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 a surface

- 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)

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

Database

Acquisition (scanners, sensors, …)

Raw Data Filtered

Data Mapping Visualize

Filtering Rendering

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

Image credits: Jeff Heer, prefuse

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.

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

Image credits: van Wijk, Value of Visualization

D – Data V – Visualization S - Specification

P – Perception/Cognition of the user (mental model) K – Knowledge E – Exploration through interaction

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”