A framework for real-time rendering in virtual reality

Virtual Reality applications must maintain a constant, frame rate to maximize user performance and comfort. The display component of a VR application consumes a significant portion of the available time, therefore controlling its time usage solves a significant portion of the time management problem. This paper addresses the problem of producing the best possible display given a time budget. This problem has often been called time critical rendering, and numerous solutions have been proposed in the past. Our solution differs from previous ones in that it is based on a general framework for time critical rendering. This framework has two key components; a model for predicting the time required to display an object based on its current graphical representation, and a graphical compiler that converts object geometry into efficient graphical representations. In addition to guaranteeing a fixed frame rate, this approach requires minimal designer effort, and can be used on a wide range of platforms without modifying the models or application.

This paper concentrates on the general framework and the techniques for predicting object display time. A companion paper describes one of the techniques that we are using to decreasing rendering time [Isler1996].