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Technical Architecture — Index

Last synthesized: April 2026

This section documents the technical foundations of RapidDraft's CAD integration, geometry reasoning, error detection, and manufacturing intelligence systems.

Documents

Document Purpose Audience
Drawing_Error_Detection.md Taxonomy of drawing and CAD errors RapidDraft detects; five-pack check system; detection mechanism CAD engineers, QA leads, product managers
NX_Graphy_Knowledge_Graph.md Knowledge graph representation of CAD parts; extraction via NXOpen; application to parametric dimensioning ML engineers, CAD integration engineers, geometry specialists
Vision_Model_Integration.md Role of vision models in drawing validation; what they do well vs. limitations; confidence handling Product managers, QA, vision/ML team
CAD_Viewer_and_Annotation_Architecture.md Viewer stack choices, B-Rep vs mesh trade-offs, and the annotation-layer architecture for 3D and drawing review Frontend engineers, CAD platform engineers, product leads
OCCT_FreeCAD_Runtime_Architecture_Audit.md Code-backed audit of the current mixed FreeCAD + OCCT runtime: preview rendering, canonical scene, Part Facts, DFM, collaboration, and FreeCAD retirement risk Backend engineers, CAD platform engineers, product leads
No_FreeCAD_Architecture_Notes.md Target-state notes for a no-FreeCAD branch: what stays in the web shell, what must be rebuilt in OCCT, and what the migration risks are Backend engineers, CAD platform engineers, product leads
Runtime_Architecture_Direction.md Current direction for splitting display, review, analysis, and artifact generation into clear runtime boundaries Backend engineers, CAD platform engineers, product leads
NX Live Control Architecture Explains how RapidDraft controls the real NX session for review drawings and why that layer sits beside the neutral geometry stack CAD platform engineers, product leads, automation engineers
Drawing_Analysis/_INDEX.md Overview of the Label Studio training track that supports RapidDraft drawing review ML engineers, annotators, product leads
Drawing_Analysis/Label_Studio_Schema.md Operational object classes, error labels, metadata, and pipeline rules for v1 labeling ML engineers, annotators
Drawing_Analysis/Visual_Label_Reference.md Inline visual examples that keep annotation regions consistent across collaborators Annotators, reviewers
Code_Review/_INDEX.md April 2026 code review — prioritized findings for rapiddraft_utumpitch, formatted for consumption by Codex Engineering leads, backend/frontend maintainers
Code_Review/09_Runtime_Pipeline_Audit_Synthesis.md Readable synthesis of the older runtime-pipeline audit and no-FreeCAD architecture discussion Engineering leads, backend/frontend maintainers

Core Concepts

Knowledge Representation

RapidDraft extracts CAD models into a typed knowledge graph: Part → Features → Bodies → Faces → Expressions. This schema enables algorithmic reasoning about design intent, manufacturing constraints, and automatic dimensioning.

Error Detection (Packs A–E)

  • Pack A: Drawing spec and compliance (format, standards, metadata)
  • Pack B: Dimensional completeness (all features dimensioned, tolerances specified)
  • Pack C: Tolerance and GD&T logic (datum priority, symbol validity, stack-up)
  • Pack D: Manufacturing feasibility (DFM, tool access, thin walls, surface finish)
  • Pack E: Assembly and interface logic (mating, clearance, fastener specs)

Vision Model Scope

Vision models extract drawing callouts and flag specification–geometry mismatches. Not used for 3D manufacturability checks (use CAD geometry for that). Emphasis on explainability and engineer-in-the-loop validation.

Integration Points

  • NX Integration: NXOpen API for topology extraction, feature iteration, expression management, and in-session live control for review drawing workflows
  • Neutral Format Pipeline: STEP/IGES fallback when native CAD access unavailable
  • NX Live Control: in-session host used when the workflow must stay inside the real NX drafting session rather than a detached helper or a neutral-file export path
  • Drawing Memory: Captured check outcomes re-applied across CAD revisions
  • AI Dimensioning: KG informs where vision and heuristics suggest dimensions
  • Manufacturing Check Engine: Deterministic rules on CAD B-Rep (Packs B–E); vision for drawing validation (Pack A)

Technical Dependencies

  • NXOpen: Siemens NX geometry and feature APIs
  • STEP/IGES Parsers: Neutral CAD format processing
  • Vision Models: OCR and drawing specification extraction (local or cloud)
  • Graph Storage: JSON (lightweight) or Neo4j (enterprise scaling)
  • Rule Engine: Deterministic checks on geometry; ML-assisted confidence scoring

Roadmap Notes

  • Phase 1 (MVP): Single-body part reasoning; NX + STEP support; basic feature recognition
  • Phase 2: Multi-body assembly reasoning; Teamcenter integration; advanced GD&T logic
  • Phase 3: Cross-supplier assembly tolerance analysis; real-time collaboration graph updates

Sources