Information Technology Reference
In-Depth Information
A variety of different graphic displays and input devices can be used with the
DIVERSE graphics interface by the use of separately compiled and loaded Dy-
namic Software Objects (DSOs). By plugging in one of many DSOs for graphics
display, for example, the same visualization programs can be used on desktop,
laptop, or full three-dimensional immersive systems.
Individual DSOs are also used to add new functionality to our visualization
software system. Our group has developed a wide range of DSOs that allow a
user to interact with the objects he or she is viewing. This includes functionality
to move objects around, select individual objects or sets of objects and assign
functionality to the selected objects, interact with outside software programs,
bring data into the system, send data out of the system, and load or unload
objects during a visualization.
Individual DSOs can be loaded to add simple functionality to a scenegraph,
such as adding a particular light source or an object to represent a pointer for
the user to select objects. Our wandPointer DSO for example, is loaded with
the objectMover DSO, as shown in Fig. 7, to allow a user to select an object
and then move it with the movement of the wand.
Fig. 7. Demonstration of the objectMover and wandPointer DSOs.
Another set of DSOs that allow a user to take a look inside an object is
particularly useful for viewing large sets of volume data. Figure 8 below demon-
strates the clipWand DSO. Through the use of shared memory, a user can enter
shell script commands to an accompanying program, hev-clipwand , to specify
up to 6 different clipping planes that are defined with respect to the direction
and position of the wand. The wand is a hand-held device and its position is
continually tracked by this system. This enables the user to interactively po-
sition the clipping planes in real time in order to reveal the interior detail of
three-dimensional data sets. These clipping planes can be turned on and off in-
teractively during a visualization. Volume data can also be manipulated with
DSOs that edit lookup tables, making only objects within certain color ranges
visible, for example.
ADSOknownas objSwitchExec has evolved to give functionality to the
objects of a scenegraph. When selected, an object can be assigned the function
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