Modern structured analysis
SIGGRAPH '96 Proceedings of the 23rd annual conference on Computer graphics and interactive techniques
The sciences of the artificial (3rd ed.)
The sciences of the artificial (3rd ed.)
Simulation levels of detail for real-time animation
Proceedings of the conference on Graphics interface '97
Crowd modelling in collaborative virtual environments
VRST '98 Proceedings of the ACM symposium on Virtual reality software and technology
Software engineering of virtual worlds
VRST '98 Proceedings of the ACM symposium on Virtual reality software and technology
Design for presence: a structured approach to virtual reality system design
Presence: Teleoperators and Virtual Environments - Virtual environments: Virtual environments and mobile robots: Control, simulation, and robot pilot training
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For real-time performance, virtual reality systems often employ various performance optimization techniques. One of the most popular methods is using geometric models with different “Levels of Detail (LOD)”. In a previous paper by this author [1], we have proposed to use software engineering principles such as the concept of hierarchical and incremental modeling, and simultaneous consideration of form, function and behavior for modeling VR objects. Each refinement stage driven by such a modeling philosophy produces step-by-step form, function and behavior specifications of a VR object. We can make good use of these by-products as LOD for adaptive display and simulation by additionally specifying conditions for LOD switching. These specifications can be simulated and analyzed in advance for an estimation of performance for a given VR execution environment. Such an engineering process deals with behavior and geometry together; different geometric LOD may possess different behaviors and vice versa. A certain function or behavior might dictate an inclusion of a particular geometric feature that may not be possible to preserve, if the geometric LOD were to created in a bottom-up fashion (e.g. using the mesh simplification algorithms). We demonstrate our approach by modeling an automobile object with three levels of geometric and behavior detail in a top-down manner, simulate their instances in a small virtual town, and based on the simulation result, make predictions to the maximum allowable number of vehicles that will maintain an acceptable frame rate if executed in a faster simulation environment. We believe that our approach combines the idea of hierarchical refinement of virtual objects and the use of LOD in a very natural and intuitive manner.