GestaltLaws’of’Perceptual’ Organiza6on’web.engr.oregonstate.edu/.../lectures/Gestalt.pdf ·...
Transcript of GestaltLaws’of’Perceptual’ Organiza6on’web.engr.oregonstate.edu/.../lectures/Gestalt.pdf ·...
Gestalt Laws of Perceptual Organiza6on
CS 559 – March 30th Nadia Payet
How do we perceive objects?
Gestalt Psychology
• The Gestalt laws prescribe for us what we are to recognize ‘as one thing’ (Köhler, 1920) – Gestalt means “shape” or “form” in German.
• How smaller objects are grouped to form larger ones
• Rules of the organiza6on of perceptual scenes Heuris6cs
Problem statement
• Given a set of disconnected edges – Find a subset of these edges that form perceptually salient groups
– Use Gestalt principles to iden6fy these groups
• Reconnect objects that appear disconnected in the image (occlusion, illumina6on, …)
Gestalt Laws
• Proximity • Collinearity • Co-‐circularity • Con6nuity • Parallelism • Symmetry • Closure • Convexity • …
Perceptual Organiza6on
Perceptual Organiza6on
Symmetry
Perceptual Organiza6on
Symmetry
Similarity
Perceptual Organiza6on
Symmetry
Similarity
Proximity
Perceptual Organiza6on
Symmetry
Similarity
Proximity
Closure
Proximity
Lowe, AIJ 1987
Collinearity
Lowe, AIJ 1987
Collinearity
Zhu, PAMI 1999
Co-‐circularity
Zhu, PAMI 1999
Con6nuity
• Curvilinear con6nuity is measured by angle θ.
Parallelism
Lowe, AIJ 1987
Parallelism
Zhu, PAMI 1999
Symmetry
Zhu, PAMI 1999
Symmetry
• αi is the angle between line (p1,p2) and normal vectors at pi
• p1 and p2 are symmetric if α1 = α2 = α
Stark, ICCV 2009
Symmetry
• Represent axis of symmetry with a B-‐spline – Parameters form a descriptor vector
• Record length profile of the symmetry lines – PCA reduc6on to obtain a compact descriptor
Stark, ICCV 2009
Closure L2 measure of gaps is shown to be most consistent with human percep6on
Elder and Zucker, A Measure of Closure, 1994