Express Mesh Component


The Open Cascade Express Mesh SDK features an advanced algorithm for fast meshing of surfaces represented with BRep shapes. It provides triangular and quadrangular meshing of a shape containing Faces (a Solid, a Shell, or a compound of Faces). Each face is tessellated individually, nevertheless providing connectivity between triangles built on connected faces (on faces that share edges). The Express Mesh algorithm takes several input parameters, such as element size, chordal deflection and angular deviation, so the user has an extended level of control over the mesh quality and the number of generated mesh elements.


Parameters The Express Mesh algorithm has the following input parameters:
  1. Mesh element type. This parameter selects the kind of mesh elements produced – triangular or quadrangular.
  2. Minimal element size. This parameter defines the lower size limit of an element side. Increasing this parameter the user will speed up the meshing process at the expense of quality (surface feature details).
  3. Maximal element size. This parameter defines the upper size limit of an element side.
  4. Deflection. This parameter defines the maximal allowable chordal deviation of a mesh element from the original surface.
  5. Angular deviation. This parameter defines the maximal angular deviation of mesh elements’ normal vectors from the surface normal vectors. The less this parameter is, the greater is the number of mesh elements on a curved area of a surface.
To simplify the choice of parameters for meshing a particular shape, a special class is available to measure the shape and suggest some optimal parameters to mesh that particular shape. Discretization and Healing To increase the robustness, the Express Mesh SDK features some useful healing operations:
  • Special treatment allows to achieve well-spaced discrete segments along edges of the input shape, even if an edge’s curve is badly parameterized;
  • Detection and resolving self-intersections on discrete curves: capability of removing small loops;
  • Connecting adjacent discrete curves of a wire to achieve a contiguous closed contour;
  • Detection and resolving mutual intersections between wires on a face.


The Express Mesh algorithm provides higher performance and better control over mesh quality compared to open source BRepMesh algorithm from OCCT. It can therefore be used for applications where the speed of surface meshing is crucial. Thanks to controlled element size and quality, the final generated mesh can be also used in some FEA applications. Due to the high speed of mesh computation it can also be used as an alternative algorithm for visualization purposes. This component was successfully used in a number of projects including SIMOPTIC software (by DBM Reflex).


The Express Mesh SDK is based on the latest version of Open CASCADE Technology, and requires no other external software. It is available on all platforms supported by the corresponding version of Open CASCADE Technology. Operational mode and possible limitations are described in the documentation accompanying the module.
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