ESTIMATING LOCAL SHAPE FROM SHADING IN THE PRESENCE OF GLOBAL SHADING
ESTIMATING LOCAL SHAPE FROM SHADING IN THE PRESENCE OF GLOBAL SHADING
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DOI：
10.3758/bf03205268
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发表时间：
1993-09-01
期刊：
影响因子：
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通讯作者：
KOENDERINK, JJ
中科院分区：
文献类型：
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作者：
ERENS, RGF;KAPPERS, AML;KOENDERINK, JJ
理论上，全局明暗处理可以帮助从明暗处理估计局部表面结构(例如，指定光源方向)。经验上，我们不知道人类观察者是否结合了局部阴影和全局阴影给出的信息来估计局部形状，观察者必须在有或没有背景表面提供的全局阴影信息的情况下指示局部细长扰动的方向。我们的心理物理结果表明：1.在没有全局阴影信息的情况下，观察者并不能更准确地估计局部扰动的方向。2.响应很大程度上取决于光源方向和观察方向之间的倾角。对于20度的倾斜，观察者或多或少地指示了局部脊线的方向；然而，对于40度的倾斜，他们要么指示光源的方向，要么指示接近扰动阴影边缘的方向。大多数受试者都表现出这些行为的某种组合。这一行为不会被全局阴影信息改变。我们的结论是，在我们的范例中，全局阴影信息并不有助于局部形状的估计。
In theory, global shading may help with the estimation of local surface structure from shading (e.g., in specifying the illuminant direction). Empirically, we do not know whether human observers combine the information given by the local and global shading to estimate local shape.Observers had to indicate the orientation of a local elongated perturbation with or without global shading information provided by a background surface. Our psychophysical results show the following: 1. Observers do not estimate the orientation of the local perturbation more accurately with global shading information than they do in the absence of such information. 2. Responses depend dramatically on the inclination between the illuminant direction and the viewing direction. For an inclination of 20-degrees, observers indicate more or less the orientation of the local ridge; however, for an inclination of 40-degrees, they indicate either the direction of the illuminant or an orientation close to the shadow edge of the perturbation. Most subjects show some combination of these behaviors. This behavior is not altered by global shading information.We conclude that in our paradigm, global shading information does not aid the estimation of local shape.