Week 12 Summaries
Exploring 3D Navigation: Combining Speed-coupled Flying with Orbiting
This paper first presents a task-based taxonomy of navigation techniques for 3D virtual environment which categorized existing techniques. Inspired by this taxonomy, the authors propose several new techniques.
The authors try to use taxonomy to give a more disciplined exploration of the design space of navigation in 3D virtual environment. The taxonomy uses a task-based model. The designers firstly ask why use is trying to navigate. Then according to user’s goal they define the solution in terms of travel control and consider the user interface and navigation metaphor.
After the taxonomy, the authors first briefly introduce several new techniques: Object Manipulation, Ghost Copy, Inverse Fog/Scaling, Ephemeral World Compression, Possession and Rubberneck Navigation. Then they present a technique called Speed-coupled Flying with Orbit in details. This new technique enable user to easily and intuitively alternate between walking around an environment, getting an overview and examining objects. The Speed-coupled Flying technique couple speed control to height and tilt control by using a standard egocentric driving controls. Though dragging mouse in different direction, the user can transition seamlessly between and navigate within local and global views. An orbiting technique is also developed, which allows the user to easily get desired viewpoints of particular target objects, and combined with the speed-coupled flying technique.
To evaluate this new technique, two experiments were conducted. The first experiment compared the speed-coupled flying with orbit with other four navigation techniques. The average trial time as well as user satisfaction are used to evaluate these navigation techniques. The second experiment was to evaluate the ‘gliding’ behavior which is added to flaying with orbit to solve a problem observed in experiment 1. Both these two experiment shows that speed-couple flying with orbiting allows users navigate more efficiently in certain virtual environments.
A Survey of Design Issues in Spatial Input
In this paper, the authors present a survey of several design issues for developing effective free-space 3D user interface. These issues are grouped into two major categories, Human Perception and Ergonomics concerns.
For the human perception, the first issues is designer should consider is that user do not innately understand 3D reality but experience it. A number of issues may facilitate 3D space perception, including spatial references, relative gesture vs. absolute gesture, two-handed interaction, multisensory feedback, physical constraints and head tracking techniques. The second issue indicates controlling the DOF exposed to users. The needs or dimensionality should be task-specific. The third issue is the control metaphor including eyeball-in-hand metaphor, scene-in-hand metaphor, flying vehicle control and ray casting metaphor. For the task of dynamic target acquisition, several issues including use of transparency, ray casting vs. direct positioning and cone casting vs. ray casting should be considered. Recalibration mechanisms give three basic recalibration strategies: command-based, ratcheting and continuous issues.
For the Ergonomics concerns part, there are also several issues the designer should consider. Users may have difficulty controlling an interface that requires simultaneous, precise control of an object’s position and orientation. Dynamics and size of the working volume of the user’s hand should also be considered. The authors also point that it can be awkward and fatiguing to repeatedly switch between spatial input devices and traditional input devices. Designer could consider using voice input and touchscreen. Furthermore the clutching design is also important as well as the ergonomic details in spatial interfaces.
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