MetaVR Physics-Based IR

MetaVR’s physics-based IR component of Virtual Reality Scene Generator™ (VRSG™) version 5, enables computer image generators (CIGs) to render a physics-based simulated infra-red (IR) real-time scene. An external application is used to generate a radiance profile for all database materials over a 24-hour period. The user inputs environmental data over time for a full 24-hour diurnal cycle, using user-defined time intervals. The application then pre-computes in batch mode a radiance profile database that is accessible by VRSG at runtime. Given material type and time-of-day, VRSG is able to extract the directional and ambient radiance from the database and compute the display intensity as a function of sun-angle, sensor dynamic range, and atmospheric propagation.

VRSG sensor-based simulated Predator UAV image of a scenario featuring activity on MetaVR's virtual Afghanistan terrain. The scene shows a herd of donkeys with herdsmen, two characters digging under the trees, and a vehicle on the road. The entities and cultural features are from MetaVR's 3D content libraries. The image is taken from a 10-minute scenario running in Battlespace Simulations' Modern Air Combat Environment (MACE), which uses VRSG for its visuals. Image courtesy of Battlespace Simulations.

MetaVR provides the radiance profile generation application at no extra charge. This application, however, is built upon a 3rd-party API called RealIR from Technology Service Corporation (TSC).  A run-time license is required for RealIR from TSC. The run-time license enables the radiance profile generation application to run on the licensed computer.  A Real IR license is also required for any IG channel needing real-time access to the radiance profile database.  Contact TSC for pricing and exportability.

	View of insurgents loading mortar at a tunnel entrance on MetaVR's Afghanistan 3D terrain rendered in VRSG. The image on the right is simulated UAV camera thermal mode, which shows some heat at the location of the mortar.

The radiance profile generation application computes the ambient and directional radiance for all possible materials in the RealIR material library. The computation of atmospheric attenuation and mapping of radiance to sensor dynamic range is performed in real-time by the IG.  This allows sensor dynamic range (level and gain) to dynamically change in real-time on a given radiance profile database. Real-time changes to atmospheric conditions that affect radiance propagation are also possible in real-time, as the atmospheric propagation model is deferred to the IG for real-time computation.

Material codes are associated with the visual database through a texture to material mapping file. With this file users can associate material codes used by the IR model with texture names. This scheme enables new content to be added to the visual database and moving model libraries without invalidating existing radiance profile databases.

Infra-red view of a humvee model from the MetaVR 3D vehicle library (on the left) beside an infra-red photograph of an actual humvee vehicle. The photograph of the real humvee vehicle is taken from PEO-STRI's poster of the Recognition of Combat Vehicles (ROC-V) Program, which has been displayed at trade shows. The photograph is used here as a backgound image in the MetaVR Model Viewer. In the upper right is the textured view of the humvee model.

VRSG’s physics-based IR benefits

VRSG's database-oriented approach to physics-based IR has several benefits over real-time physics models:

IR modeling overhead is per-computed off-line for the entire 24-hour diurnal cycle. This allows the IG channels to run at comparable frame rates to that of a normal visual spectrum scene. The physics model is not burdened with the rendering of the IR scenes, thus it can use a much higher fidelity model than what would be possible if the IR modeling took place in real-time on the same computer that is rendering the IR scene. Configuration management is simplified for site personnel, as the radiance profile database can be generated off-site by a subject matter expert, and exported to remote IG channels. The radiance profile database contains data for all possible materials, allowing the database and model content to grow without invalidating the radiance profile database. The IG can instantly change time-of-day to any time in the 24-hour cycle.

This image shows MetaVR's physics-based IR used in ZedaSoft's virtual cockpit application for Lockheed Martin's F-16 simulator. Image courtesy of ZedaSoft, Inc.

A 24-hour cycle IR view from VRSG in increments of 1 hour starting at 12:00 midnight.