Learning to use illumination gradients as an unambiguous cue to three dimensional shape.
Learning to use illumination gradients as an unambiguous cue to three dimensional shape.
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DOI：
10.1371/journal.pone.0035950
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Bloj M
中科院分区：
文献类型：
--
作者：
Harding G;Harris JM;Bloj M
图像中的亮度和颜色梯度是物体形状、材质和照明之间复杂相互作用的结果。因此，使用这种变化来推断物体形状或表面颜色对于视觉系统来说是一个难题。我们知道，物体形状的变化会影响其感知的颜色，并且阴影渐变会赋予形状感。在这里，我们研究视觉系统是否能够有效地利用这些梯度作为形状感知的提示，即使在没有其他提示的情况下也是如此。我们测试了折叠卡片对象的形状感知，其中包含阴影形式的照明梯度和更微妙的效果（例如相互反射）。我们的结果表明观察者能够使用梯度做出一致的形状判断。为了做到这一点，观察者必须有机会了解有关照明和场景的适当假设。使用各种不同的训练条件，我们证明学习可以快速发生并且只需要粗略的信息。我们还确定学习并不能提供梯度和形状之间的简单映射；相反，学习会导致获得有关照明和场景参数的假设，随后允许将梯度用作形状提示。对于表现出非常不同的阴影的物体的凸面和凹面版本，感知的形状是一致的，并且也类似于轮廓所传递的形状，这是与形状很大程度上无关的线索。总的来说，我们的结果表明，尽管梯度不如其他一些线索可靠，但可以快速评估梯度和形状之间的关系，因此可以有效地将梯度用作视觉形状线索。
The luminance and colour gradients across an image are the result of complex interactions between object shape, material and illumination. Using such variations to infer object shape or surface colour is therefore a difficult problem for the visual system. We know that changes to the shape of an object can affect its perceived colour, and that shading gradients confer a sense of shape. Here we investigate if the visual system is able to effectively utilise these gradients as a cue to shape perception, even when additional cues are not available. We tested shape perception of a folded card object that contained illumination gradients in the form of shading and more subtle effects such as inter-reflections. Our results suggest that observers are able to use the gradients to make consistent shape judgements. In order to do this, observers must be given the opportunity to learn suitable assumptions about the lighting and scene. Using a variety of different training conditions, we demonstrate that learning can occur quickly and requires only coarse information. We also establish that learning does not deliver a trivial mapping between gradient and shape; rather learning leads to the acquisition of assumptions about lighting and scene parameters that subsequently allow for gradients to be used as a shape cue. The perceived shape is shown to be consistent for convex and concave versions of the object that exhibit very different shading, and also similar to that delivered by outline, a largely unrelated cue to shape. Overall our results indicate that, although gradients are less reliable than some other cues, the relationship between gradients and shape can be quickly assessed and the gradients therefore used effectively as a visual shape cue.
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DOI：
10.3758/bf03205268
发表时间：
1993-09-01
期刊：
PERCEPTION & PSYCHOPHYSICS
影响因子：
--
作者：
ERENS, RGF;KAPPERS, AML;KOENDERINK, JJ
通讯作者：
KOENDERINK, JJ
DOI：
10.1080/713820338
发表时间：
1980-01-01
期刊：
OPTICA ACTA
影响因子：
--
作者：
KOENDERINK, JJ;VANDOORN, AJ
通讯作者：
VANDOORN, AJ
影响因子：
1.8
作者：
Lovell, Paul G.;Bloj, Marina;Harris, Julie M.
通讯作者：
Harris, Julie M.
影响因子：
64.8
作者：
Bloj, MG;Kersten, D;Hurlbert, AC
通讯作者：
Hurlbert, AC
影响因子：
19.5
作者：
Belhumeur, PN;Kriegman, DJ;Yuille, AL
通讯作者：
Yuille, AL