The Distributed Simulation Internet (DSI) provides users access to large-scale, complex, active, unpredictable virtual environments. If users are to effectively use these environments, they will require support for understanding and acting in these environments. Support is necessary because humans have a time and space limited span of attention. The Satellite Modeler, Omniview true 3D, and Synthetic BattleBridge projects were undertaken to develop and investigate the interfaces and autonomous agents required to effectively support users of the Distributed Simulation Internet. The Satellite Modeler emulates the near-Earth space environment and portrays models of satellites moving in their correct orbits around the Earth. The motion of the satellites is broadcast to users of the DSI. The Satellite Modeler is intended to function as a training and operational aid for orbital analysts and to help them understand key spatial relationships for satellites in near-Earth orbit. The Omniview project was undertaken to provide interactive control and manipulation of a true 3D image and to thereby assist the user in understanding the activity within the DSI-hosted virtual environment. That project developed an interface that provides the Omniview user with the ease of use that a window, icon, mouse, and pointer GUI interface provides to users of 2D displays. The Synthetic BattleBridge is a system that, like the Omniview, portrays a DSI-hosted virtual environment but does not act in it. The Synthetic BattleBridge is designed to support users in making accurate and timely decisions by providing several different types of cognitive support for understanding and analyzing the activity in a battlespace. In this paper, we briefly describe each project and present some observations and conclusions we have drawn based on our experience with them.

As virtual environments grow in complexity, size, and scope users will be increasingly challenged in assessing the situation in them. This will occur because of the difficulty in determining where to focus attention and in assimilating and assessing the information as it floods in. One technique for providing this type of assistance is to provide the user with a first-person, immersive, synthetic environment observation post, an observatory, that permits unobtrusive observation of the environment without interfering with the activity in the environment. However, for large, complex synthetic environments this type of support is not sufficient because the mere portrayal of raw, unanalyzed data about the objects in the virtual space can overwhelm the user with information. To address this problem, which exists in both real and virtual environments, we are investigating the forms of situation awareness assistance needed by users of large-scale virtual environments and the ways in which a virtual environment can be used to improve situation awareness of real-world environments. A technique that we have developed is to allow a user to place analysis modules throughout the virtual environment. Each module provides summary information concerning the importance of the activity in its portion of the virtual environment to the user. Our prototype system, called the Sentinel, is embedded within a virtual environment observatory and provides situation awareness assistance for users within a large virtual environment.