Vipul – Week 2 Summary : Heights. Scan. Action.

Virtual Environments for Treating the Fear of Heights
Hodges, L., Barbara Rothbaum, Rob Kooper, Dan Opdyke, Tom Meyer, Max North, Johannes de Graaff, & James Williford

This was an experiment to use VR to treat Acrophobia – Fear of Heights using the method of Graded Exposure by taking the patient ‘out into the real world’ without having to take the patient really out into the real world. They replicated scenarios of a balcony, elevator and a bridge, slowly increasing levels. For the display, I agree with the decision to go with the monoscopic display since to be able to tackle the fear of heights for people, it is necessary to make them believe they are ‘there’, thus the feeling of presence is essential. The level of detail enabled with the monoscopic display is a good trade off.
The observation that the level of anxiety for people kept increasing for people as the level (height of bridge) kept increasing proved that the ‘reality’ afforded by the system was believable. Also, repeated turns reduced their level of anxiety, which proves that the strategy worked. However, something that could be a reason is that at the back of the mind people know that this is a staged setup. The first attempt, just because of the harsh newness of the setup, people feel anxious. On the next attempts the feeling that they ‘can’t fall, after all’ might kick in, which may disprove the result. However, the experiment may definitely be a cheaper alternative to actually taking the patient to a real scenario and more effective than systematic desensitization.

Merging virtual objects with the real world: seeing ultrasound imagery within the patient.
Bajura, M., Henry Fuchs, Ryutarou Ohbuchi (1992).

This is an old paper which tries to overlay the ultrasound display in 3D over the mother in real time when the doctor is performing the ultrasound. The main technical problem that the paper deals about is being able to generate a true 3D representation since such a technology was not available yet. The method considered was to take spatial 2D slices and piece them together into a 3D volumetric display. One idea was a conventional 2D sector scanhead with an annular array transducer is rotated by a stepper motor to get a third scanning dimension.

Another big issue to tackle was being able to utilize this acquired data and being able to display it in real time with minimal lag. A feedback of the system mentioned the swimming of the scene as a problem. An interesting observation was the the AR display seemed more plastered on to the surface than appearing to be a 3D hollow into the surface. They tried an alternative of creating a hollow surface, but another idea could be using a little depth shadow effect which gives u a feeling of going just within the skin, and not creating a hollow altogether.
As noted, this technology, on improvement has been useful in architectural scenarios where people could visualize a structure and other surgical operations.

Designing interactive theme park rides.
Schell, Jesse and Joe Shochet.

In this paper, entertainment was given more importance than realism to generate the sense of immersion for the users. There were many places where the acceptable laws were broken like a blue canyon ball and the ship moving at 90mph , but since the developers were working on the premise of a movie gave them the flexibility to ‘bend some rules’ and still make it believable and immersive.
The images of the setup looked impressive where they created a life size model of a ship with immersive sound, contextual vibrations of the ship when a canon hits and many small things which made it interesting. It was interesting to read the techniques they used to direct the sailors to move towards the islands where all the activity was. Another interesting ploy was the climactic ending which had a more immersive experience in the scenario when the players lost compared to when the players won, in which case they are euphoric regardless. Thus this paper was interesting as a study of a combination of VR and storytelling.

Hitesh – week 2 summary

Designing Interactive Theme Park Rides

The paper highlights the design, motivation and the relevant elements of virtual reality for an Interactive theme park game based on the concept of Pirates of the Caribbean.  The game is targeted for a group of 4 users taking into account the usual user group of such theme parks.

The players steer a ship and lodge cannonballs on other ships and monsters during their odyssey on high seas, in quest for gold. The aim is to provide a close simulation to a pirate ship setting through not only visual but surround sound and motion effects. Attention has been paid to specific details like background score and music; a plot/story executed; tweaking some laws/norms of real world setting; so as to provide the users an engrossing experience. The difficulty level of few operations is reduced in the system such as auto correction and navigation while steering, sudden change of visual context so that the user makes the most of the interactive aspects of the game in the limited amount of time (5 minutes).

The focus of the virtual system is to provide an engaging and an entertaining system wherein user controls the actions and system controls the flow of actions. The development followed a rapid prototyping and iterative model wherein essential components such as motion and sound spatialization, were first developed. They were iterated with constant testing and evaluation while other details and effects were added during the entire process. The system is a success because it involves good user study and thus modeling the system to make a fun and interactive system wherein a lot of stuff happens in a small period of time. Users are provided with a wide range of visual effects and modes to interact with these effects.

Virtual Environmentsfor Treating the Fear of Heights

The paper reflects an exhaustive experimental research carried out to understand the background of Acrophobia (fear of heights) and a Virtual Reality system being developed and evaluated to ascertain its effectiveness in treating Acrophobia. Acrophobia is usually treated through System desensitization wherein subjects are asked to imagine the situation at heights; and Graded exposure or invivo treatment wherein they are gradually exposed to heights in real world and their responses are recorded.

The VR system was developed to provide the real world setting in which users could be treated.  In order to provide a real world presence, they tried using a detailed monoscopic image augmented with texture mapping on Head mounted displays. Three environments were developed for the experiment – Elevators, Balcony and bridges. Apart from visual effects of height, the setting was made to provide a true degree of immersion with platforms, guard rails for elevators and balcony. All environments had varying levels of height/difficulty which user could realize from the system.

The experiment was carried out in controlled setting and subject’s responses like anxiety, nausea, and weakness in knees were recorded. Congruent to real world treatment, subjects habituated to a specific height and faced increase anxiety with increase in height in the virtual system. Study also showed more positive results than the conventional method of Systematic desensitization, attributing to its success. However, there are few questions such as if the feeling of anxiety, nausea, nervousness could also be due to other factors such as discomfort with HMD, first time experience with HMD and virtual reality, probable visual impairment with the user etc. rather than the effectiveness of the system w.r.t details and virtual effects.

Merging Virtual Objects with the Real World: Seeing Ultrasound Imagery within the Patient

The paper mentions the background study, research carried out to develop a system which acquires and displays ultrasound echography data in real time. The approach was to retrieve real time 2D data and image slices through Ultrasound system and construct it in 3D space. The 3D visual from can be geometric (e.g polygons) or image based (e.g voxels). The 3D volume is to be incrementally updated with real time 2D ultrasound images.

The product architecture consisted of a HMD with Polhemus sensor, 2D ultrasound scanner and image generation graphics computer. The sensor used to track both the ultrasound transducer for 2D images and also the HMD movement. The ultrasound 2D pixels are rendered in a sphere display in 3D, appearing as sequence of splices. The left eye displayed the system generated 3D model mounted on the real world image while the right eye displayed the real world image.

The system had some limitations – low resolution of HMD images, system lag where in the 3D transformation of 2D ultrasound images was not able to keep up with the movement of HMD (requiring 3D sphere to be re-rendered). The 3D image appeared to be just pasted over the background. To fix this, the 3D image was displayed in a hollow synthetic hole to give an impression that it exists within the patient. However, this obscured the ultrasound transducer. This required retrieving the correct range of elements from HMD so that they real and synthetic images could be rendered based on their depth. This would make such systems usable in several medical and architectural domains.