Semantic Direct Modeling

Abstract: Current direct modeling systems limit users to low-level interactions with vertices, edges, and faces, forcing designers to manage detailed geometric elements rather than focusing on high-level design intent. This paper introduces semantic direct modeling (SDM), a novel approach that lifts direct modeling from low-level geometric modifications to high-level semantic interactions. This is achieved by utilizing a LLM fine-tuned with CAD-specific prompts, which can guide the LLM to reason through design intent and accurately interpret CAD commands, thereby allowing designers to express their intent using natural language. Additionally, SDM maps design intent to the corresponding geometric features in the CAD model through a new conditional, context-sensitive feature recognition method, which uses generative AI to dynamically assign feature labels based on design intent. Together, they enable a seamless flow from high-level design intent to low-level geometric modifications, bypassing tedious software interactions. The effectiveness of SDM has been validated through real mechanical design cases.