The effect of viewpoint on perceived visual roughness
The effect of viewpoint on perceived visual roughness
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DOI：
10.1167/7.1.1
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发表时间：
2007-01-01
影响因子：
1.8
通讯作者：
Landy, Michael S.
中科院分区：
文献类型：
--
作者：
Ho, Yun-Xian;Maloney, Laurence T.;Landy, Michael S.
在以前的工作中，我们研究了纹理表面的表观粗糙度如何随照明方向而变化。我们发现，观察员表现出系统故障的粗糙度恒定性在整个照明条件下的三角面表面的物理粗糙度被定义为小平面高度的方差。这些失败可能部分是由于场景中的线索混淆了表面粗糙度的变化与照明的变化。这些线索包括：（1）阴影中表面的比例，（2）非阴影部分的平均亮度，（3）非阴影部分亮度的标准差，以及（4）纹理对比度。如果视觉系统依赖于这种粗糙度的“伪线索”，那么它会系统地错误估计表面粗糙度，就像我们的观察者一样，尽管有深度线索，如双眼视差。在这里，我们调查观察者的粗糙度的判断时，照明方向和表面取向是固定的，观察者的观点相对于表面的变化。我们发现了类似的结果模式。观察员表现出模式故障的粗糙度不变的观点的变化，和相当大的一部分，他们的失败可以解释为相同的pseudocues。虽然人类视觉系统表现出一定程度的粗糙度恒定性，我们的研究结果得出的结论是，它并不总是选择正确的线索，为一个给定的视觉任务。
In previous work, we examined how the apparent roughness of a textured surface changed with direction of illumination. We found that observers exhibited systematic failures of roughness constancy across illumination conditions for triangular-faceted surfaces where physical roughness was defined as the variance of facet heights. These failures could be due, in part, to cues in the scene that confound changes in surface roughness with changes in illumination. These cues include the following: (1) the proportion of the surface in shadow, (2) mean luminance of the nonshadowed portion, (3) the standard deviation of the luminance of the nonshadowed portion, and (4) texture contrast. If the visual system relied on such "pseudocues'' to roughness, then it would systematically misestimate surface roughness with changes in illumination much as our observers did despite the availability of depth cues such as binocular disparity. Here, we investigate observers' judgments of roughness when illumination direction and surface orientation are fixed and the observers' viewpoint with respect to the surface changes. We find a similar pattern of results. Observers exhibited patterned failures of roughness constancy with change in viewpoint, and an appreciable part of their failures could be accounted for by the same pseudocues. While the human visual system exhibits some degree of roughness constancy, our results lead to the conclusion that it does not always select the correct cues for a given visual task.