Zhang Fan, de Ridder Huib, Pont Sylvia C
Perceptual Intelligence Laboratory, Industrial Design Engineering, Delft University of Technology, The Netherlands.
J Vis. 2018 Oct 1;18(11):11. doi: 10.1167/18.11.11.
To better understand the interactions between material perception and light perception, we further developed our material probe MatMix 1.0 into MixIM 1.0, which allows optical mixing of canonical lighting modes. We selected three canonical lighting modes (ambient, focus, and brilliance) and created scenes to represent the three illuminations. Together with four canonical material modes (matte, velvety, specular, glittery), this resulted in 12 basis images (the "bird set"). These images were optically mixed in our probing method. Three experiments were conducted with different groups of observers. In Experiment 1, observers were instructed to manipulate MixIM 1.0 and match optically mixed lighting modes while discounting the materials. In Experiment 2, observers were shown a pair of stimuli and instructed to simultaneously judge whether the materials and lightings were the same or different in a four-category discrimination task. In Experiment 3, observers performed both the matching and discrimination tasks in which only the ambient and focus light were implemented. Overall, the matching and discrimination results were comparable as (a) robust asymmetric perceptual confounds were found and confirmed in both types of tasks, (b) performances were consistent and all above chance levels, and (c) observers had higher sensitivities to our canonical materials than to our canonical lightings. The latter result may be explained in terms of a generic insensitivity for naturally occurring variations in light conditions. Our findings suggest that midlevel image features are more robust across different materials than across different lightings and, thus, more diagnostic for materials than for lightings, causing the asymmetric perceptual confounds.
为了更好地理解材质感知与光照感知之间的相互作用，我们将材质探测器MatMix 1.0进一步升级为MixIM 1.0，它能够对标准光照模式进行光学混合。我们选择了三种标准光照模式（环境光、聚焦光和高光），并创建场景来呈现这三种光照。再结合四种标准材质模式（哑光材质、天鹅绒材质、镜面材质、闪光材质），这样就得到了12张基础图像（即“鸟类图像集”）。这些图像通过我们的探测方法进行光学混合。我们对不同组的观察者进行了三项实验。在实验1中，观察者被要求操作MixIM 1.0，匹配光学混合后的光照模式，同时忽略材质因素。在实验2中，向观察者展示一对刺激物，并要求他们在四类辨别任务中同时判断材质和光照是否相同或不同。在实验3中，观察者同时执行匹配任务和辨别任务，其中只采用环境光和聚焦光。总体而言，匹配和辨别结果具有可比性，原因如下：（a）在这两种类型的任务中都发现并证实了强烈的不对称感知混淆；（b）表现一致且均高于随机水平；（c）观察者对我们的标准材质比对标准光照更敏感。后一个结果可以用对自然光照条件变化的普遍不敏感来解释。我们的研究结果表明，中级图像特征在不同材质之间比在不同光照之间更稳健，因此，对材质的诊断性比对光照更强，从而导致了不对称感知混淆。
