Johnston A, Passmore P J
Department of Psychology, University College London, England.
Vision Res. 1994 Nov;34(22):3005-12. doi: 10.1016/0042-6989(94)90273-9.
Marr [(1982) Vision, San Francisco, Calif.: Freeman] proposed that we represent surface geometry in terms of a viewer-centred description of surface orientation and distance. This description is computed by a range of independent processing systems which take as input particular kinds of information present in images, like surface texture, shading, retinal disparity and motion parallax. The outputs of these modules are integrated in order to provide a unitary representation of the layout of visible surfaces. Higher order properties of surface geometry, like surface curvature, might be computed from this symbolic representation or might be encoded independently from the visual information available at the retinae. We measured surface slant and surface curvature discrimination thresholds for surface patches defined by shading, texture and retinal disparity as a function of the elevation of the illumination. We found that observers judgements about the curvature of local surface patches were too precise to be based on a symbolic representation of surface orientation and we conclude that surface curvature is computed directly from depth cues present in the retinal images.
马尔[(1982年)《视觉》，加利福尼亚州旧金山：弗里曼出版社]提出，我们根据以观察者为中心的表面方向和距离描述来表示表面几何形状。这种描述由一系列独立的处理系统计算得出，这些系统将图像中存在的特定类型信息作为输入，如表面纹理、阴影、视网膜视差和运动视差。这些模块的输出进行整合，以便提供可见表面布局的统一表示。表面几何形状的高阶属性，如表面曲率，可能从这种符号表示中计算得出，也可能独立于视网膜上可用的视觉信息进行编码。我们测量了由阴影、纹理和视网膜视差定义的表面斑块的表面倾斜度和表面曲率辨别阈值，作为光照高度的函数。我们发现，观察者对局部表面斑块曲率的判断过于精确，无法基于表面方向的符号表示，并且我们得出结论，表面曲率是直接从视网膜图像中存在的深度线索计算得出的。
