🤖 AI Summary
This paper addresses the problem that rotation symmetry detection in 2D images suffers from viewpoint distortion, leading to 3D geometric inconsistency. To tackle this, we propose the first end-to-end differentiable framework explicitly embedding 3D geometric priors—namely, equal edge lengths and equal interior angles. Our method models symmetry via 3D vertex regression followed by orthogonal projection, explicitly enforcing structural consistency of both the rotation center and supporting vertices in 3D space. A geometry-aware loss function jointly optimizes these constraints. Unlike purely 2D modeling approaches, our framework ensures geometric integrity from the outset. On the DENDI dataset, our method achieves a substantial improvement in rotation axis detection average precision (AP) over state-of-the-art methods. Ablation studies quantify the contribution of the 3D geometric priors at +12.7% AP, demonstrating their effectiveness in mitigating performance degradation induced by viewpoint distortion.
📝 Abstract
Symmetry plays a vital role in understanding structural patterns, aiding object recognition and scene interpretation. This paper focuses on rotation symmetry, where objects remain unchanged when rotated around a central axis, requiring detection of rotation centers and supporting vertices. Traditional methods relied on hand-crafted feature matching, while recent segmentation models based on convolutional neural networks detect rotation centers but struggle with 3D geometric consistency due to viewpoint distortions. To overcome this, we propose a model that directly predicts rotation centers and vertices in 3D space and projects the results back to 2D while preserving structural integrity. By incorporating a vertex reconstruction stage enforcing 3D geometric priors -- such as equal side lengths and interior angles -- our model enhances robustness and accuracy. Experiments on the DENDI dataset show superior performance in rotation axis detection and validate the impact of 3D priors through ablation studies.