INTERPRETING LINE DRAWINGS OF CURVED OBJECTS
INTERPRETING LINE DRAWINGS OF CURVED OBJECTS
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DOI：
10.1007/bf00128527
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发表时间：
1987-01-01
影响因子：
19.5
通讯作者：
MALIK, J
中科院分区：
文献类型：
--
作者：
MALIK, J
在本文中，我们研究了解释由不透明规则固体物体组成的场景线条图的问题，这些物体由分段光滑表面界定，表面上没有标记或纹理。假设线条图是通过在一般视点下对这样的场景进行正投影而形成的，线条图没有错误，并且不存在由于阴影或镜面反射而导致的线条。我们的定义隐含地排除了薄片、线和锥体的顶点。线条图解释的一个主要组成部分是线条标记。通过线标记，我们的意思是（a）将每条图像曲线分类为对应于场景中的深度或方向不连续性，以及（b）对每种不连续性进行进一步子分类。对于深度不连续性，我们确定它是边缘（表面上视线与表面相切的点的轨迹）还是遮挡边缘（表面的切平面不连续性）。对于方向不连续性，我们确定它是否对应于凸边或凹边。本文提出了第一个数学上严格的方案，用于标记所描述场景类别的线条图。以前对包含弯曲物体的场景的线图进行标记的方案是启发式的、不完整的，并且缺乏适当的数学论证。通过分析分段光滑表面上不同类型的点的邻域投影，我们能够对线图中不同类型的连接点的所有局部标记可能性进行分类。开发了一种算法，利用该目录来确定线条图的所有合法标签。使用局部最小复杂度规则（在每个顶点选择与在顶点相遇的最小面数相对应的标签）来修剪高度反直觉的解释。标签方案在许多线条图上实施和测试。获得的标签很少，而且大体上符合人类的解释。
In this paper, we study the problem of interpreting line drawings of scenes composed of opaque regular solid objects bounded by piecewise smooth surfaces with no markings or texture on them. It is assumed that the line drawing has been formed by orthographic projection of such a scene under general viewpoint, that the line drawing is error free, and that there are no lines due to shadows or specularities. Our definition implicitly excludes laminae, wires, and the apices of cones.A major component of the interpretation of line drawings is linelabelling. By line labelling we mean (a) classification of each image curve as corresponding to either a depth or orientation discontinuity in the scene, and (b) further subclassification of each kind of discontinuity. For a depth discontinuity we determine whether it is alimb—a locus of points on the surface where the line of sight is tangent to the surface—or an occludingedge—a tangent plane discontinuity of the surface. For an orientation discontinuity, we determine whether it corresponds to a convex or concave edge. This paper presents the first mathematically rigorous scheme for labelling line drawings of the class of scenes described. Previous schemes for labelling line drawings of scenes containing curved objects were heuristic, incomplete, and lacked proper mathematical justification.By analyzing the projection of the neighborhoods of different kinds of points on a piecewise smooth surface, we are able to catalog all local labelling possibilities for the different types of junctions in a line drawing. An algorithm is developed which utilizes this catalog to determine all legal labellings of the line drawing. A local minimum complexity rule—at each vertex select those labellings which correspond to the minimum number of faces meeting at the vertex—is used in order to prune highly counter-intuitive interpretations. The labelling scheme was implemented and tested on a number of line drawings. The labellings obtained are few and by and large in accordance with human interpretations.