Study notes for Ian Stroud, Boundary Representation Modelling Techniques (Springer, 2006).

This chapter is a survey of “what a modeller must do in the real world”: verification, healing, format conversion, and downstream computations.

1) Model verification

Verification is the discipline of proving your model is internally consistent:

  • topological checks (closure, orientation, manifoldness where required)
  • geometric checks (curve/surface consistency, trims within tolerance)
  • intersection checks (self-intersections, invalid overlaps)

The book contrasts how different systems approach verification, highlighting that it’s not just a function—it’s a workflow and a toolchain.

2) Model healing

Healing is the practical complement to verification:

  • assembly healing (aligning and fixing component relationships)
  • topological healing (fixing broken adjacency, missing loops, inconsistent use entities)
  • geometric healing (rebuilding curves/surfaces, smoothing, retolerancing)
  • combined healing strategies (because geometry and topology errors interact)

Healing policy is part of your product identity: aggressive healing can surprise users; conservative healing can leave unusable models.

3) Recreating a B-Rep from an STL file

This is a classic hard problem:

  • STL gives triangles, not analytic faces.
  • You must segment the mesh, fit surfaces, and rebuild topology.
  • The result is rarely perfect; you need tolerances, snapping, and verification.

4) Rapid prototyping, reverse engineering, and computation

The chapter also discusses:

  • using models for prototyping workflows
  • reverse engineering pipelines
  • computing volume
  • tetrahedral decomposition (bridge to FEM/CAE)
  • patterns (repeated features/instances)

Chapter outline (from the book)

Major sections

  • 14.1 Model Verification
  • 14.4 Recreating A B-Rep From An Stl File

Selected subsections

  • 14.1.1 Justification
  • 14.1.2 Verifications
  • 14.1.3 Model verification in ACIS

Implementation checklist

  • Treat verification/healing as a first-class module, not a debug-only add-on.
  • Provide “diagnostics output”:
    • what failed, where, and with what tolerance
  • Build conversion tools:
    • B-Rep ↔ mesh pipelines with controlled deviation
  • For volume and tetrahedralization:
    • ensure solids are watertight
    • provide fallback strategies when not watertight

Verification + healing: make it user-facing

Industrial CAD exposes healing tools because imports are messy:

  • show diagnostics
  • allow controlled healing steps
  • keep audit logs of changes

Practical exercises

  • Implement a topology validation report:
    • list invalid faces/loops
    • count self-intersections
    • output a “repair suggestion” list (even if manual)