J Vis. 2020 May 11;20(5):2. doi: 10.1167/jov.20.5.2.
The present research was designed to examine how patterns of illumination influence the perceptual categorization of metal, shiny black, and shiny white materials. The stimuli depicted three possible objects that were illuminated by five possible high-dynamic-range imaging light maps, which varied in their overall distributions of illuminant directions and intensities. The surfaces included a low roughness chrome material, a shiny black material, and a shiny white material with both diffuse and specular components. Observers rated each stimulus by adjusting four sliders to indicate their confidence that the depicted material was metal, shiny black, shiny white, or something else, and these adjustments were constrained so that the sum of all four settings was always 100%. The results revealed that the metal and shiny black categories are easily confused. For example, metal materials with low intensity light maps or a narrow range of illuminant directions are often judged as shiny black, whereas shiny black materials with high intensity light maps or a wide range of illuminant directions are often judged as metal. To discover the visual information on which these judgements are based, we measured several possible image statistics, and we found two that were highly correlated with the observers' confidence ratings in appropriate contexts. We also performed a spherical harmonic analysis on the different light maps to quantitatively predict how they would bias observers' judgments of metal and shiny black surfaces.
本研究旨在探讨照明模式如何影响金属、闪亮黑色和闪亮白色材料的知觉分类。刺激物描绘了三个可能的物体，它们被五个可能的高动态范围成像光照图照亮，这些光照图在光照方向和强度的整体分布上有所不同。表面包括低粗糙度的铬材料、闪亮的黑色材料和具有漫反射和镜面反射成分的闪亮白色材料。观察者通过调整四个滑块来对每个刺激物进行评分，以表明他们对所描绘材料是金属、闪亮黑色、闪亮白色还是其他材料的置信度，并且这些调整受到限制，使得所有四个设置的总和始终为 100%。结果表明，金属和闪亮黑色类别很容易混淆。例如，光照图强度低或光照方向范围窄的金属材料通常被判断为闪亮黑色，而光照图强度高或光照方向范围宽的闪亮黑色材料通常被判断为金属。为了发现这些判断所依据的视觉信息，我们测量了几个可能的图像统计数据，并发现了两个在适当的上下文中与观察者的置信度评分高度相关的统计数据。我们还对不同的光照图进行了球谐分析，以定量预测它们将如何影响观察者对金属和闪亮黑色表面的判断。
