The Digital Design Consortium
Research: Design
Large Area VDE
The Digital Design Consortium (DDC) is a unique collaboration involving participants from two disparate fields: architecture and computer science. It is one of only a few efforts in the academic world to bring together specialists who have backgrounds in both design and information technology. What's more, as a member of the University of Minnesota's Digital Technology Center, the DDC has access to and can leverage the cross-disciplinary expertise of the other Center members including robotics, multimedia and data mining.
One of many research areas at the DDC, the Large Area Virtual Design Environment is a program that explores the effects of being immersed in a wide FOV head mounted display (HMD) on the architectural design process. Does the ability to walk about a design during the design process yield a different outcome than traditional desktop design systems? How does the physical interaction of having one's body in the design space affect the design and the design process? The most recent experiment performed with the system is a test of how distance is perceived through the HMD vs. the real world. Results are to be presented at SIGGRAPH 04 in Los Angeles.
Figure 1 Student working on model (left) in the Large Area Virtual Design Environment and the virtual environment (right) as seen through one eye of the HMD. The kiosk in the right view replaces the traditional menu bar. It follows the user around allowing the user to choose the desired design tool anywhere within the virtual environment.
Description of Equipment:
Figure 2 Trackers are mounted to both the HMD and the triggered interface device.
The HMD we use (figure 2) is an nVisor SX from NVIS Inc. It offers 1280x1024 pixels with a 60° diagonal FOV per eye. The HMD is more bulky than other designs, but its secure "welder's helmet" mount design makes it far more practical for our purposes. The inter-pupilary distance (IPD) and eye-relief adjustments allow the HMD to accommodate a wide variety of users. The HMD also includes a tracker mounting platform on the back. The platform is designed for several standard tracking systems, but ours. So we built a simple adapter plate. There is significant optical distortion (>10%) for which we compensate by pre-distorting the images using texture mapping techniques.
What makes the system "large area" is the HiBall tracker from 3rdTech Inc. This optical tracking system consists of two main components first, the HiBall sensors themselves (figure 3) and secondly, an array of infrared LEDs mounted to the ceiling (figure 4). Each sensor has six optical systems which calculate the centroid of the image of an LED. With enough centroids the system can determine it's absolute location and orientation. Once acquired, the system updates 1 LED at a time maintaining a 1200 Hz update rate for a single HiBall, 600 Hz for two. The ceiling mounted LED array allows tracking anywhere under the array. In our case the total area is 24' x 24' but could be increased by simply adding more LEDs. We find our system is stable to about 2 mm and about 1 arcminute anywhere under the array.
Figure 3 Close-up of the HiBall mounted on the HMD. Each of the lenses is made of RG780 a glass than blocks the visible spectrum but pass the IR.
Figure 4 A section of the ceiling mounted IR LEDs. The system works especially well in rooms with drop celings.