New Method for Removing Self-Intersecting 3D Mesh Data

In the recently published ‘A Robust Algorithm to Remove the Self-intersection of 3D Mesh Data without Changing the Original Shape,’ authors Jiang Zhu, Yurio Hosaka, and Hayato Yoshioka tackle the issue of self-intersection in digital manufacturing, developing an algorithm to eliminate self-intersection of 3D mesh models.

Mesh models, generated in 3D, are popular today for use in manufacturing today, allowing users to attain digital data efficiently at a large-scale during scanning. 3D prints can then be built according to the digital data, with the 3D triangle mesh model being the most common. The authors emphasize the importance of quality in mesh data, optimally comprised of a closed triangle ‘without topological errors’ and intersecting triangles. Numerous types of non-manifold parts of meshes are created inadvertently during 3D modeling or scanning including:

• Holes
• Areas with zero thickness
• Self-intersections

 “Since such non-manifold meshes do not exist in physical world, they must be fixed in advance for actual usage,” state the researchers. “In conventional reverse engineering process, the non-manifold meshes are fixed by the operator manually.

“The increasing of the mesh complexity makes such process a very time-consuming task. In order to realize the automation of 3D sensing and 3D printing, automatic detection and correction of the non-manifold mesh became an essential task to solve.”

The developed algorithm must do the following:

• Detect intersected facets
• Divide the intersected facets
• Find the outside facets
• Delete the inner facets and burying facets

For this study, the researchers created a pyramid-in-cube model, showing that all the intersected triangles were separated into smaller triangles along the crossing lines. The model shows the successful removal of intersections using the research team’s method.

Overview of the proposed method

The research team used a second model, use to test intersected balls. The model was made up of ten balls, and each one designed with 300 triangle facets.

Processed result of Pyramid-in-Cube model

The last model, created as a replica of a Nobel model, was reproduced from a scan comprised of 2,656 vertices and 5,067 triangle facets. Although there were 33 intersected triangles, with all of them being very small, all self-intersected parts were replaced by the divided facet—with the model created on a Prodigy Plus 3D printer and no errors.

Processed result of intersected balls model

“The experimental result indicates that comparing with the commercial software, this proposed method is more effective to remove the self-intersected parts in the 3D model, while keep the original shape unchanged. It could be used to fix the non-manifold mesh problems in 3D printing or FEM analysis. In addition, this method can also be modified for Boolean operation of 3D mesh models.”

The topic of mesh in 3D printing is broad, as scientists experiment with different materials, innovate for medical research, cancer treatment, and more. What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.