Kersten D
Psychology Department, University of Minnesota, Minneapolis 55455, USA.
Philos Trans R Soc Lond B Biol Sci. 1997 Aug 29;352(1358):1155-63. doi: 10.1098/rstb.1997.0099.
The central problems of vision are often divided into object identification and localization. Object identification, at least at fine levels of discrimination, may require the application of top-down knowledge to resolve ambiguous image information. Utilizing top-down knowledge, however, may require the initial rapid access of abstract object categories based on low-level image cues. Does object localization require a different set of operating principles than object identification or is category determination also part of the perception of depth and spatial layout? Three-dimensional graphics movies of objects and their cast shadows are used to argue that identifying perceptual categories is important for determining the relative depths of objects. Processes that can identify the causal class (e.g. the kind of material) that generates the image data can provide information to determine the spatial relationships between surfaces. Changes in the blurriness of an edge may be characteristically associated with shadows caused by relative motion between two surfaces. The early identification of abstract events such as moving object/shadow pairs may also be important for depth from shadows. Knowledge of how correlated motion in the image relates to an object and its shadow may provide a reliable cue to access such event categories.
视觉的核心问题通常分为目标识别和定位。目标识别，至少在精细的辨别层面，可能需要运用自上而下的知识来解析模糊的图像信息。然而，运用自上而下的知识可能需要基于低级图像线索首先快速获取抽象的目标类别。目标定位所需的操作原则与目标识别不同，还是类别确定也是深度和空间布局感知的一部分呢？利用物体及其投射阴影的三维图形电影来论证，识别感知类别对于确定物体的相对深度很重要。能够识别生成图像数据的因果类别（例如材料种类）的过程可以提供信息来确定表面之间的空间关系。边缘模糊度的变化可能与两个表面之间相对运动产生的阴影有典型关联。诸如移动物体/阴影对之类的抽象事件的早期识别对于从阴影中感知深度也可能很重要。关于图像中的相关运动如何与物体及其阴影相关的知识可能提供一个可靠的线索来获取此类事件类别。
