Summaries for week 2
Merging Virtual Objects with the Real World: Seeing Ultrasound Imagery within the Patient
This study presents a 3D ultrasound visualization technique to acquire and render real-time ultrasound data and create a virtual environment based on that.
When the ultrasound scanner took an echography image, the position and orientation of the image and also the head mounted display were tracked. Then an image-generation system generated a 3D rendering of the ultrasound image mixed with real world image. This real world images were captured by head mounted TV cameras and it was combined with synthesis images through a video see-through system.
A “transducer transformation” and a “camera transformation” were used to calibrate the system. The first transformation, transducer transformation was to tune 2D ultrasound image with the ultrasound transducer. Similarly, camera transformation was used to calibrate the HMD TV camera position with trackers on the head-mounted Polhemus.
An experiment was conducted to scan the abdomen of a live pregnant woman and, as a result, different technical problems were found. First, the overlaying image did not appear to be inside the body and the virtual hole in the subject could not fix it because the pit hided everything in the real image. Second, there was a lag between image generation and tracking that could be fixed by delaying the live video image to matches that of the synthesis images. Third problem was the tracking system range and stability due to hardware limitation. The two last problems, Head-mounted display system resolution and more powerful display engines, were more related to hardware limitation as well.
Virtual Environments for Treating the Fear of Heights
This paper designed and developed a virtual environment to be used for acrophobia treatment using behavioral therapy. The behavioral therapy is an exposure based method in which the therapist measures how long the client can tolerate an anxiety-inducing stimulus.
An elevator, a series of balconies, and a series of bridges, were used to design the virtual environment. The elevator was modeled as an open elevator located inside of a 49-story building. It was built with actual wooden platform to provide patients with a greater sense of reality. The outside balconies were attached to the building at different heights. Similarly, the canyon had bridges with different heights, made of virtual wood and rope.
An experiment has conducted with 17 participants during seven weeks. The results show that most subjects became immersed in the virtual environment. The participants’ subjective units of discomfort were mostly improved by attending the weekly 35- to 45-minute sessions. In addition, the recorded number and type of physical anxiety such as loss of balance or light-headedness, heart palpitations, restlessness or pacing, tremors or shakiness, feeling “nervous” or “scared,” weakness in the knees, tightness in the chest, and feeling “tense” showed that the subjects were immersed by the virtual environment.
Designing Interactive Theme Park Rides
This paper explains some challenges and solutions on how to design an interactive theme park ride.
The design of the interactive ride was a trade off between the user control and intuitive adventure. Pirates of the Caribbean—Battle for the Buccaneer Gold was designed in such a way that it gave a full control to users to operate the ship. However, the path of the adventure was controlled using different techniques to avoid going to dull places such as using guide ship, snake attack, and waterspout.
An intuitive user interface was designed to ensure the interactivity of the theme park rides. A simple physical interface like a steering wheel and real cannons were used to increase the sense of reality while some features like featuring light blue cannonballs, changing the cannonball physics, and developing enemies with rules used to twist the reality and make the game more intuitive.
A motion base and 3D localized sound were used to provide users with the sense that any the movement they make or any reactions their surrounding environment has is real. The motion base simulated the movement of wave and every cannonball hit while the 3D sound tactile speakers created the soundbed of crews and boat creaks underfoot.
Guest testing was conducted to ensure the cannon parameters, difficulty settings, and general developments of the game logic are optimized.
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