating system
4. Runs existing scientific visualization software without modifications

Possible solutions

When the visualization room was designed, there used to be three ways to use them. You could use

• A mainframe computer, most likely an SGI mamoth, who has a group of graphic cards, each card taking care of a projector
• A bunch of PC running as a visualization cluster, most likely running Linux and a Virtual Reality software suite.
• A single PC, using only one third of the screen width.

The LONI is a major SGI client, with two realy big computers [reed datacenter picture] and a couple of dozen of SGI workstations. Thoses supercomputers are aging and needed to be updated or replaced.

Selected solution :

We're using a dual CPU / Dual GPU PC based on Nvidia NForce Pro chipset with a couple of Opterons 252 and two PNY Quadro FX4400 graphic cards. This solution have been somewhat troublesome to run, for we were month in advance on the Nvidia release date of such a solution. I figured out that settings at the siggraph 2004 and the drivers were released at the siggraph 2005.

The trouble :

We had lot of trouble get the two Quadro do all the functions we needed :

• Hardware-accelerated OpenGL rendering across the two cards
• Overlap arreas accross the two cards
• Accurate pixel-clock tweaking to use the projectors in stereoscopy

As of today, we're able to feed the full screen under XP and Linux. The active stereo works only on 2/3 of the screen and Nvidia claim that the Multihead-SLI driver, allong with the GSync daughter boards solves theses issues. Stay tuned.

The future :

The expantions of our current hardware system, on the road to a PC supercomputerwill likely include

• Dual / Quad cores processors
• Quad / Octo processors motherboards
• Dual GPU graphic cards