System lag tests for augmented and virtual environments

Abstract

We describe a simple technique for accurately calibrating the temporal lag in augmented and virtual environments within the Enhanced Virtual Hand Lab (EVHL), a collection of hardware and software to support research on goal-directed human hand motion. Lag is the sum of various delays in the data pipeline associated with sensing, processing, and displaying information from the physical world to produce an augmented or virtual world. Our main calibration technique uses a modified phonograph turntable to provide easily tracked periodic motion, reminiscent of the pendulum-based calibration technique of Liang, Shaw and Green. Measurements show a three-frame (50 ms) lag for the EVHL. A second technique, which uses a specialized analog sensor that is part of the EVHL, provides a "closed loop" calibration capable of sub-frame accuracy. Knowing the lag to sub-frame accuracy enables a predictive tracking scheme to compensate for the end-toend lag in the data pipeline. We describe both techniques and the EVHL environment in which they are used.

Influence of visual and haptic delays on stiffness perception in augmented reality

“…Some methods for measuring delays have been discussed, e.g. in [10,12]. Nevertheless, our interest not only lied in the achieved endto-end latency, but also in the contribution of individual steps in the pipeline.…”

Reaching movements to augmented and graphic objects in virtual environments

“…A twosensor OPTOTRAK 3020 motion analysis system (Northern Digital, Inc.) tracked the three dimensional position of the IREDs on the goggles at a sampling rate of 240 Hz. This information was processed by the SGI ONYX2, with a 20-40 ms lag, to provide the subject with a real time, head-coupled view of the image [19]. Finally, three IREDs were positioned on the subject's thumb, index finger and wrist such the 3-D position coordinates of the movement of these landmarks could be tracked and stored for later analysis.…”

Characterizing Latency in Touch and Button-Equipped Interactive Systems

“…Until recently, its measure has been a tedious process based on the use of external cameras [11,14,15,[18][19][20][21] but methods have been proposed to ease the process through interactive tools [2,6] or repeated measures [3,7]. These tools can be used to try to reduce latency but it can be a trial and error process without the understanding of the influence of each part of a system.…”