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CPSC 533CStatic and Moving Patterns
Presented by Ken Deeter
Slides borrowed from Colin Ware’s PPT Slides
Gestalt Laws
• Gestalt = German for “Pattern”
• Laws of “pattern perception”– Proposed mechanisms were wrong– Rules themselves still have value
Proximity
• “Things that are close together are perceptually grouped together”
• Rule: Best way of emphasizing relationships between different data entities is to place them in proximity in a display.
Proximity example
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x
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Similarity
• Similar elements (shape, color) are grouped together.
• Combine with separable dimensions to assist with visual segmentation.
• Rule: Related visual elements should look similar
Similarity Example
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Continuity
• People are more likely to construct visual groupings out of elements that are smooth and continuous, rather than ones that contain abrupt changes in direction.
• Implies connectedness, which is stronger than proximity. (pg 207 fig 6.8)
• Rule: use connections to show relations
Continuity Example
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a b c
Connectedness Example
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c d
Symmetry
• Symmetrical elements emphasizes a relationship.
• Possible use: use symmetry in an interface to emphasize similarity (figure 6.11 pg 209)
• Rule: Use symmetry to relate visual elements.
Symmetry Example
Closure
• Humans tend to look for closed contours.• Closed contours segment visual space.
Organizing using these segmented regions is stronger than proximity.
• Common uses are Venn Diagrams or Application Windows
• Rule: Use closed regions to segment visual space, group smaller elements.
Closure Examples
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Relative Size
• Smaller components of a pattern tend to be perceived as objects.
• See Figure 6.15 pg 212
Figure and Ground
• What is foreground and what is background?
• Combination of other laws to segment image into fg/bg
Contours
• People see contours where they don’t really exist.
• Illusory contour (figure 6.18 pg 215)
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Transparency• Transparency is perceived only when good
continuity and color correspondence exists.
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Overlap
• Perception of overlapping textures depends on visual interference between two patterns
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c d
Perceptual Syntax
• Various types of illustrations already contain syntax that uses Gestalt principles to code information.– Node-link graphs (fig 6.29 pg 226)– Geographical Maps (fig 6.30 pg 228)– TreeMap (fig 6.31 pg 229)
Patterns in Motion
• Correspondence problem: for motion to work, humans need to perceive correspondence of visual elements between different frames.– Limit motion of elements
– Differentiate elements using shape/color/orientation
• Done incorrectly, results in “wagon wheel effect”
• Vary attributes to make correlation easier.
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Form and Contour in Motion
• Visual elements can be classified based on differences in movement, with comparable precision to static attributes.
Moving Frames
• Motion perception highly depend on context.
• Examples:– Synched moving dots (fig
6.34 pg 234)
– Dot in Moving frame: often perceived as dot moving instead of frame moving.
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Causality
• Perception of causality between two movements highly dependent on time between movements.– Some experimental results suggest 160ms as
maximum time for perceiving causality between two motions
• Can use specific motions to encode causal relationships in data.
Causality cont.
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100 200
50%
100%
Time (msec.)
Direct LaunchingDelayed launchingNo causality
Animate Motion
• Humans are very good at perceiving:– Biological motion– Expressiveness in motion
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