Topology-Preserving Data Augmentation for Ring-Type Polygon Annotations
This work addresses a specific issue in segmentation pipelines for structured domains, but it is incremental as it builds on existing augmentation methods by adding a repair mechanism.
The paper tackles the problem of preserving cyclic connectivity in ring-type polygon annotations during geometric data augmentation, which is crucial for structured domains like architectural floorplan analysis. The result is an order-preserving strategy that reliably restores connectivity, achieving near-perfect Cyclic Adjacency Preservation (CAP) across augmentations.
Geometric data augmentation is widely used in segmentation pipelines and typically assumes that polygon annotations represent simply connected regions. However, in structured domains such as architectural floorplan analysis, ring-type regions are often encoded as a single cyclic polygon chain connecting outer and inner boundaries. During augmentation, clipping operations may remove intermediate vertices and disrupt this cyclic connectivity, breaking the structural relationship between the boundaries. In this work, we introduce an order-preserving polygon augmentation strategy that performs transformations in mask space and then projects surviving vertices back into index-space to restore adjacency relations. This repair maintains the original traversal order of the polygon and preserves topological consistency with minimal computational overhead. Experiments demonstrate that the approach reliably restores connectivity, achieving near-perfect Cyclic Adjacency Preservation (CAP) across both single and compound augmentations.