The Earth Theater:
The Earth Theater at the Carnegie Museum of Natural History is a Panoromic SkyVision Theater, a product of SkySkan, Inc. The theater has a 40 foot diameter, a 210 degree horizontal viewing angle, a 30 degree vertical viewing angle, and seats an audience of 68. The theater's five digital light projectors, slide projectors, lighting instuments, and 4.1 channel surround sound are driven by SkySkan's Spice Multimedia Control System. The SkyVision system was specifically designed for the playback of pre-rendered full-dome & panoromic digital video.

ETC System Diagram
Click to view		 ETC Panoromic Real-time Interaction System:
The Entertainment Technology Center's system consists of two off-the-shelf 866Mhz Intel Pentium III Computers: one for serial communication with Spice and rendering graphics to all five projectors, and a second for sound playback and interactive inputs. The rendering computer employs five ATI Radeon video cards on the PCI bus. The sound/interaction computer uses a Creative Labs Sound Blaster Live! card in order to create three-dimensional spatialized audio. Audience interaction is done through an active infra-red camera, coupled with an ImageNation PXC200 frame grabber, and an omni-directional microphone plugged into the SoundBlaster card.

The main software used on the project is Alice, a 3D authoring environment developed by the Stage3 Research Group at Carnegie Mellon University. Alice is designed for the rapid prototyping and development of interactive 3D graphics. Alice was intended to be used for material created for desktop computer and Head-Mounted display use. The ETC Team and Stage3 collaborated to adapt Alice for playback across multiple displays by having each camera object in the virtual environment output to a separate video card.

In order to create a seamless view across the five projected images, the ETC Team employed an alpha-channel gradient within the virtual world. This created issues where one camera could see another camera's blending object, so the visibility of the blending object was tied to the refresh rate of the projectors.

Since such an immense computational load was placed on a single computer, audio playback and processing of audio and video interations were outsourced to a separate machine. The remote sound and vision server programs were written by the students on the project.