A Model of Spatial Directness in Interactive Visualization Stefan - - PowerPoint PPT Presentation

A Model of Spatial Directness in Interactive Visualization

Stefan Bruckner

Department of Informatics University of Bergen, Norway

Motivation (1)

• What is “directness” in the context of

interactive visualization?

– Is it a useful notion for better understanding the interplay between visualization and interaction? – What are the (sub-)dimensions of directness? – Can we measure it? Can we predict it?

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Motivation (2)

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Modeling Directness (1)

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Modeling Directness (2)

• Two dimensions of directness

– Visualization-interaction (vi) directness – Output-manipulation (om) directness

• Higher directness means that respective

mappings are “closer” to being their respective inverse

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Example: Point Picking in VolVis

• We encounter many values

along a viewing ray

• We can only display a single

color per pixel

• Higher vi-directness, if

compositing function can be inverted

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Types of Compositing (1)

intensity profile along a viewing ray

depth maximum intensity averaging accumulation first hit data value

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Types of Compositing (2)

intensity profile along a viewing ray

depth maximum intensity averaging accumulation first hit data value

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Types of Compositing (3)

intensity profile along a viewing ray

depth maximum intensity averaging accumulation first hit data value

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Types of Compositing (4)

intensity profile along a viewing ray

depth maximum intensity averaging accumulation first hit data value

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Types of Compositing (5)

intensity profile along a viewing ray

depth maximum intensity averaging accumulation first hit data value

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Scenarios (1)

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Scenarios (2)

• 2D visualization of 2D

data on a touchscreen (e.g., geographical maps)

• Highest visibility point

picking on a touchscreen in volume rendering

• Non-spatial interaction

(e.g., transfer function editing) on a touchscreen

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Scenarios (3)

• Surface-based

visualization in a monitor & mouse setup

• Direct volume rendering

in a monitor & mouse setup

• Proxy-based interaction

in a monitor and mouse setup

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Towards Measuring Directness

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importance/relevance

• f a data location x;

models user tasks

• Vis. Theory – Quo Vadis? (1)
• Theories can be

– Descriptive: describe/order/classify existing solutions, enabling a better understanding – Evaluative: enable the comparison between sets

• f alternatives

– Generative: enable the synthetization of new (improved) solutions

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• Vis. Theory – Quo Vadis? (2)
• Formulate objective measures that capture

relevant properties of visualization techniques in a computable form

• Associate these measures with task

performance, make testable predictions, and actually test them

• Perform in-silico “user studies” before

evaluating visualization techniques

• Synthesize new visualization methods

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