3 Features

CAVEview achieves interactivity by executing the application locally on the Mosaic user's machine. Instead of a large image file, an application object file and required resource files are transferred. Therefore, download time is decreased since animation files are typically larger than application object files. Since the application is executed locally, the graphics are created real- time as the user selects a path through the data. Similarly, the user can interactively change the size of the graphics window and explore the scene without time limitation or extra loading time. CAVEview allows each user to explore and collect information on the science they are viewing at their own pace.

3.1 CAVEview as a Presentation Tool

Figure 4: The Graphics Window

The CAVE Simulator was designed as a development tool where input commands are given to the CAVE Simulator through the keyboard. CAVEview is designed as a presentation and viewing tool, consequently, there had to be a user interface that would allow the CAVE novice to quickly and easily move about the data and the CAVE space. The CAVEview interface allows the user to interact with objects in 3D as they might in the actual CAVE. CAVEview has all the functionality of the CAVE Simulator environment with the additional enhancement of script record and playback features Use of the Logitech tracking system and stereo glasses, provides the option of stereo viewing and enhanced object manipulation.

3.2 CAVE Movement and Viewpoint

Figure 3: The Control Panel

There are three areas for user input within CAVEview, the control panel, the graphics window and the scripts panel. The control panel, shown in figure 3, consists of Motif widgets that control navigation, perspective, wand input, and available visual cues for the CAVE. CAVEview maintains CAVE Simulator features such as an outline of the CAVE structure, a virtual CAVE person, and a wand.(See figure 2.). There are widgets for moving the virtual CAVE person around the CAVE space and tilt controls for the virtual persons' head and wand. There are three viewing modes wall, perspective, and outside view. [2] Head tilt controls are used in the perspective and outside view modes and wand orientation controls are available in all view modes.

3.3 Stereo, Tracking and the Flying Mouse

The mouse, tracking and stereo viewing are features that add realism to the simulated CAVE experience. The operation of the wand buttons change depending on the application. Typical operations for these buttons are fly through capabilities, data manipulations, and menu selections. [4] The Mosaic documentation, that accompanies each CAVEview application, should describe the operation for each of the buttons.

In order to make user interaction with the applications more natural, tracking and three dimensional input capabilities were added. Use of these features, requires a magnetic tracking device and a three dimensional mouse such as the Logitech 3D mouse. When the user is equipped with a head tracking system, CAVEview calculates the scene in viewer-centered perspective. In other words, the computer generates the image based on the users distance from the screen, interoccular distance, and head orientation. The three dimensional mouse represents the wand in the CAVE: the user has direct control of each of the size degrees of freedom. In the CAVE, the wand can be moved up and down, left and right, forward and backwards, as well as azimuth, elevation, and roll, the three orientation controls. It is very difficult to represent these six degrees of freedom with a two dimensional input device like the traditional mouse. These 3D input features create a physical relationship between the way the user moves and what he sees.

3.4 Audio

The CAVE currently uses a sound server called vss[6] to create sounds for the virtual reality applications. Most of the CAVE applications use this server to play sounds created by frequency modulation, additive synthesis, digital sampling, and MIDI. Likewise, the sound server can be run while using CAVEview, consequently the CAVEview user experiences the same audio feedback as they would in the CAVE.

3.5 Scripts

Scripts are the record and playback feature available in CAVEview. They offer an animation- like experience without a frame by frame playback. Pre-recorded scripts provide a suggested path for user exploration and playback. Both the user and application developer can record a script or multiple scripts through the Scripts Control Panel, shown in figure 4. The script file contains the widget, keyboard, and mouse presses which specify a path or data manipulation. The script file is then saved in the user specified directory or packaged within the application object file. Scripts designed by the developer are automatically loaded when the application is started in CAVEview. The user can insert their own scripts to be loaded upon start up by changing a resource file.

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