How to filter mesh


Learn how to select/filter mesh from a larger mesh body (surface or solid). One of the applications of this filtering is to select the regions required for a brace design for implants.

Applies to:

  • Orthopedic Implants
  • Meshing


1. First, we start with mesh using the Import Mesh block (What file types can nTop import and export?) as our base. We will then convert the imported mesh into an implicit body using the Implicit Body from Mesh block.

2. Define the intersection geometry you wish to use to filter the mesh. In this example, we will be using two techniques:

a) Combination of Implicit Bodies

The example GIF below shows a Boolean Union of a Sphere, Cylinder, and Box for defining the intersection geometry.


b) Imported CAD Geometry

We can also use a combination of imported CAD (How to work with CAD bodies) and Scale Object blocks to define the intersection geometry. In this case, we can use a CAD Face selection.

3. We have reached the important step of the process and have our Mesh and Intersection geometry ready. We start with a Boolean Subtract of the Intersection Geometry from the Mesh.

4. Similar to the second step, we could use two methods to filter the mesh. We will mesh the implicit body before filtering using the Mesh from Implcit Body (How to mesh complex parts) block.

Note: The mesh must have sharp edges to get a clean edge result. You can enable the Sharpen option or switch to the Shapen extents overload to get a good result.

a) Filter Mesh by Floodfill

    • Insert the Mesh generated in the above step into the Mesh input
    • Select the Origin input and move it near the surface you want to extract.
    • Set the Angle for selection.
    • An optional Direction input, if not provided, the origin point will be projected to the nearest face.

b) Remove Mesh Faces by Body

You can use the imported mesh directly for this method, as it is a surface mesh with the Subtraction Body. When we check the Reverse option, it filters the faces outside the Implicit Body instead of inside.

And that’s it! You’ve successfully selected mesh faces from a mesh

Do you still need help? Contact the support team, and we’ll be happy to help!

Download the Example file:

More on this topic:


 cad select face mesh surface lattice conformal selection fill filter join quad how-to extract flood 
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