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The virtual camera and its path is shown in the the 3D space of two colliding galaxies. This view is created from a secondary virtual camera inside the CAVE with Thiebaux's Virtual Director renderer. (Image courtesy of Donna Cox, NCSA/UIUC; Bob Patterson, NCSA; Marcus Thiebaux, EVL/UIC; copyright 1996 University of Illinois.) |
Creators of cinematic special effects know that
choreographing the camera's movements through computer
animations requires hours of
laborious keystrokes and clicks and drags of the
mouse. Robert Patterson, Donna Cox, and Marcus
Thiebaux, creators of the camera choreography software
used in making Cosmic Voyage, knew there had to be a
better way.
Their solution was a user friendly yet sophisticated tool called Virtual Director -- conceived and designed by Cox and Patterson, with Thiebaux designing and writing the software program -- that would allow the choreographer to use voice commands and a hand-held wand to control the camera's movements in a 3D stereo environment such as the CAVE.
In choreographing Cosmic Voyage, Patterson used sampled-down versions of the original datasets to achieve real-time responses in the CAVE. An image of the virtual camera and the path it travels in the CAVE is displayed in stereo 3D along with the simulations. "You're actually controlling the position of the camera by moving a wand in 3D space, instead of clicking and dragging the mouse," says Patterson. "It's an intuitive, interactive method of placing camera key frames to build up a spline through space and time."
The spline is a curve containing points that control the direction of that curve. "What's different about this spline," Cox explains, "is that it's a three-dimensional curve. . . . This spline represents the motion of the camera through the dataset, through the CAVE." Each camera point in the spline contains six degrees of freedom -- three for rotation and three for position. Traditional tools required the choreographer to manually create the position of each point. "Ten thousand clicks and drags later, you've got something," says Patterson. "Here you can see everything in a stereo 3D environment. I can move points along the spline to wonderful new positions with the wand, say 'take it,' and voila! In real time the computer refits the spline to the new data points, and I can play back the new camera moves through the dataset."
The output of the camera is displayed on a section of a CAVE wall. Navigation mode provides a free-form method of flying through and around the data, searching for the best perspectives to place camera key frames. In the navigation mode, Patterson uses a hand-held wand to control the viewer's rotation and position with respect to the 3D simulation. "Most programs would give you a simulation on a computer screen and allow you to rotate that simulation on the screen," says Cox. "Here you can actually rotate our immersive environment around that 3D space." Adds Patterson: "It's a great tool for scientific analysis as well as for creating a spline that can document for others what you found."
Patterson and Cox believe Virtual Director could be of great use to the commercial film industry. "People in the production industry could use this to do previsualization of a live action scene for the next day," says Patterson. "Or a director could stand inside the CAVE, direct motion- capture artists outside, and see their digital representations composited into a virtual set."
Go to Cosmological structure formation in the IMAX film Cosmic Voyage.
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NCSA: The National Center for Supercomputing
Applications
access / Summer 1996 issue
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