Title: Local shape of pictorial relief
Authors: Koenderink, Jan ×
van Doorn, Andrea
Wagemans, Johan #
Issue Date: 2014
Publisher: Pion Ltd.
Series Title: i-Perception vol:5 pages:188-204
Abstract: How is pictorial relief represented in visual awareness? Certainly not as a “depth map,” but
perhaps as a map of local surface attitudes (Koenderink & van Doorn, 1995). Here we consider the
possibility that observers might instead, or concurrently, represent local surface shape, a geometrical
invariant with respect to motions. Observers judge local surface shape, in a picture of a piece of
sculpture, on a five-point categorical scale. Categories are cap–ridge–saddle–rut–cup–flat, where
“flat” denotes the absence of shape. We find that observers readily perform such a task, with full
resolution of a shape index scale (cap–ridge–saddle–rut–cup), and with excellent self-consistency
over days. There exist remarkable inter-observer differences. Over a group of 10 naive observers we
find that the dispersion of judgments peaks at the saddle category. There may be a relation of this
finding to the history of the topic—Alberti’s (1827) omission of the saddle category in his purportedly
exhaustive catalog of local surface shapes.
ISSN: 2041-6695
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory for Experimental Psychology
× corresponding author
# (joint) last author

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