基于格式塔心理学和Euler spiral的轮廓修复算法

现有的轮廓修复方法假设已知遮挡发生的位置, 且未考虑人类认知特性。针对该问题, 提出一种结构较完整的轮廓修复方法。算法首先检测T型节点确定遮挡发生的位置; 根据格式塔心理学的完形法则提出组合约束条件, 据此将T型节点进行组合。对平滑轮廓遮挡, 基于Euler spiral, 并以曲率变化最小作为能量最小化准则, 修复局部缺失的轮廓; 对角点轮廓遮挡, 利用过角点的两条曲线的可见部分构造两条Euler spiral, 根据Euler spiral的扩展性对构造的两条Euler spiral进行延拓并求交, 从而修复角点遮挡轮廓。方法能自动确定遮挡发生的位置, 能够对T型节点进行正确组合, 使轮廓修复更符合人类视觉感知; 对角点轮廓遮挡采用Euler spiral的扩展性进行修复, 能克服角点轮廓修复仅适合于修复轮廓为直线或圆弧的规则物体。应用模拟图像和真实图像验证了方法的有效性。

Gestalt psychology and Euler spiral for contour completion

The existing contour completion methods assume known the positions of occlusion, and do not consider the human cognitive characteristics. To solve these problems, this paper proposed a more complete contour completion method. The algorithm firstly detected T-junctions to locate the occlusion; then proposed the combined constraint conditions based on laws of organization in Gestalt psychology, combined T-junctions using the above conditions. Finally, it investigated the contour completion in two kinds. For smooth contour, it completed by Euler spiral. It considered curvature variation minimum as energy minimization criterion. For occluded corner contour, it constructed two Euler spiral using the visible part of the two curves which composed the corner point. The constructed two Euler spirals extended and intersected with each other according to the extensible of Euler spiral. This method can automatically locate the occlusion by detecting T-junctions; the contour completion can more correspond with human visual perception through correct combination of T-junction. The completion of occluded corner contour can overcome the completion of occluded corner contour be only suitable for regular objects whose contour are lines or arcs. The results of synthetic images and real images show the efficiency of the algorithm.