"From such small beginnings -a mere grain of dust, as it were -do mighty trees take their rise."Henry David Thoreau from "Faith in a Seed" ABSTRACTRecent advances in computer graphics have produced images approaching the elusive goal of photorealism. Since many natural objects are so complex and detailed, they are often not rendered with convincing fidelity due to the difficulties in succinctly defining and efficiently rendering their geometry. With the increased demand of future simulation and virtual reality applications, the production of realistic natural-looking background objects will become increasingly more important. We present a model to create and render trees. Our emphasis is on the overall geometrical structure of the tree and not a strict adherence to botanical principles. Since the model must be utilized by general users, it does not require any knowledge beyond the principles of basic geometry. We also explain a method to seamlessly degrade the tree geometry at long ranges to optimize the drawing of large quantities of trees in forested areas.

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Automated aerial surveillance and detection of hostile ground events, and the tracking of the perpetrators have become of critical importance in the prevention and control of insurgent uprisings and the global war on terror. Yet a basic understanding of the limitations of sensor system coverage as a function of aerial platform position and attitude is often unavailable to program managers and system administrators.In an effort to better understand this problem we present some of the design tradeoffs for two applications: 1) a 360° viewing focal-plane array sensor system modeled for low altitude aerostat applications, and 2) a fixed diameter area of constant surveillance modeled for high altitude fixed wing aircraft applications. Ground coverage requirement tradeoffs include the number of sensors, sensor footprint geometry, footprint coverage variability as a function of platform position and attitude, and ground surface modeling. Event location specification includes latitude, longitude, altitude for the pixel centroid and corners, and line-of-sight centroid range.