arXiv subjects

Amit Regmi

Publications and source records attributed to Amit Regmi.

2 recordsLinked to original sources

arXiv2026

Ortho2CAD: 3D CAD generation from orthographic drawings using vision language models

Engineering design intent is often communicated through rasterized orthographic drawings. However, downstream workflows require editable and parametrically defined 3D computer-aided design (CAD) models. To bridge this gap, we introduce vision language model (VLM) frameworks specifically designed to translate rasterized orthographic drawings into editable CadQuery code, which can then be converted into 3D CAD models. Firstly, due to unavailability of large scale orthographic drawing datasets, we create a pythonOCC-based drawing generator that renders first-angle orthographic projections from STEP models, with dashed hidden lines and bounding box dimensions, and generate over 1 million drawings from existing 3D CAD model datasets. We also create a dataset of 100 drawings with manually dimensioned features. We show that supervised fine-tuning applied on small open-source VLMs when paired CadQuery code is available improves reconstruction accuracy on corresponding test sets. For datasets without code labels, geometry-grounded reinforcement learning is performed which uses generated-solid intersection-over-union (IoU) with ground truth solid as the reward, improving code validity and cross-dataset generalization. Then, an inference time self-refinement framework for frontier VLMs is introduced which repeatedly repairs invalid codes and compares orthographic projections of generated 3D models with the input drawing to revise the CadQuery code. Our self-refinement framework with GPT 5.5 achieves 100% valid code generation and the highest mean IoU across all test sets, with an average relative improvement of more than 11% over the next-best method. We show that leveraging VLMs can effectively pave the way forward for orthographic drawing to 3D CAD reconstruction. Our implementation is available at https://github.com/AdityaJoglekar/Ortho2CAD.

cs.CE↗

arXiv2026

From Full and Partial Intraoral Scans to Crown Proposal: A Classification-Guided Restoration Assistance Pipeline

Single-unit crown restoration is among the most common procedures in clinical dentistry, with CAD/CAM workflows now designing crowns directly from intraoral scans. Partial scans are often preferred over full-arch scans for single-unit cases due to fewer stitching errors, yet most segmentation networks trained on full arches fail on partial scans, while end-to-end generative crown methods often produce over-smoothed surfaces that lose occlusal detail. We propose an end-to-end pipeline that takes a raw intraoral scan and target FDI tooth number as input and outputs an initial, patient-specific crown proposal for clinician refinement. The pipeline has three phases: (I) data preparation and pose standardization; (II) segmentation routed by scan type; and (III) crown proposal generation via context-aware retrieval and Blender-based fitting. We address partial-scan segmentation through a classify-then-align strategy: a DGCNN classifier categorizes the scan into one of five anatomical types, then coarse-to-fine RANSAC+ICP registration standardizes the jaw coordinate frame, followed by graph-cut optimization to refine tooth-gingival boundaries. Trained on 1,958 partial scans, the pipeline achieves macro-average DSC 0.9249, Recall 0.8919, and Precision 0.9615 across 17 semantic classes; a fine-tuned full-arch model reaches DSC 0.9347. The prepared tooth and its mesial and distal neighbors achieve DSC 0.9468-0.9569 with sub-millimeter Centroid Errors (0.2666-0.2774 mm). These centroids anchor a retrieval module using DGCNN embeddings and cosine similarity over neighboring and opposing teeth, followed by spline-guided alignment and Blender Python API refinement. The pipeline produces a preliminary crown shell in 2.5-3.5 minutes, offering a practical alternative to end-to-end generative approaches.

eess.IV↗