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Explore the concept of affordances in navigation, from physical to cognitive affordances, evaluating tools like World-in-hand, Path drawing, and Flying Vehicle Control. Understand the importance of focus and context, spatial knowledge encoding, and landmark placement for effective navigation interfaces. Discover methods such as Point of Interest Navigation and Center of Workspace Navigation for improved interaction. Delve into the cost of knowledge in information retrieval through various navigation techniques like Flying and Zooming, as studied by George Furnas.
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Navigation • Moving the viewpoint as a cost of knowledge
Navigation • Metaphors and methods • Affordances • Ultimately about getting information • Geographic Space • Non-metaphoric navigation
The affordance concept • Term coined by JJ Gibson (direct realist) • Properties of the world perceived in terms of potential for action (physical model, direct perception) • Physical affordances • Cognitive affordances
Walking-on-the-spot interface • Use in virtual reality system • Actually a head bobbing interface. • Real-walking both more natural and better presence than either flying or walking on the spot.
Evaluation (Ware and Osborne 1990) • Exploration and Explanation • Cognitive and Physical Affordance • Task 1: Find areas of detail in the scene • Task 2: Make the best movie For examples see classic 3D user interaction techniques for immersive virtual reality revisited
World-in-hand Good for discrete objects Poor affordances for looking scale changes – detail Problem with center of rotation when extended scenes
Flying Vehicle Control Hardest to learn but most flexible Non-linear velocity control Spontaneous switch in mental model The predictor as solution
Eyeball in hand Easiest under some circumstances Poor physical affordances for many views Subjects sometimes acted as if model were actually present
Map:ahead-upversustrack-up North-up for shared environment Ahead-up for novices View marker gives best of both
Mental maps • How do we encode space?
Seigel and White • Three kinds of spatial knowledge • Categorical (declarative) knowledge of landmarks. • Topological (procedural) knowledge of links between landmarks • Spatial (a cognitive spatial map). • Acquired in the above order
Colle and Reid’s study • Environment with rooms and objects • Test on relative locations of objects • Results show that relative direction was encoded for objects seen simultaneously but not for objects in different rooms • Implications: can generate maps quickly: should provide overviews. (ZUIs are a good idea)
Vinson’s design guidelines • There should be enough landmarks so that a small number are visible. • Each Landmark should be visually distinct from others • Landmarks should be visible at all navigable scales • Landmarks should be placed on major paths and intersections of paths
Non-metaphoric Focus+Context • Problem, how not to get lost: • Keep focus while remaining aware of the context. • Classic paper: Furnas, G. W., Generalized fisheye views. Human Factors in Computing Systems CHI '86 Conference Proceedings, Boston, April 13-17, 1986, 16-23.
Non metaphoric Interfaces • ZUIs Bederson-Zooming • Focus in context
Using 3D to give 2D context Perspective wall www.thebrain.com Dill, Bartram, Intelligent zoom
http://www.nass.usda.gov/research/Crop_acre97.html Table Lens
POI Navigation MacKinlay start • Point of interest. • Select a point of interest • Move the viewpoint to that point. Dist = t C VP + View direction reorientation.
Center of Workspace Navigation • COW navigation • Move objects to the center of the workspace. Zoom about the center. • Initially object-based became surface-based • exponential scale changes d = kt • : a factor of 4 per second (10 sec ~ scale by a million) • Better for rotations (people like to rotate around points of interest)
COW Navigation in Graph Visualizer 3D COW Viewpoint The Concept: Translate to center of workspace then scale
GeoZui3DZooming + 2 dof rotations Translate point on surface to center Then scale. Or translate and scale. (8 x per second)
Navigation as a Cost of Knowledge. How much information can we gain per unit time • Intra-saccade (0.04 sec) (Query execution) • An eye movement (0.5 sec) < 10 deg : 1 sec> 20 deg. • A hypertext click (1.5 sec but loss of context) • A pan or scroll (3 sec but we don’t get far) • Walking (30 sec. we don’t get far) • Flying (faster , but can be tuned) • Zooming, t = log (scale change) • Fisheye (max 5x). DragMag (max 30x)
Generalized fisheye viewsGeorge Furnas A distance function. (based on relevance) • Given a target item (focus) • Less relevant other items are dropped from the display.