We present a novel freehand sketch beautification method, which takes as input a freely drawn sketch of a man-made object and automatically beautifies it both geometrically and structurally. Beautifying a sketch is challenging because of its highly abstract and heavily diverse drawing manner. Existing methods are usually confined to the distribution of their limited training samples and thus cannot beautify freely drawn sketches with rich variations. To address this challenge, we adopt a divide-and-combine strategy. Specifically, we first parse an input sketch into semantic components, beautify individual components by a learned part beautification module based on part-level implicit manifolds, and then reassemble the beautified components through a structure beautification module. With this strategy, our method can go beyond the training samples and handle novel freehand sketches. We demonstrate the effectiveness of our system with extensive experiments and a perceptive study.

翻译：我们提出了一种新颖的草图美化方法，该方法以自由绘制的人造物体草图作为输入，并自动从几何和结构层面对其进行美化。由于草图具有高度抽象且绘制方式极为多样化的特点，其美化工作颇具挑战性。现有方法通常受限于有限训练样本的分布，因此无法对具有丰富多样性的自由绘制草图进行美化。为应对这一挑战，我们采用分治策略。具体而言，我们首先将输入草图解析为语义部件，通过基于部件级隐式流形的学习型部件美化模块对单个部件进行美化，随后通过结构美化模块对美化后的部件进行重组。凭借此策略，我们的方法能够超越训练样本的局限，处理新颖的自由手绘草图。我们通过大量实验和感知研究证明了该系统的有效性。