We propose an interactive contour extraction method inspired by a skill often adopted in sketching: an artist usually sketches an object by first drawing lots of short, directional, and redundant strokes, then following these small strokes to draw the final outline of the object. Our method simulates this process. To extract a contour, our method relies on user interaction, which provides us with a narrow band containing the target contour. Then, we densely sample sub-bands from the whole band, with each sub-band containing a local segment of the target contour. We design a curve-centered coordinate system in which a dynamic programming algorithm is proposed to extract the local segment in each sub-band. The local segment is guaranteed to be as evident and smooth as possible, to mimic the strokes sketched by the artist. Finally, we integrate all local segments of all sub-bands together to obtain the whole target contour based on the weighted principal component analysis. Our method can extract high-quality object contours due to the dense validations among local segments. That is, even if one segment deviates from the right location, several other segments in its local neighborhood can correct it in the integration stage. Both quantitative experiments and a user study demonstrate the effectiveness of the proposed method.

中文翻译：

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通过类似草图的密集验证优化进行交互式轮廓提取

我们提出了一种交互式轮廓提取方法，其灵感来自于素描中经常采用的一项技能：艺术家通常通过首先绘制大量短的、定向的和冗余的笔触来绘制对象，然后按照这些小笔画绘制对象的最终轮廓。我们的方法模拟了这个过程。为了提取轮廓，我们的方法依赖于用户交互，这为我们提供了一个包含目标轮廓的窄带。然后，我们从整个波段中密集采样子波段，每个子波段包含目标轮廓的局部段。我们设计了一个以曲线为中心的坐标系，其中提出了一种动态规划算法来提取每个子带中的局部线段。保证局部部分尽可能明显和平滑，以模仿艺术家绘制的笔触。最后，我们基于加权主成分分析将所有子带的所有局部段整合在一起以获得整个目标轮廓。由于局部段之间的密集验证，我们的方法可以提取高质量的对象轮廓。也就是说，即使一个段偏离了正确的位置，其本地邻域中的其他几个段也可以在集成阶段对其进行纠正。定量实验和用户研究都证明了所提出方法的有效性。其本地邻域中的其他几个部分可以在集成阶段对其进行纠正。定量实验和用户研究都证明了所提出方法的有效性。其本地邻域中的其他几个部分可以在集成阶段对其进行纠正。定量实验和用户研究都证明了所提出方法的有效性。