Week 12 Summaries
A Survey of Design Issues in Spatial Input
The paper addresses the issues designers should consider and lists a set of design principles for designing interfaces for virtual environments. 3D interaction space is very different to the 2D space we use in everyday computing. The authors combine the information from their experiences and tests with the previous work in the field. They divided the entire set of issues into 2 parts – Human Perception and Ergonomic concerns.
Understanding and experiencing 3D space are very different aspects. The authors list a bunch of issues which facilitate 3D space perception like spatial references, various gesture techniques and two-handed interactions etc. Then he goes on to discuss user perception in multi-dimensional tasks and compares it with independent input dimensions. They felt it was better to reduce the number of dimensions. Then they talked about Control Metaphors. They talked about ray-casting along with the previous metaphors. Dynamic Target Acquisition has been an issue with interaction between the user and virtual objects. Here they talked about ray-casting along with direct positioning and cone-casting. Recalibration is necessary to map absolute position to the logical position. The authors talked about Command-based, Ratcheting and Continuous techniques for it.
Then they go on to discuss the ergonomic issues. The first big problem comes with handling precise control with respect to position and orientation. When it comes to spatial volume, users of a spatial interface which require movements relative to a fixed frame-of-reference in their environment may experience reduced task performance due to cognitive load, fatigue, or both. Using mouse and keyboard is not a good idea. Touch-screens probably are a better alternative. Clutching is one of the hardest problems to solve. Snapshot might be a good solution to that. In the last point, they discuss about human aspects such as fatigue and uncomfortable or comfortable postures or movements.
All in all it seems like there are some good answers and questions along with some open-ended discussions. There is still a lot of scope for research and work with changing and newer more comfortable technologies. With the size of peripherals changing and even in some cases modes of interaction completely changing.
Exploring 3D Navigation: Combining Speed-coupled Flying with Orbiting
The paper talks about navigating 3D space in virtual environments, categorizes existing techniques and introduces some new ones. They talk about the various techniques for 3D navigation and orienting the user in the 3D world. The first technique talks about inspection like point of interest and mainly deals with object manipulation. They also talked about Ghost Copy technique. Searching technique on the other hand deals with finding something in a complex world because of occlusion. Inverse fog (making things transparent), scaling and ephemeral world compression help deal with this. Ruberneck Navigation helps in positioning (spatial position and orientation) and the author uses this along with metaphor of possessing. When the user wants to access something, he is teleported to that position. He can drag and object and is positioned right there. The third technique talks about coupling speed with the height. The faster the user goes, the higher he goes and vice versa. And they combined this with orbiting. The tested this extensively.
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