We present ReCAD, a reinforcement learning (RL) framework that bootstraps pretrained large models (PLMs) to generate precise parametric computer-aided design (CAD) models from multimodal inputs by leveraging their inherent generative capabilities. With just access to simple functional interfaces (e.g., point coordinates), our approach enables the emergence of complex CAD operations (e.g., pattern replication and mirror). This stands in contrast to previous methods, which typically rely on knowledge injected through supervised fine-tuning (SFT), offer limited support for editability, and fail to exploit the strong generative priors of PLMs. Specifically, the ReCAD framework begins by fine-tuning vision-language models (VLMs) to equip them with basic CAD model generation capabilities, where we rewrite CAD scripts into parameterized code that is leveraged to generate accurate textual descriptions for supervision. Then, we propose a novel RL strategy that incorporates parameterized code as guidance to enhance the model’s reasoning on challenging questions. Furthermore, we employ a hierarchical primitive learning process to progressively teach structured and compositional skills under a unified reward function that ensures both geometric accuracy and semantic fidelity. ReCAD sets a new state-of-the-art in both text-to-CAD and image-to-CAD tasks, significantly improving geometric accuracy across in-distribution and out-of-distribution settings. In the image-to-CAD task, for instance, it reduces the mean Chamfer Distance from 73.47 to 29.61 (in-distribution) and from 272.06 to 80.23 (out-of-distribution), outperforming existing baselines by a substantial margin.

Elastic rods are commonly seen in our daily life. Although humans are sensitive to the shape change of rods, it is not intuitive to estimate the external forces applied to generate the deformation. We propose a method to interactively track the elastic linear objects by using the Cosserat rod model to regulate the captured noisy points. We develop a framework based on particle filters to work with the physics-based model, turning the inverse physics problem into a forward simulation and search problem. We show that with the proposed method, we can simultaneously digitalize the shape as well as the external forces on real-world elastic rods. With these capabilities, we demonstrate virtual and augmented reality applications to facilitate the interaction with elastic linear objects. The tracking performance is also validated with experiments.