Symmetry detection, especially partial and extrinsic symmetry, is essential for various downstream tasks, like 3D geometry completion, segmentation, compression and structure-aware shape encoding or generation. In order to detect partial extrinsic symmetries, we propose to learn rotation, reflection, translation and scale invariant local shape features for geodesic point cloud patches via contrastive learning, which are robust across multiple classes and generalize over different datasets. We show that our approach is able to extract multiple valid solutions for this ambiguous problem. Furthermore, we introduce a novel benchmark test for partial extrinsic symmetry detection to evaluate our method. Lastly, we incorporate the detected symmetries together with a region growing algorithm to demonstrate a downstream task with the goal of computing symmetry-aware partitions of 3D shapes. To our knowledge, we are the first to propose a self-supervised data-driven method for partial extrinsic symmetry detection.

对于各种下游任务（如3D几何完成、分割、压缩和结构感知形状编码或生成），对称性检测，特别是局部和外在对称性，是至关重要的。为了检测局部外在对称性，我们提出通过对比学习来学习旋转、反射、平移和尺度不变的局部形状特征，这些特征在多个类别和不同数据集上都具有鲁棒性和泛化性。我们展示了我们的方法能够提取多个正确解决方案，以解决这个模糊的问题。此外，我们引入了一个新的基准测试，用于评估我们的局部外在对称性检测方法。最后，我们将检测到的对称性与区域增长算法相结合，以实现一个下游任务，即计算对称感知的3D形状的划分。据我们所知，我们是第一个提出自监督数据驱动局部外在对称性检测方法的人。

基于对比学习和地理点云块的三维几何部分对称性检测