AuSIM3D Vectsonic for CAVEs

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AuSIM3D Vectsonic for CAVE's
3D Loudspeaker Array System

Vector-Based Amplitude Panning (VBAP) was created specifically to display an immersive, untethered auditory display for Cave Automatic Virtual Environments (CAVE's). AuSIM's Vectsonic loudspeaker technology supports VBAP loudspeaker-mappings. And thus AuSIM3D Vectsonic is a viable sound solution for CAVE's.

CAVE's are visual virtual environment display systems created from three or more enveloping wall-sized projected images. Typically cube-shaped, with rear-projections so the projections do not cast a shadow, CAVE's consume large facilities.

The designs presented here assume a five-sided CAVE with non-folded rear-projection and sound-transmissive projection screens. Satellite loudspeakers are placed outside of the projection frustrums so as not to cast a shadow. These designs do not account for structure to support the satellites.

Digital multi-channel audio systems are often built and expanded in blocks of 8-channels. Any number of channels can be designed, but typically the next modulus of 8 must be included even if unused.

The designs shown below all assume 4 subwoofers (not shown) and a number of satellite loudspeakers to bring the total channel count to a multiple of 8. These designs are all symmetrical. However, Vectsonic does not require symmetry.


16 Channels, 12 Satellites, 4 Subwoofers		Click on an image to enlarge
Perspective	Top View	Side View
24 Channels, 20 Satellites, 4 Subwoofers
Perspective	Top View	Side View
32 Channels, 28 Satellites, 4 Subwoofers
Perspective	Top View	Side View

A Note About Perceptual Accuracy and CAVE's

CAVE's were probably developed with two primary goals: displaying a virtual environment without encumberance as opposed to the head-mounted display (HMD), and creating an environment that could be readily shared between two or more users. If CAVE's display near-field objects, they fail on both of these goals. Motion-parallax is the primary perceptual mechanism for a user's sense of immersion within local objects. The static secondary perceptual cue often employed is stereo parallax. While it is technically feasible to present independent displays for each eye of multiple users, accommodating more than one user for either motion-parallax or stereo-parallax is very uncommon. Further, it is only recent that tracking systems are commonly unencumbered or even untethered.

The practical response to these issues is to most often present CAVE virtual environments to multiple participants without position correction. The result is that the perspective is always distorted.

A VBAP sound display is a similar compromise. Precise audio systems control amplitude, phase, spectral coloration, and reverberation of sound. VBAP controls only amplitude. It is possible to create a precisely accurate sound environment to one or more users without encumberance, but the expense limits the practicality. Thus CAVE's and VBAP are well-matched for their benefits and compromise.

A Note About Vanilla VBAP vs. AuSIM3D Vectsonic
Why would one choose AuSIM3D Vectsonic over open-source VBAP?

Complete Propagation Simulation
The detail in AuSIM3D's sound simulation engine is without parallel. VBAP gives you the final display mapping for a sound positioned in 3D relative to the users, but it does not simulate the propagation of the sound from its origin to the loudspeaker positions. VBAP replaces binaural HRTF's, but HRTF's are only a small part of realistic sound simulation.
Enhanced Implementation of VBAP
AuSIM's significantly emhances its implementation of VBAP. AuSIM3D Vectsonic supports
- a mixture of loudspeaker types
- looming sources
- optional vector-based correction for phase, spectral coloration, and reverberation
- head-tracked loudspeaker display

Mixed Binaural/Loudspeaker Display
AuSIM3D supports a mixed environment of Vectsonic loudspeaker and binaural headphone displays. This feature is analogous to the principal (active) participant in the CAVE being head-tracked and thus having perspective-correct image generation for his/her specific point of view. All passive participants observe images that update to the active participant's movement and observe a slightly distorted perspective. If the active participant wears a wireless headset, a binaural AuSIM3D display can be generated for their specific point of view, while the passive participants hear the Vectsonic display.

More Vectsonic: Overview — Software — Installations — CAVE's

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