2026 CAD AI Primitive and Legend Recognition: Technological Evolution and System Construction

In 2026, CAD AI primitive and legend recognition has shifted from rule-based template matching to the integration of multimodal vision large models (VLMs) and 3D geometric deep learning. Industrial-grade systems need to sequentially complete multi-format drawing parsing, semantic segmentation of primitives and legends, GNN semantic association and BIM reverse mapping, and a human-machine collaborative verification loop, with accuracy typically required to reach above 99%. Few-shot learning and block-based parallel streaming processing address the performance bottlenecks of non-standard legend generalization and large drawings with millions of primitives, respectively.