Creating Surface Meshes from Implicit Bodies


Implicit bodies often need to be surface-meshed for the purposes of simulation, exporting to other formats, and manufacturing. Since implicits are defined by continuous fields, a few steps need to be taken to properly discretize them and generate a clean mesh. Note that in nTop we refer to surface meshes as simply ‘meshes’, while volume meshes are specified as volume or solid meshes. Information on volume meshing can be found here.

Mesh from Implicit body

Whenever meshing an implicit body, the first step must be to use the Mesh from Implicit Body block. The feature size input of this block should be less than the minimum feature size you want to capture in your implicit body. Because all future meshes will be based on this, you should consider using a very small feature size for intricate implicit bodies, and then remesh to a coarser mesh later. The adaptivity input takes in a number greater than 0, which controls if mesh elements will increase in size over flat areas. Low values will result in a more uniform and accurate mesh, while larger values will result in lower element counts. 


Remesh Surface

The Remesh Surface block provides more control over how the mesh is constructed. It is used to clean up defects in a mesh, consolidate meshes into fewer elements, and/or spatially vary the mesh density.

The edge length input in the Remesh Surface block specifies the approximate edge length of the mesh elements. The input can be a singular, consistent value, or a scalar field, meaning you can spatially vary the size of the mesh.


The Span angle input is used in the refinement of elements that lie on curves. It signifies the maximum allowed angle that elements on curved surfaces are allowed to span. If we set the span angle to be smaller, we can see that the elements lying on the curve will be refined more to fit the smaller span angle:


The Growth rate specifies the ratio of element size from one element to another. The number can be anything greater than 1. The smaller the number, the more uniform the mesh. You can see below how changing the growth rate from 2 to 1.05 creates a more uniform mesh.


The Feature angle input controls the degree to which curved surfaces are converted to flat edges in a mesh. The value represents the maximum allowed angle between two adjacent planes that define an edge. A lower value will result in more planar regions of the mesh where an input surface is curved.


A minimum feature size can be specified to ensure that small features won’t be obscured in the resulting mesh. The edge length will be targeted throughout the body, but where features approach the min. feature size, the mesh will be refined. If left blank, the default feature size is 0.05% of the input edge length.




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