Nonphotorealistic Visualization of Multidimensional Datasets SIGGRAPH 2001 Christopher G. Healey Department of Computer Science, North Carolina State University [email protected]http://www.csc.ncsu.edu/faculty/healey Supported by NSF-IIS-9988507, NSF-ACI-0083421
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Nonphotorealistic Visualization of Multidimensional Datasets SIGGRAPH 2001 Christopher G. Healey Department of Computer Science, North Carolina State University.
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Nonphotorealistic Visualization
of Multidimensional DatasetsSIGGRAPH 2001
Christopher G. HealeyDepartment of Computer Science, North Carolina State
1 = dark blue bright pink2 = 0.25 1.153 = 0º 90º4 = 1x1 3x3
Cognitive Vision
• Psychological study of the human visual system
• Perceptual (preattentive) features used to perform simple tasks in < 200 milliseconds– features: hue, intensity, orientation, size, length, curvature,
closure, motion, depth of field, 3D cues– tasks: target detection, boundary detection, region
tracking, counting and estimation
• Perceptual (preattentive) tasks performed independent of display size
• Develop, extend, and apply results to visualization
Preattentive Processing Video
• How can we choose effectively multiple hues?
• Suppose: { A, B } Suppose: { A, B, C, D, E, F }
• Rapidly and accurately identifiable colors?
• Equally distinguishable colors?
• Maximum number of colors?
• Three selection criteria: color distance, linear separation, color category
Effective Hue Selection
A B A B C D E F
Colour Distance
A
B
C
CIE LUV isoluminant slice; AB = AC implies equal perceived colour difference
Linear Separation
Without linear separation (T in A & B, harder) vs. with linear separation (T in A & C, easier)
A
B
T
C
Colour Category
red
purpleblue
green
B
A
T
Between named categories (T & B, harder) vs. within named categories (T & A, easier)
Distance / Linear Separation
B
GY
Y
R
P
l
d
d
Constant linear separation l, constant distance d to two nearest neighbours
Example Experiment Displays
Target: red square; 3-colour, 17 element displays and 7-colour, 49 element displays
3 colours17 elements
7 colours49 elements
3-Color w/LUV, Separation
7-Color w/LUV, Separation
7-Color w/LUV, Separation, Category
CT Volume Visualization
Perceptual Texture Elements
• Design perceptual texture elements (pexels)
• Pexels support variation of perceptual texture dimensions height, density, regularity
• Attach a pexel to each data element
• Element attributes control pexel appearance
• Psychophysical experiments used to measure:– perceptual salience of each texture dimension– visual interference between texture dimensions
Pexel Examples
Regularity Density Height
Example “Taller” Display
Example “Regular” Display
Example “Regular” Display
Results
• Subject accuracy used to measure performance
• Taller pexels identified preattentively with no interference (93% accuracy)
• Irregular difficult to identify (76% accuracy); height, density interference
• Regular cannot be identified (50% accuracy)
Typhoon Visualization
n = 572,474m = 3
A1 = windspeed;A2 = pressure;A3 = precipitation
V1 = height;V2 = density;V3 = color
1 = short tall;2 = dense sparse;3 = blue purple
Typhoon Amber approaches Taiwan, August 28, 1997
Typhoon Visualization
n = 572,474m = 3
A1 = windspeed;A2 = pressure;A3 = precipitation
V1 = height;V2 = density;V3 = color
1 = short tall;2 = dense sparse;3 = blue purple
Typhoon Amber strikes Taiwan, August 29, 1997
Impressionism
• Underlying principles of impressionist art:– Object and environment interpenetrate– Colour acquires independence– Show a small section of nature– Minimize perspective– Solicit a viewer’s optics
• Hue, luminance, color explicitly studied and controlled
• Other stroke and style properties correspond closely to low-level visual features– path, length, energy, coarseness, weight
• Can we bind data attributes with stroke properties?
• Can we use perception to control painterly rendering?
Water Lilies (The Clouds)
1903; Oil on canvas, 74.6 x 105.3 cm (29 3/8 x 41 7/16 in); Private collection
Rock Arch West of Etretat (The Manneport)
1883; Oil on canvas, 65.4 x 81.3 cm (25 3/4 x 32 in); Metropolitan Museum of Art, New York
Wheat Field
1889; Oil on canvas, 73.5 x 92.5 cm (29 x 36 1/2 in); Narodni Galerie, Prague
Gray Weather, Grande Jatte
1888; Oil on canvas, 27 3/4 x 34 in; Philadelphia Museum of Art. Walter H. Annenberg Collection