Summaries by gr8dhage
Virtual Environments for Treating the Fear of Heights
-Larry F. Hodges, Rob Kooper, Thomas C. Meyer, Barbara O. Rothbaum,Dan Opdyke, Johannes J. de Graaff, James S. Williford, MaxM,North
The paper describes a first of its kind study of using Virtual Reality techniques for the treatment of a phobia. This study in particular describes patients studying from acrophobia or a fear of heights and the virtual reality environment which was used as a desensitization treatment on them. The authors firstly created 3 scenarios in the virtual environment designed to induce symptoms of fear and anxiety in acrophobic people. The scenarios namely an open elevator, a series of balconies and a series of bridges at various heights were poorly constructed because of some of the processing limitations at the time this paper was published. The patients were immersed in this environment by using a head mounted display and placing them inside a specially constructed wooden platform with railings too heighten the sense of realism. Despite the poor quality of the graphics, the nature of virtual reality ensured that the users were completely immersed in the virtual environment. This is evident from the fact that they experienced sweating, nervousness, tension, physical discomfort and similar physical indications of acrophobia when undergoing the treatment. The results collected after about 7 weeks of treatment and compared with non-treated patients showed considerable improvement in the acrophobic patients with regards to tolerability of heights.
The authors describe their study as a “remarkable success” and I would have to agree with them on that account. One of the implications of this study, which I am very much fascinated by, is how immersion in virtual environments is not directly related to photorealistic graphics. It would have been difficult to calculate the level of immersion in normal studies but the physical symptoms shown by the acrophobic patients are clearly indicative of this fact. Indeed the authors’ work has proved to be one of the few practically useful applications of virtual reality and is still being widely used today. As the study is rather simple and self contained I don’t have any further questions for the authors.
Merging Virtual Objects with the Real World:Seeing Ultrasound Imagery within the Patient
-Michael Bajura, Henry Fuchs, and Ryutarou Ohbuchi
The paper describes two complementary techniques developed by Bajura and his colleagues to embed virtual imagery into the real world. The first sub-system can be used to generate 3D content models from a standard 2D ultrasound image acquisition system. The second sub-system uses a Head Mounted Display (HMD) to overlay the acquired 2D image slices on top of the real world at their appropriate 3D position. The particularly interesting and more robust part of their work is the 3D reconstruction of 2D image slices. The 2D image slices are acquired at a constant rate and a sensor (Polhemus) on the ultrasound transducer for tracking the movement and rotation of the transducer. Each of the 2D slices is placed and oriented in 3D based on the sensor data. Each pixel in the 2D image slice becomes a spherical voxel during the construction. If overlapping image slices are acquired the voxels are updated by using temporal reconstruction based on simple auto regressive moving average filtering. The second sub-sytem displays the data acquired in the previous step to the user. This is done via a HMD that contains head movement tracking sensors and a camera to obtain the user’s view. The user’s view is obtained and then the system computes the positions of the 2D slices from the user’s perspective. These slices then overlay the camera feed and the new generated image is displayed to the user (right eye only).
Personally, I really liked the system. Bajura and co have evidently put considerable efforts to get this system working. However, the second part of the paper about displaying the ultrasound slices from a user’s perspective definitely has some room for improvement. The authors have already addressed some of these issues in section 6.1. Particularly, I did not find the augmented image, shown in Figure 6, useful as the obscured 2D slices don’t seem to provide any extraneous information. However, doctors should be the rightful judge of that. The technologies at that time had a lot of restrictions and overheads. So the only question I would like to ask the authors is given more advanced sensors available today and more processing power at their disposal what are some of the interesting things they could have worked on.
Designing Interactive Theme Park Rides
-Jesse Schell and Joe Shochet
This paper describes a novel virtual reality experience as an interactive theme park ride at Disneyland. The ride is aimed to be a fun social experience and hence the main focus is to give the users value for their money. A physical helm and cannons in the real world are used by the players to attack and plunder other pirate ships rendered virtually. Large screens surround the players to create more immersion. 3D surround sound and physical shaking of the boat with the waves or on hit by a cannon ball reinforces the players that they are pirates on a mission.
I find this to be a really awesome way to use virtual reality systems. Indeed a good mix of real and virtual worlds can provide unparalleled experiences to the audience. I think the creators of the ride had the same goal and achieved it to a good degree. What I would like to see is having screens on all sides along with the roof and floor. I feel that could potentially be more believable. Also upgrading the system to use modern hardware as I find the graphics neither realistic nor cartoonish enough to get the kind of feel theme rides intend to deliver. I would also like to delve into some more details about the rapid prototyping system that these guys used to build this system on a short timeline.
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