HierCAD: Hierarchical Text-to-CAD Design via Structure Alignment and Parameter Grounding

2026-07-13

AI Summary

Existing text-to-CAD generation methods struggle to maintain structural consistency and accurately realize geometric parameters in complex designs. This work proposes HierCAD, a framework that formulates CAD generation as a hierarchical reasoning process: high-level object-wise procedural reasoning is coupled with low-level part-wise topological reasoning. By integrating a joint learning mechanism for structural alignment and parameter realization—augmented with large language models, CAD construction tree decomposition, parameter perturbation, and ranking-based supervision—the approach effectively mitigates shortcut learning. Experimental results demonstrate that HierCAD outperforms state-of-the-art methods on both CAD sequence generation and reconstruction tasks, achieving significant improvements in structural fidelity and parameter accuracy.

Abstract

Recent text-to-CAD approaches have shown promising results by leveraging large language models, but they often struggle with maintaining structural consistency in complex designs and accurately grounding geometric parameters. To address these issues, we propose HierCAD, a hierarchical text-to-CAD framework that improves both structural reasoning and parameter prediction. HierCAD reformulates CAD generation as progressive reasoning by decomposing CAD construction trees into object-level procedural reasoning and part-level topology reasoning trajectories. To further improve generation fidelity, we introduce a unified Structure Alignment and Parameter Grounding (SAPG) learning strategy. Structure alignment aligns topology reasoning trajectories with their corresponding parametric CAD spans, while parameter grounding mitigates shortcut learning through structure-preserving parameter perturbations and ranking-based supervision. Experiments demonstrate that HierCAD outperforms prior state-of-the-art methods on both CAD sequence generation and reconstructed CAD model evaluation. Our code is available at https://github.com/Collab-Gen/HierCAD.

Problem

• text-to-CAD
• structural consistency
• parameter grounding
• geometric parameters
• CAD generation

Innovation

• Hierarchical text-to-CAD
• Structure Alignment
• Parameter Grounding
• Procedural Reasoning
• Topology Reasoning