Temporal Links: Recording and Replaying Virtual Environments

Abstract

Virtual reality currently lacks the kinds of sophisticated production technologies that are commonly available for established media such as video and audio. This paper introduces the idea of temporal links, which provide a flexible mechanism for replaying past or recent recordings of virtual environments within other real-time virtual environments. Their flexibility arises from a combination of temporal, spatial and presentational properties. Temporal properties determine the relationship between time in a live environment and time in a recording, including the apparent speed and direction of replay. Spatial properties determine the spatial relationship between the environment and the recording. Presentational properties determine the appearance of the recording within the environment. These properties may be fixed, dynamically varied by an application, or directly controlled in real-time by users. Consequently, temporal links have a wide variety of potential uses, including supporting post-production tools for virtual environments, post-exercise debriefing in training simulators, and asynchronous communication such as virtual reality (VR) email, as well as providing new forms of content for virtual worlds that refer to past activity. We define temporal links and their properties and describe their implementation in the MASSIVE-3 Collaborative Virtual Environment (CVE) system, focusing on the underlying record and replay mechanisms. We also demonstrate applications for adding new content to an existing virtual world, and a VR post-production editor. Keywords Collaborative virtual environments, temporal properties, recording and editing techniques, post-production technologies. 1