Slices: A Shape-proxy Based on Planar Sections

晃晃

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.



全文请下载附件：

菜刀吻电线

祝你新的一年:生活越来越好，脾气越来越小，经济再往上搞，基本解决温饱，顿顿保证没草，家中肉多狼少，饭菜不用再讨，也有异性来骚扰。

C.R.CAN

美酒令人回味，音乐让人陶醉，好书百读不悔，情意形影相随，节日问候最可贵。又到年终岁尾，愿你幸福健康作陪，笑得合不拢嘴，预祝春节快乐！

晃晃

先顶上去，偶要高亮加精鸟！

tc

已阵亡的 蝶 随 风 舞 说过  偶尔按一下 CTRL A 会发现 世界还有另一面

C.R.CAN

好可爱的字,学习了

奇

我就看看，我不说话

奇

谢谢楼主，真是太实用了

tc

发了那么多，我都不知道该用哪个给你回帖了，呵呵

菜刀吻电线

先顶上去，偶要高亮加精鸟！