Geometric Kernel

Geometric Kernel is the foundational logical capability of computing solid and surface boundary-representation (B-rep) operations — Booleans, blends, offsets, intersections, surface trimming, tessellation — that underpin every modern 3D CAD product. It is the layer below the user interface, and the choice of kernel materially affects feature robustness, multi-CAD interoperability, and downstream JT/STEP fidelity.

The major kernels

• Parasolid (Siemens) — used by NX, Solid Edge, SolidWorks, Onshape, and many third-party tools; B-rep and tessellation, exposed via the XT format.
• ACIS (Spatial / Dassault) — used historically by AutoCAD, BricsCAD, and CADKEY; SAT/SAB formats.
• CGM (Convergence Geometric Modeler) (Dassault) — the kernel underneath CATIA V5/V6 and 3DEXPERIENCE.
• Open CASCADE Technology (OCCT) — the dominant open-source kernel; underpins FreeCAD and Salome.
• Granite (PTC) — the kernel inside Creo and Pro/ENGINEER.

Why it matters

Two CAD products sharing a kernel (e.g., NX and Solid Edge on Parasolid) have inherently higher round-trip fidelity than products on different kernels. Multi-CAD environments care about kernel pairing because boundary-representation tolerances and curve evaluators differ.

Relationships (see sidebar)

• Part of CAD 3D Design — the engine underneath the modeling experience.
• Supports CAD Design and Detailed Design.
• Implemented by the major CAD products: NX, CATIA, SolidWorks, Creo, Solid Edge, and Onshape.