Aloimonos J Y
Center for Automation Research, University of Maryland, College Park 20742.
Proc R Soc Lond B Biol Sci. 1989 Oct 23;238(1290):25-37. doi: 10.1098/rspb.1989.0064.
Shading (variations of image intensity) provides an important cue for understanding the shape of three-dimensional surfaces from monocular views. On the other hand, texture (distribution of discontinuities on the surface) is a strong cue for recovering surface orientation by using monocular images. But given the image of an object or scene, what technique should we use to recover the shape of what is image? Resolution of shape from shading requires knowledge of the reflectance of the imaged surface and, usually, the fact that it is smooth (i.e. it shows no discontinuities). Determination of shape from texture requires knowledge of the distribution of surface markings (i.e. discontinuities). One might expect that one method would work when the other does not. I present a theory on how an active observer can determine shape from the image of an object or scene regardless of whether the image is shaded, textured, or both, and without any knowledge of reflectance maps or the distribution of surface markings. The approach is successful because the active observer is able to manipulate the constraints behind the perceptual phenomenon at hand and thus derive a simple solution. Several experimental results are presented with real and synthetic images.
阴影（图像强度变化）为从单眼视图理解三维表面形状提供了重要线索。另一方面，纹理（表面上不连续的分布）是通过使用单眼图像恢复表面方向的有力线索。但是，给定一个物体或场景的图像，我们应该使用什么技术来恢复图像中物体的形状呢？从阴影中解析形状需要了解成像表面的反射率，并且通常需要知道它是光滑的（即没有不连续）这一事实。从纹理确定形状需要了解表面标记的分布（即不连续）。人们可能期望一种方法在另一种方法不适用时起作用。我提出了一种理论，说明主动观察者如何能够从物体或场景的图像中确定形状，而不管图像是有阴影、有纹理还是两者皆有，并且无需任何关于反射率图或表面标记分布的知识。这种方法之所以成功，是因为主动观察者能够操纵手头感知现象背后的约束条件，从而得出一个简单的解决方案。文中展示了一些使用真实图像和合成图像的实验结果。
