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VideoCAD: A Dataset and Model for Learning Long‑Horizon 3D CAD UI Interactions from Video
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Introduces VideoCAD, a 41K-video synthetic dataset of Onshape CAD UI interactions generated by a rule-based bot from DeepCAD models, plus the VideoCADFormer autoregressive transformer for behavior cloning and a VQA benchmark probing LLM 3D reasoning.
Problem
Existing UI-agent datasets focus on short, low-complexity web/mobile tasks and lack long-horizon, precision 3D CAD interactions captured as video with action annotations.
Approach
Automatically replay human-authored DeepCAD sketch-extrude sequences in Onshape through a hybrid Selenium/PyAutoGUI bot to produce large-scale, temporally aligned video-action pairs, and train a causal transformer decoder over ViT-encoded target and UI frames to predict low-level UI commands.
Key results
- VideoCADFormer reaches 98.08% command accuracy and 82.35% parameter accuracy, versus 96.25% and 78.72% for VPT, with mean perfectly predicted action rate of 87.54% vs 83.81%.
- On geometric fidelity, VideoCADFormer achieves 41.0% mean Chamfer success rate vs 28.5% for VPT, and 26.0% invalid rate vs 39.5%.
- On the VideoCAD VQA benchmark, LLMs underperform; e.g., GPT-4.1 reaches 47% on extrusion counting and 18% on depth-related questions, and all tested LLM UI agents fail to complete a CAD construction.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| use VideoCADFormer instead of VPT | VideoCAD action prediction · VideoCAD test | command accuracy (%): 96.25 -> 98.08 | Helped |
| use VideoCADFormer instead of VPT | VideoCAD action prediction · VideoCAD test | parameter accuracy (%): 78.72 -> 82.35 | Helped |
| use VideoCADFormer instead of VPT | VideoCAD action prediction · VideoCAD test | mean perfectly predicted actions (%): 83.81 -> 87.54 | Helped |
| use VideoCADFormer instead of VPT | CAD generation · VideoCAD geometric fidelity, mean across sequence lengths | Chamfer success rate (%): 28.5 -> 41.0 | Helped |
| use VideoCADFormer instead of VPT | CAD generation · VideoCAD geometric fidelity, mean across sequence lengths | mean Chamfer distance: 0.0473 -> 0.0374 | Helped |
| use VideoCADFormer instead of VPT | CAD generation · VideoCAD geometric fidelity, mean across sequence lengths | invalid sample rate (%): 39.5 -> 26.0 | Helped |
| add past action inputs (ablation) | VideoCADFormer · VideoCAD ablation test | mean perfectly predicted actions (%): 73.11 -> 79.27 | Helped |
| add past UI state inputs (ablation) | VideoCADFormer · VideoCAD ablation test | mean perfectly predicted actions (%): 77.86 -> 79.27 | Helped |
| add past action and UI state inputs (ablation) | VideoCADFormer · VideoCAD ablation test | mean perfectly predicted actions (%): 5.59 -> 79.27 | Helped |
| add timestep embeddings (ablation) | VideoCADFormer · VideoCAD ablation test | mean perfectly predicted actions (%): 79.39 -> 79.27 | No clear effect |
| add color jitter (ablation) | VideoCADFormer · VideoCAD ablation test | mean perfectly predicted actions (%): 79.27 -> 79.24 | Hurt |
| use sketches instead of kernel-generated target images (ablation) | VideoCADFormer · VideoCAD ablation test | mean perfectly predicted actions (%): 79.27 -> 79.31 | No clear effect |
Surprising findings
- Frontier LLMs such as GPT-4.1, Claude-3.7 and Gemini-2.5 fail to complete any full CAD construction as UI agents.
- Sketch-style inputs slightly outperform kernel-rendered images, while realistic (ControlNet) images perform worst.
Limitations
- All trajectories are synthetic from a rule-based bot, lacking natural variability in timing, errors, and strategy.
- Covers only sketch-extrude operations on Onshape, omitting fillets, sweeps, lofts and assemblies.
- End-to-end geometric evaluation is run only on a small subset (200 sequences) due to rendering cost.
Experimental setup
Datasets: DeepCAD
Benchmarks: VideoCAD test split VideoCAD VQA
Metrics: command accuracy parameter accuracy perfectly predicted actions Chamfer distance Chamfer success rate invalid rate VQA accuracy
Baselines: VPT Pix2Act Pearce et al. Random Human Expert
Builds on: Video Pre-training (VPT) Pix2Act DeepCAD
Closest papers by meaning
- cadrille: Multi-modal CAD Reconstruction with Reinforcement Learning (ICLR 2026 · similarity 0.87)
- GeoCAD: Local Geometry-Controllable CAD Generation with Large Language Models (NeurIPS 2025 · similarity 0.86)
- CAD-GPT: Synthesising CAD Construction Sequence with Spatial Reasoning-Enhanced Multimodal LLMs (AAAI 2025 · similarity 0.85)
- FlexCAD: Unified and Versatile Controllable CAD Generation with Fine-tuned Large Language Models (ICLR 2025 · similarity 0.85)
- Text2CAD: Generating Sequential CAD Designs from Beginner-to-Expert Level Text Prompts (NeurIPS 2024 · similarity 0.85)
- CAD-Editor: A Locate-then-Infill Framework with Automated Training Data Synthesis for Text-Based CAD Editing (ICML 2025 · similarity 0.85)
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