Representing Flow Colin Ware UNH We can do

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Representing Flow Colin Ware UNH

Representing Flow Colin Ware UNH

We can do better than this

We can do better than this

2 D vector fields n Vector components n n Direction Magnitude Orientation Vector sign

2 D vector fields n Vector components n n Direction Magnitude Orientation Vector sign bit

2 D Flow visualization • A landmark study n. Orient n. Direction n. Magnitude

2 D Flow visualization • A landmark study n. Orient n. Direction n. Magnitude - Image courtesy of Dr. Laidlaw et al.

Perceptual issues n Luminance contrast for detail n n Red on green is hard

Perceptual issues n Luminance contrast for detail n n Red on green is hard to see (illustrate) Natural semantics for signalling “more” Longer n Wider n More dense n More contrasty n More vivid The background is critical n

Particle systems for flow vis. n n Particles are born (randomly in space) Have

Particle systems for flow vis. n n Particles are born (randomly in space) Have a behavior (moving with the flow) n n They leave a trail (a pathline) Color can change (with speed or age) Width can change (speed or age) Particles die

Theory of contour finding Contour finding mechanisms A single column in V 1 Field

Theory of contour finding Contour finding mechanisms A single column in V 1 Field Hayes Hess

The next stage – rapid propagation Prediction Weakest Contour Signal Strongest Contour Signal

The next stage – rapid propagation Prediction Weakest Contour Signal Strongest Contour Signal

2 D Flow visualization • A landmark study n. Orient n. Direction n. Magnitude

2 D Flow visualization • A landmark study n. Orient n. Direction n. Magnitude - Image courtesy of Dr. Laidlaw et al.

How to add VSB? Halle, 1868 Asymmetry along path Terminations Some neurons respond only

How to add VSB? Halle, 1868 Asymmetry along path Terminations Some neurons respond only with terminations in the receptive field. Halle’s “little stroaks” Fowler and Ware (1988)

Important factors n n Continuity tangential to flow sream Lightness contrast with background (clarity)

Important factors n n Continuity tangential to flow sream Lightness contrast with background (clarity) Show direction using asymmetry along path Use color width | length | contrast | density for speed, or a combination n n Add symbols if you like Trace forward and/or backward.

A real challenge

A real challenge

Many sliders

Many sliders