The Perception of Surface Material

物体或场景的视觉特性如何影响人的视觉感知是认知科学中的一个基本问题。拟议的研究涉及表面的视觉特性，可以揭示许多对决策很重要的特征，例如物质的身份，物品的清洁度或照片的真实性。人类通过分析表面材料反射的光来做出这些判断。拟议的研究将探讨如何实现这一点。光亮的材料，如抛光的金属，光泽涂料，光滑的塑料和涂漆的木材产生明亮的反射光源照亮他们。人类非常善于区分这些反射与其他原因的亮点，如白色哑光油漆。反射是视图相关的，这意味着它们在表面上的表观位置根据观察眼睛的位置而变化。由于这种视图依赖性，反射通常看起来位于表面之下。拟议的研究将研究反射的明显位置如何影响人类对材料的判断。研究人员将对许多类型材料的反射特性进行理论研究，并对人类如何利用这些特性来识别材料进行实验研究。研究人员还将开发新的计算机图形算法和新的显示技术，以实现从真实材料反射的真实呈现。这项工作将对基础科学和若干应用作出重大贡献。一个重要的应用涉及工业如何描述材料的视觉特性。目前，油漆、塑料和家具的制造商使用一维的外观尺度，如光泽度，和廉价的外观测量设备，如光泽度计，来按"光泽度"对饰面进行分类。"即使不同的材料产生不同的反射，它们也可以具有相同的光泽度。研究人员将确定具有相同光泽度的材料实际上看起来是否相同。结果可能会影响行业测量和评估材料的方式。另一个重要的应用涉及人们如何区分计算机生成的图像和真实的图像。这不仅对电影和计算机图形工业，而且对法医学都有重要的影响。首席研究员与数字取证专家合作，将探索计算机生成的和真实的人的皮肤光散射模式以及相关的视差特性是否有助于区分假图像和真实的图像。

How the visual properties of an object or scene affect human visual perception is a fundamental question in cognitive science. The proposed research is concerned with the visual properties of surfaces, which can reveal many characteristics important to decision-making, such as the identity of a substance, the cleanliness of an item, or the authenticity of a photograph. Humans make these judgments by analyzing the light reflected from surface materials. The proposed research examines how this is accomplished. Shiny materials like polished metal, gloss paint, smooth plastic, and varnished wood yield bright reflections of the light sources that illuminate them. Humans are quite adept at distinguishing those reflections from other causes of bright spots, such as white matte paint. Reflections are view dependent, meaning that their apparent position on the surface changes depending on the location of the viewing eye. Because of this view dependence, the reflection usually appears to lie beneath the surface. The proposed research will examine how the apparent position of reflections affects human judgments of material. The investigators will conduct theoretical work on the properties of reflections from many types of materials and experimental work on how well humans are able to use these properties to identify material. The investigators will also develop new computer graphics algorithms and a new display technique to allow realistic presentation of reflections from realistic materials. The work will contribute significantly to basic science and to several applications. One important application concerns how industry describes the visual properties of materials. Currently, manufacturers of paint, plastics, and furniture use one-dimensional scales of appearance, such as gloss, and inexpensive appearance measurement devices, such as glossmeters, to categorize finishes by "gloss level." Very different materials can have the same gloss level even though they produce very different reflections. The investigators will determine whether materials with the same gloss level actually look the same. The results could affect the way industry measures and assesses material. Another important application concerns how people distinguish between computer-generated and real images. This has important implications, not only for the motion picture and computer graphics industries, but also for forensic sciences. The principal investigator, in collaboration with an expert in digital forensics, will explore whether the pattern of light dispersal from human skin in computer-generated and real people, and the associated parallax properties, can aid in distinguishing fake from real images.