Visualization Process

Alark Joshi Task-specific Visualization Design

• LA Treinish, Task-specific visualization design, IEEE Computer Graphics and Applications, 1999

• Generalized visualization systems are less suitable for environments with specific tasks and user needs • Prototypes help with defining/refining user needs • Iterative process of developing novel techniques to converge on meeting user needs Class I – 2D visualization

• Provide colormapped or contoured 2D scalar fields • Minimal interaction at a specific layer • Can only show a few parameters simultaneously Class II - 2D and 2.5D analysis

- Precipitable water as the height - Pseudo-colored by temperature - Arrows indicate wind direction and speed is encoded in terms of color - Local coastline (black) - State boundaries (white) - River map (blue)

Precipitable water as a surface Class III – 3D browsing

- Cartographically projected true height of the terrain - Coastline (black) - State boundaries (white) - Blue puddles show regions of heavy rainfall - Vector arrows show surface wind velocity color-coded with speed

- Visualization used to predict rainfall for the closing ceremony of the Atlanta Olympics in 1996 Class III – 3D browsing

- Cartographically projected true height of the terrain - Coastline (black) - State boundaries (white) - Blue puddles show regions of heavy rainfall - Vector arrows show surface wind velocity color-coded with speed

- Visualization used to predict rainfall for the closing ceremony of the Atlanta Olympics in 1996 Class IV – 3D analysis

- Pseudo-colored Precipitation (Surface variable) - Relative humidity (Upper air variable) shown as a translucent white surface - Temperature shown as a vertical slice - Coastline (black) - State boundaries (white) - Vector arrows encode speed and direction of wind velocity Sequence illustrating typical use Blog comments

• Eddie – “The application of design principles based on user needs to visualization certainly stands to reason… provides a concrete example” • Danny – “ This paper argues that one size of software does not fit all.” • Tim – “proposed design process can and should be applied to the development of all visualization tools, whether the user audience is very large or very small.”

Overview of the Process Demo

• Voreen • Colorbrewer • Map of the Market Visualization Pipeline

Simulation

Filtered Database Raw Data Mapping Visualize Data

Acquisition (scanners, Filtering Rendering sensors, …) Filtering

• Data input -> Data output • Data format conversion • Clipping/cropping/denoising • Slicing • Resampling • Interpolation/approximation • Classification/segmentation Mapping

• Data input -> Graphical Primitives • Scalar field -> Surface, Lines • Vector field -> Vectors/Arrows/Streamlines • Tensor field -> Tensor glyphs/Ellipsoids • 3D Field -> volume visualization • High dimensional data -> Map to 2D/3D

Image credits: SCI Utah, Daniel Weiskopf Rendering

• Render graphics primitives such as – Points – Lines – Surfaces – Volumes • With attributes such as – Color – Texture – Transparency Visualization Pipeline

Image credits: Voreen Visualization Pipeline

• Example: simulation of flow within a fluid around a wing Cyclical Model

Image credits: van Wijk, Value of Visualization Cyclical Model

prefuse.org - set of software tools for creating rich interactive data visualizations. - original prefuse toolkit provides a visualization framework for Java - prefuse flare toolkit provides visualization and animation tools for ActionScript and the Adobe Flash Player.

Image credits: Jeff Heer, prefuse Cyclical Model Scenarios

• Video/Movie mode Scenarios

• Feature Tracking Scenarios

• Interactive post processing/visualization Scenarios

• Interactive computational steering Value of Visualization

• Jarke J. van Wijk, "The Value of Visualization," IEEE Visualization, 2005. • How to assess the value of visualization?

• We all agree that a visualization should be “effective” and “efficient” • Van Wijk provides an economic model of visualization where he discusses the value in terms of associated costs and gains Economic Model of Visualization

D – Data P – Perception/Cognition of the user (mental model) V – Visualization K – Knowledge S - Specification E – Exploration through interaction

Image credits: van Wijk, Value of Visualization Discussion

• Technology – Innovation • Art – Does it merely serve as art? Should we be learning from the field of art? • Science – Is there a Science of Visualization?

Blog comments

• Josh – “Negative Knowledge … occurs when a visualization misleads a user to gaining false or "negative" knowledge” • Bill – “If Visualization is considered Tech should the bulk of the funding be going to applications that have the promise of becoming mainstream technology? Shouldn’t we be starting more companies?” Blog comments

• Peter – “… does not present a consistent set of ideas that lead to a conclusion or conclusions. … raises many interesting questions regarding the value of visualization. … personally have a hard time believing that it can be effectively assessed.” • Archana – “Too much interaction will make the visualization more subjective and customization can be misleading.” • Danny liked the comment in the paper – “the purpose of vis is funding, not insight”