Cleaning Open Meshes in PiXYZ Studio

1. Cleaning Open Meshes in PiXYZ Studio

This tutorial has been verified using Unity 2019 LTS and PiXYZ 2020.1.1.8.

An improperly constructed surface can lead to issues with tessellation, lighting, and rendering, as well as any additional processing to the mesh, such as conversion to STL for 3D printing. PiXYZ Studio offers tools to automatically clean open, patch-based as well as polygonal meshes. (Figures 01-04)

Figure 01: This hood is noncontinuous, made of many close, but disconnected, surfaces.

Figure 02: Thanks to the Repair CAD operation, this hood is one continuous surface.

Figure 03: Each of the subsurfaces in a noncontinuous surface will tessellate with gaps between them.

Figure 04: A continuous surface will tessellate into a smooth polygonal mesh without cracks.

2. Repairing patch-based CAD meshes

1. Select the surface(s) you’d like to repair. Otherwise, the Repair CAD will operate on all patch-based surfaces in the Product Structure.

2. From the CAD dropdown, select Repair CAD. (Figure 05)

Figure 05: Repair CAD menu entry

3. The Repair CAD dialog (Figure 06) offers two options:

The tolerance, 0.1mm by default, is the threshold for joining surfaces. Any surfaces closer than the tolerance will be joined.

PiXYZ Studio can optionally attempt to orient the newly created faces. The results will vary by mesh. When you’re not sure how a setting will affect an operation, it’s recommended to enable Modifier History and revise parameters as necessary.

Figure 06: Repair CAD dialog

4. Adjust settings as necessary and click Execute.

Repairing a polygonal mesh is similar, but offers an additional option.

1. Select the polygonal meshes you wish to repair, otherwise the repair operation will act on every polygonal mesh in the scene.

2. Select Repair Mesh from the Mesh dropdown. (Figure 07)

Figure 07: Repair Mesh works similarly to Repair CAD.

3. The Repair Mesh dialog has the same options as Repair CAD, with the additional option to crack non-manifold edges resulting from the repair. (Figure 08)

Figure 08: Repair Mesh dialog

4. Adjust settings accordingly and click Execute.

3. A Point of Caution

There is one potential issue with repair operations. This applies to both patch-based and polygonal meshes. Because the operations merge points closer than the given tolerance, fine detail will be lost (Figures 09-10). The solution is to handle surfaces with fine detail separately, both in repair and tessellation.

Figure 09: Text on a CPU, before the Repair Mesh operation.

Figure 10: Because the vertices are so close, the Repair Mesh operation merges some. In this case, entire characters were lost.

4. Conclusion

Open meshes wreak havoc in many areas, from lighting and rendering to physical export to 3D printing. Proper construction is ideal, but PiXYZ Studio can repair CAD-based and polygonal meshes.