FIGURE 2. Workstation screen with URLViewer driving Mosaic Using this technique of surrogate travel, the user is presented with a completely separate application. This application "drives" Mosaic via remote control. The principle advantage is that the user is able to manipulate a 3D environment in real time using all of the resources and performance of the graphics workstation, independent of the network bandwidth. The disadvantage is the loose coupling of the separate application with Mosaic and the need for a separate user interface.
FIGURE 2. Workstation screen with URLViewer driving Mosaic
FIGURE 3. External application (URLScene) controlling Mosaic
The existing test application is a modification of the SceneViewer, Inventor application provided by Silicon Graphics [Inventor]. The SceneViewer program was modified to interpret object labels which are URLs. The URL is sent to a script which generate the appropriate UNIX signal causing Mosaic to go to the URL in the label. Following is a fragment of the Inventor file for the house containing a URL:
Separator {
Label {
label "http://nemo.ncsl.nist.gov/~sressler/OVRThome.html"
}
ShapeHints {
hints (SOLID | ORDERED | CONVEX)
creaseAngle 0.6
}
This method of control requires the ability of Mosaic to respond to a SIGNAL generated from an external process. NCSA Mosaic for the X Window System provides this feature and is documented at NCSA [Remote].