VRSG as a Computer Image Generator

As an image generator, VRSG supports the features that are typically required for flight training, driving simulations, locomotive simulators, and many other applications.

Core image generation features include:

• Light points
• Light lobes
• Dynamic lighting
• Heads-up display (HUD) and 2D overlays
• Viewports
• Mission functions
• 3D character animation
• Real time MPEG encoding (in version 5.2)

Light points

VRSG supports full-featured light points. Light point processing runs entirely in vertex shader programs downloaded to the graphics chipset, affording exceptional performance. You can expect as much as 20,000 omni-directional light points or 13,000 directional light points per frame at 60 HZ. VRSG light points were developed with input from subject matter experts, such as commercial and military pilots.

Light point features include:

Light lobes

VRSG provides realistic light lobes that yield per-pixel radial attenuation and per-vertex axial attenuation. VRSG light lobes are flexible enough to support landing lights, taxi lights, headlights, and searchlights. You can fully characterize the light lobe radial profile in two dimensions via a texture map. VRSG light lobes do not require multiple database render passes or hardware that can store alpha information in the frame buffer. Instead, VRSG light lobes are rendered single-pass, which affords minimal performance degradation when enabling a light lobe. No drastic impact on fill rate or geometry processing penalties is incurred when enabling light lobes.

Dynamic lighting

VRSG supports a highly optimized dynamic lighting pipeline, which uses per-vertex color, blended with per-polygon material, combined with ambient lighting conditions and directional light sources for efficient and convincing dynamic lighting effects.

Heads-up display (HUD) and 2D overlays

VRSG supports multiple mechanisms for adding 2D overlays to the 3D display. You can describe static overlays in an ASCII file without coding. Static overlays can be made dynamic though a UDP-based interface to the visual system. A simulation host can send commands to the visual system to enable, disable, scale, rotate, and translate overlay primitives.

MetaVR provides a plug-in mechanism for users who want to generate overlay graphics using a low-level graphics API. The end user develops a dynamically loaded library (DLL), which the visual system loads at run time. The visual system makes calls into functions exported by the DLL, which pass the thread of execution to the user-written function. From within the DLL, the user can use Direct3D to render customized overlays.

MetaVR also provides a limited OpenGL emulation layer that allows legacy OpenGL-based HUD implementations to be ported to a VRSG plug-in with ease. This mechanism allowed the Lockheed Martin F-22 HUD originally developed for SGI platforms to be easily ported to VRSG.

Viewports

VRSG supports an unlimited number of viewports per channel. Multiple viewports on a single visual channel may be overlapped or spatially disjoint. Viewports can be horizontally mirrored to support applications that demand this (such as, rear-view mirror), or display systems whose optics imposes a horizontal reversal of the image.

Mission functions

VRSG supports the basic mission functions requirements to meet the needs of ground -based vehicle simulators up to fast moving fixed-wing aircraft. VRSG channels support one laser range per channel, per frame at 60 HZ, with single frame latency. VRSG also supports an Above Ground Level (AGL) response per channel at 60 HZ. A library that can be integrated into the simulation host provides for features such as point-to-point intervisibility, terrain height lookup, and collision detection with terrain or dynamic model geometry.