Real-time rendering of large-scale, forest ecosystems remains a challenging problem, in that important global illumination effects, such as leaf transparency and inter-object light scattering, are difficult to capture, given tight timing constraints and models that typically contain hundreds of millions of primitives. This paper proposes a new lighting model, adapted from a model previously used to light convective clouds and other participating media, together with a distribution of ray processing across multiple GPUs, in order to achieve these global illumination effects while maintaining near real-time performance. The lighting model is based on a lattice-Boltzmann method in which reflectance, transmittance, and absorptance parameters are taken from measurements of real plants. The lighting model is solved as a pre-processing step and requires only seconds on a single GPU. The ray tracing engine uses the wellknown short-stack algorithm, due to Horn, Sugerman, Houston, and Hanrahan. Both the pre-processing step and the ray tracing engine make extensive use of NVIDIA's Compute Unified Device Architecture (CUDA).
Real-time system software is notoriously hard to share and reuse. This paper walks through the methodology and application of ControIShell, a component-based programming system for real-time system software development. ControlShell combines graphical system-building tools, an execution-time configuration manager, a real-time matrix package, and an object name service into an integrated development environment. It targets complex systems that require on-line reconfiguration and strategic control.ControIShell takes advantage of functional object hierarchies to enable code sharing and reuse. It gains flexibility by supporting easy interconnectivity of these objects. It features a unique configuration control system for changing operating modes.The paper concludes by examining the application of this framework to a teleoperated rover under development as a joint effort by NASA, several Russian space research institutes, and US industry. The rover is able to function remotely under control of a virtual reality interface.
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