IAT 355 Visual Analytics Space: View Transformations Lyn Bartram So much data, so little space: 1 • Rich data (many dimensions) • Huge amounts of data • Overplotting [Few] • patterns and relations across sets • Visual fragmentation • Decoding too many different visual forms IAT 355 | View transformations 2 Recall: Dimensional division • “splitting” dimensions across multiple linked views • Small multiples • Trellis displays • Scatterplot matrices IAT 355 | View transformations 3 Small multiples • use the same basic graphic or chart to display difference slices of a data set • rich, multi-dimensional data without trying to cram all that information into a single, overly-complex chart. • Singular design reduces decoding effort. • E. Tufte “The Visual Display of Quantitative Information,” p. 42 and “Envisioning Information,” p. 29 IAT 355 | View transformations 4 Small multiples IAT 355 | View transformations 5 Small multiples • Small multiples to convey n-dims. IAT 355 | View transformations 6 Horizon graphs IAT 355 | View transformations 7 Trellis plots IAT 355 | View transformations 8 Scatter plot matrices IAT 355 | View transformations 9 Multiple Views • “Guidelines for Using Multiple Views in Information Visualization” • Baldonado, Woodruff and Kichinsky AVI 00 IAT 355 | View transformations 10 Multiple Views: 8 Guidelines • Rule of Diversity: • Use multiple views when there is a diversity of attributes • Rule of Complementarity: • Multiple views should bring out correlations and/or disparities • Rule of Decomposition: “Divide and conquer”. • Help users visualize relevant chunks of complex data • Rule of Parsimony: • Use multiple views minimally IAT 355 | View transformations 11 8 Guidelines Cont’d • Rule of Space/Time Resource • Optimization: Balance spatial and temporal benefits of presenting and using the views • Rule of Self Evidence: • Use cues to make relationships apparent. • Rule of Consistency: • Keep views and state of multiple views consistent • Rule of attention management: • Use perceptual techniques to focus user attention IAT 355 | View transformations 12 View transformations • Location probes • Details on demand • Brushing • Magic lenses • Viewpoint controls • Zoom, pan, clip • Overview+detail • Distortions (Focus+Context) • Bifocal : Perspective Wall, Document Lens • Polyfocal : Table Lens • Based on levels of interest: Fish Eye Lens IAT 355 | View transformations 13 So much data, so little space: 2 Location probes • Details on demand • Brushing • Magic lenses IAT 355 | View transformations 14 Details on Demand Popup windows Adjacent frames So much data, so little space: 2 Location probes • Details on demand • Brushing • Magic lenses IAT 355 | View transformations 16 So much data, so little space: 2 Location probes • Details on demand • Brushing • Magic lenses IAT 355 | View transformations 17 Magic lenses Magic lenses are probes that give an alternate view of a region in the Visual Structure in which the objects reveal additional properties IAT 355 | View transformations 18 Magic lens / tool glass Figure 4.29 Illustrating the concept of a magic lens. (a) shows a conventional map of an area, (b) shows the location of services (gas, water and electricity pipes) in the same area, and (c) a (movable) magic lens shows services in an area of interest, in context Figure 4.30 A molecular surface of the protein transferase coloured by electrostatic potential bound to DNA shown as a schematic. (ID = 10mh). The magic lens window allows a view of the atomic structure bonding to be shown, with the bound ligand structure highlighted as cylinders, thereby providing a view inside the protein Source: By kind permission of Tom Oldfield and Michael Hartshorn So much data, so little space: 3 • Scale - Many data sets are too large to visualize on one screen • May simply be too many cases • May be too many variables • May only be able to highlight particular cases or particular variables, but viewer’s focus may change from time to time IAT 355 | View transformations 21 Important Concepts • Portals • Lenses • Sticky objects • Semantic zooming IAT 355 | View transformations 22 Portals • Views onto another place in the world • Implemented typically as separate rectangular region • Zooming, panning, I/O all work independently in there • Can be used to create overviews or focus regions IAT 355 | View transformations 23 Lenses • Rectangular regions/objects that can be moved around on display • Objects that alter the appearance and behavior of objects seen through them IAT 355 | View transformations 24 Sticky Objects • Objects in the world that do not respond to the basic zoom/pan interface physics • Objects are “stuck” to the display • They never change position • They never change size IAT 355 | View transformations 25 Common Solution- Scroll/Pan • Provide a larger, virtual screen by allowing user to move to different areas • Requires one or more of • Dedicated mouse button/wheel • Peripheral scroll bars – Takes screen space – Requires mouse move • Only get to see one piece IAT 355 | View transformations 26 Panning and Zooming • Panning • Smooth movement of camera across scene (or scene moves and camera stays still) • Zooming • Increasing or decreasing the magnification of the objects in a scene • Useful for changing focal point IAT 355 | View transformations 27 Pan and Zoom How to show a lot of information in a small space? • Multiple Levels of Resolution • The view changes depending on the “distance” from the viewer to the objects • Distortion-based techniques • Keep a steady overview, make some objects larger while simultaneously shrinking others IAT 355 | View transformations 28 Zooming • Standard Zooming • Get close in to see information in more detail • Example: Google earth zooming in • Intelligent Zooming • Show semantically relevant information out of proportion • Smart speed up and slow down • Example: speed-dependent zooming, Igarishi & Hinkley • Semantic Zooming • Zooming can be conceptual as opposed to simply reducing pixels • Example tool: Pad++ and Piccolo projects • http://hcil.cs.umd.edu/video/1998/1998_pad.mpg IAT 355 | View transformations 29 Speed-dependent Zooming by Igarashi & Hinkley 2000 http://www-ui.is.s.u-tokyo.ac.jp/~takeo/video/autozoom.mov http://www-ui.is.s.u-tokyo.ac.jp/~takeo/java/autozoom/ autozoom.htm IAT 355 | View transformations 30 Pad++ • An infinite 2D plane • Can get infinitely close to the surface too • Navigate by panning and zooming • Pan: • move around on the plane • Zoom: • move closer to and farther from the plane • http://hcil.cs.umd.edu/video/1998/1998_pad.mpg IAT 355 | View transformations 31 The Role of Portals • All this panning and zooming can get confusing (maybe even dizzying) • Portals allow for zooming a small piece of the dataset while keeping everything else in the same position • Pad++ is one big stretchy sheet • A portal is more like a special window into a piece of the sheet • That window behaves independently of the rest IAT 355 | View transformations 32 Space-Scale Diagrams (Furnas & Bederson 95) • Original figure, shown at various scales • Horizontal axis is standard, vertical is scale IAT 355 | View transformations 33 Space-Scale Diagrams (Furnas & Bederson 95) • User has a fixed-sized viewing window • Moving it through 3D space yields all possible sequences of pan & zoom IAT 355 | View transformations 34 Space-Scale Diagrams (Furnas & Bederson 95) • If you move the origin of the 2D plane, the properties of the original 2D picture do not change • Therefore, the absolute angles between the rays should not be assigned any meaning IAT 355 | View transformations 35 Space-Scale Diagrams (Furnas & Bederson 95) • We can think of this in terms of 1D • When zoomed out, you can see wider set of points IAT 355 | View transformations 36 Space-Scale Diagrams (Furnas & Bederson 95) What about panning and zooming at the same time? • Panning is linear • Zooming is logarithmic • The two effects interact • If you compute the two separately and run them in parallel you get problems • When zooming in, things go exponentially fast • Panning can’t keep up – The target “runs away” out of view IAT 355 | View transformations 37 How to Pan While Zooming? IAT 355 | View transformations 38 How to Pan While Zooming? IAT 355 | View transformations 39 Navigation in Pad++ • How to keep from getting lost? • Animate the traversal from one object to another using “hyperlinks” • If the target is more than one screen away, zoom out, pan over, and zoom back in • Goal: help viewer maintain context IAT 355 | View transformations 40 Semantic Zooming • Zooming that is not simply a change in size or scale like simple magnification • Objects change fundamental appearance/presence at different zoom levels • Zooming is like step function with boundaries where a semantic transition takes place IAT 355 | View transformations 41 Standard vs. Semantic Zooming • Geometric (standard) zooming: • The view depends on the physical properties of what is being viewed • Semantic Zooming: • When zooming away, instead of seeing a scaled-down version of an object, see a different representation • The representation shown depends on the meaning to be imparted. IAT 355 | View transformations 42 Concept of Semantic Zoom • Infinitely scalable painting program • close in, see flecks of paint • farther away, see paint strokes • farther still, see the holistic impression of the painting • farther still, see the artist sitting at the easel IAT 355 | View transformations 43 Examples of Semantic Zoom • Information Maps • zoom into