Pad++
A Zooming Graphical Sketchpad
for Exploring Alternative
Interface Physics
Benjamin B. Bederson, James D. Hollan,
Ken Perlin, Jonathan Meyer, David
Bacon, George Furnas
Presented by Evren Sirin
Overview
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Motivation
Description of Pad++
Visualization Examples with Pad++
Space-Scale Diagrams
Procedural Animation
Implementation
Critique
Motivation
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Massive amount of information
Current metaphor-based approach is limited
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When designing with metaphors you are limited to
those that exist
Metaphors don’t scale easily to larger amounts of
data
Metaphors only bridge concepts temporarily
Metaphors may be misleading
The alternative is to design using interface
physics
Informational Physics Strategy
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View information at multiple scales
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Elastic stretchable infinite sheet
Semantic zooming
Make it more intuitive and easier to find
specific information in large data spaces
 Filter or recommend a subset of the data
 Provide a useful substrate to structure
information
What is Pad++
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A general-purpose substrate creating
and interacting with structured
information based on a zoomable
interface
PadDraw: Real application based on
Pad++
Description
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Intuitive navigation
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Portals
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Provide views onto other areas (+filtering)
Index: sticky portal
Lenses
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Animated panning & zooming
Visual searching + Content-based search
Portals that change the way objects presented
Semantic zooming
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Change the way things look depending on their size
Visualization Examples
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Variable resolution for representation &
interaction
There is always more room to put
information “between the cracks”
Suitable for visualizing hierarchical data
HTML Browser
Directory Browser
TimeLine
Oval Document Layout
Space-Scale Diagrams
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Analytical tool for describing
multiscale spaces
Static representation of
multiscale movements
Used to solve two basic problem
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Joint pan & zoom
Shortest paths between two points
Simple space-scale diagram
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A one dimensional space-scale diagram of six points as the view zooms in from (a)
to (b) to (c) around the point q
Pan-zoom trajectories
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Basic pan-zoom trajectories are shown in the heavy dashed lines. (a) is a pure pan,
(b) is a pure zoom (out), and (c) is a zoom around the point q
Solving joint pan-zoom problem
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Solution to the simple joint pan-zoom problem. The trajectory s monotonically
approaches point (x2, z2) in both pan and zoom
Shortest path between two points
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Each arrow represents one unit of cast. Because zoom is logarithmic, it is often "shorter" to zoom
out (a), make a small pan (b), and zoom back in (c), than to make a large pan directly (d)
Procedural Animation
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User-definable animated objects
To support an informational physics in
which objects animate naturally
Clearly structured animated narrative vs.
assortment of disjoint temporal events
Simple widgets defined at a behavioral level
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Zoomable Choice Widget
Implementation
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Substrate implemented in C++
Scripting language interface
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Easily extensible (no need for C++ code)
Implemented as a widget in Tcl/Tk
Efficient byte-compiled language: KPL
Efficiency results
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600,000 Objects & 10 frames/sec
Rendering times  # of visible objects
Efficiency methods
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Spatial Indexing
Clustering
Refinement
Level-Of-Detail
Region Management
Clipping
Adjustable Frame Rate
Interruption
Ephemeral Objects
Optimized Image Rendering
My favorite sentence
If interface designers are to move
beyond window, icons, menus, and
pointers to explore a larger space of
interface possibility, additional ways of
thinking about interface that go beyond
the desktop metaphor are required.
Contributions
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Alternative to WIMP
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Informational physics strategy for interface
design
Exploring potentially more effective
computer-based mechanisms
Space-Scale Diagram
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Analytical tool for multiscale spaces
Notes on the references
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Sketchpad, Sutherland
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Pad, Perlin & Fox
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Semantic Zooming, Portals
Constraint-Based Drawing, Borning
Generalized Fisheye Views, Furnas
Perspective wall, Card, Robertson & Mackinlay
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The first interactive computer graphics
visualizing linear information by smoothly integrating detailed
and contextual views.
Information Visualizer, Card
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Information workspace, Cone-trees
Critique
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Strengths
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Effective complement to traditional metaphorbased approaches
Space-Scale Diagram
Weaknesses
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No experiment on HCI metrics
Orientation problems: Zooming loses overview
Jump back & forth between topics
What has happened to this topic?
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Pad++: version 0.9 available in UCSD
Jazz: in UMD
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General-purpose 2D graphics toolkit for creating ZUI
CounterPoint: Zoomable presentation tool
KidPad: a collaborative story authoring tool for children
PhotoMesa: Zoomable image browser
Zomit: generic package for developing ZUI
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Visualize biological data and to navigate in a large
space of biological information
Outline view
Zoom into files
Read contents
Zoom out & pan
Create a portal
Move away the copy
Portal is NOT a copy
Pan & zoom in a portal