PHOTOMETRIC INVARIANTS RELATED TO SOLID SHAPE
PHOTOMETRIC INVARIANTS RELATED TO SOLID SHAPE
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DOI：
10.1080/713820338
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发表时间：
1980-01-01
期刊：
影响因子：
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通讯作者：
VANDOORN, AJ
中科院分区：
文献类型：
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作者：
KOENDERINK, JJ;VANDOORN, AJ
本文试图确定任意形状的朗伯曲面在任意光照下等光线场的结构不变量。显然，这些不变量在通过明暗对比法感知立体形状方面起着重要作用。我们已经找到了几个这样的不变量。等参线场的拓扑结构由曲面上嵌套的闭合抛物线的集合确定。场的一类重要的驻点依附于这些抛物线。无论光源的位置如何，等光线都以恒定的角度切割抛物线。对于某些正则曲面起伏，明确地给出了等照射线场。
An attempt is made to identify the structural invariants of the field of isophotes on lambertian surfaces of arbitrary shape under arbitrary illumination. It is aprioriclear that such invariants play an important part in the perception of solid shape by means of chiaroscuro. We have found several such invariants. The topological structure of the field of isophotes is determined by the collection of nested, closed parabolic curves on the surface. An important class of stationary points of the field clings to these parabolic lines. The isophotes cut the parabolic lines at a constant angle, irrespective of the location of the light sources. For certain canonical surface undulations the field of isophotes is explicitly given.