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标题: Slices: A Shape-proxy Based on Planar Sections [打印本页]

作者: 晃晃 时间: 2011-12-28 11:37
标题: Slices: A Shape-proxy Based on Planar Sections
Slices: A Shape-proxy Based on Planar Sections

James McCrae Karan Singh Niloy J. Mitra

University of Toronto KAUST/UCL

Abstract

Minimalist object representations or shape-proxies that spark and

inspire human perception of shape remain an incompletely under-

stood, yet powerful aspect of visual communication. We explore

the use of planar sections, i.e., the contours of intersection of planes

with a 3D object, for creating shape abstractions, motivated by their

popularity in art and engineering. We ﬁrst perform a user study

to show that humans do deﬁne consistent and similar planar sec-

tion proxies for common objects. Interestingly, we observe a strong

correlation between user-deﬁned planes and geometric features of

objects. Further we show that the problem of ﬁnding the minimum

set of planes that capture a set of 3D geometric shape features is

both NP-hard and not always the proxy a user would pick. Guided

by the principles inferred from our user study, we present an algo-

rithm that progressively selects planes to maximize feature cover-

age, which in turn inﬂuence the selection of subsequent planes. The

algorithmic framework easily incorporates various shape features,

while their relative importance values are computed and validated

from the user study data. We use our algorithm to compute pla-

nar slices for various objects, validate their utility towards object

abstraction using a second user study, and conclude showing the

potential applications of the extracted planar slice shape proxies.

Keywords: abstraction, shape proxy, shape perception

1 Introduction

Over the last few decades, great strides have been made in the area

of acquisition and modeling of 3D geometry. The underlying shape

representation is typically a collection of polygons, popular for their

generality, rendering efﬁciency, and amenability to geometry pro-

cessing algorithms. Unfortunately, such a representation can be ex-

pensive and, in itself, neither conveys the essence of the depicted

object nor aids in our understanding of the represented shape.

Artists and sculptors have long explored minimalist shape proxies

to highlight deﬁning aspects of familiar objects (see Figure 2). As

humans, we effortlessly perceive the underlying shapes even from

such sectional representations, which greatly differ from their sur-

face representations. In fact, the sparse nature of these representa-

tions allows us to see otherwise occluded details and the absence of

unnecessary detail makes such artforms attractive, fascinating, and

sometimes mysterious. Evidence suggests that symbolic abstrac-

tions [Edwards 2002] dominate our mental model of objects. Thus

across cultures, we both recognize shape proxies quickly and tend

to communicate objects by drawing them as symbolic abstractions.

Planar section proxies are also motivated by medical and engineer-

ing visualization where section planes are used to illustrate the

interior details of complex shapes (see Figure 2). These planar-

sections often pass through anatomic landmarks or engineering fea-

tures such as channels or bosses, reafﬁrming our use of high-level

shape features like segments, symmetries, ridges and valleys to de-

ﬁne planar sections in Section 4.

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作者: 菜刀吻电线 时间: 2012-1-24 23:20
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作者: 晃晃 时间: 2012-2-3 23:24
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作者: tc 时间: 2012-2-11 23:21
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作者: C.R.CAN 时间: 2012-4-24 23:18
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作者: 奇 时间: 2012-6-10 23:22
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作者: 奇 时间: 2012-8-5 00:07
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作者: tc 时间: 2012-8-13 23:58
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作者: 菜刀吻电线 时间: 2012-8-18 23:48
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作者: 晃晃 时间: 2012-9-21 23:30
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