Are optical distortions used as a cue for material properties of thick transparent objects?
Are optical distortions used as a cue for material properties of thick transparent objects?
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DOI：
10.1167/14.14.2
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发表时间：
2014-01-01
影响因子：
1.8
通讯作者：
Faul, Franz
中科院分区：
文献类型：
--
作者：
Schlueter, Nick;Faul, Franz
Fleming，Jakel和Maloney（2011）要求受试者通过调整折射率来匹配照片真实场景中厚而透明的透明物体的感知材料属性。他们发现了标准和测试对象之间的近似对应关系，但也有很大的系统偏差。然而，他们得出结论认为，估计的折射率被用作透光物体材料特性的指标，并强调了物体引起的背景失真在这一过程中的作用。然而，这似乎不可信，因为从畸变中推断折射率的必要信息-例如，物体的确切形状和厚度，背景距离和未畸变的背景-在他们的情况下是不可用的。一个更合理的替代解释是，受试者没有匹配估计的折射率，而是直接基于与背景失真或镜面反射相关的图像属性进行简单的相似性匹配。我们在一个类似的匹配实验中测试了这一假设，在该实验中，可以预测基于背景失真的相似性匹配和基于镜面反射的相似性匹配的折射率。我们的受试者总是在这两个预测之间选择一个值。镜面反射一旦变得清晰可见，就会成为主要因素。我们的研究结果是兼容的假设，即受试者试图找到一个妥协之间的两个基于图像的相似性标准。它们似乎与根据折射率的内部估计进行匹配的假设不一致。
Fleming, Jakel, and Maloney (2011) asked subjects to match perceived material properties of thick, clear transparent objects in photo-realistic scenes by adjusting the refractive index. They found approximate correspondence between standard and test objects but also large systematic deviations. Nevertheless, they concluded that estimated refraction is used as an indicator for material properties of light-transmitting objects and emphasized the role of object-induced background distortions in this process. This, however, seems not plausible, because the necessary information for inferring the refractive index from distortions-for example, the object's exact shape and thickness, its background distance, and the undistorted background- was not available in their situation. A more plausible alternative explanation is that the subjects did not match estimated refractive indices, but instead performed simple similarity matches based directly on image attributes related to background distortions or specular reflections. We tested this hypothesis in a similar matching experiment in which it was possible to predict the refractive index for a similarity match based on background distortions and for a similarity match based on specular reflections. Our subjects always chose a value between these two predictions. The specular reflection tends to be the dominant factor as soon as it becomes clearly noticeable. Our findings are compatible with the assumption that the subjects tried to find a compromise between two image-based similarity criteria. They do not seem to be consistent with the assumption that the matches are made on the basis of internal estimates of refractive indices.