A system to measure, control and minimize end-to-end head tracking latency in immersive simulations

System latency (time delay) and its visible consequences are fundamental Virtual Environment (VE) deficiencies that can hamper user perception and performance. This paper presents an immersive simulation system which improves upon current latency measurement and minimization techniques. Hardware used for latency measurements and minimization is assembled based on low-cost and portable equipment, most of them commonly found in an academic facility without reduction in accuracy of measurements. A custom-made mechanism of measuring and minimizing end-to-end head tracking latency in an immersive VE is assembled. The mechanism is based on an oscilloscope comparing two signals. One is generated due to the head-tracker movement by a shaft encoder attached on a servo motor moving the tracker. The other signal is generated by the visual consequences of this movement in the VE using a photodiode attached to the computer monitor. Visualization and application-level control of latency in the VE was implemented using the XVR platform. Minimization processes resulted in almost 50% reduction of initial measured latency. The description of the mechanism by which VE latency is measured and minimized will be essential to guide system countermeasures such as predictive compensation.

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