Lattice structures exhibit unique properties including large surface area, and a highly distributed loadpath. This makes them very effective in engineering applications where weight reduction, thermal dissipation and energy absorption are critical. Further, with the advent of additive manufacturing (AM), lattice structures are now easier to fabricate. However, due to inherent surface complexity, their geometric construction can pose significant challenges.

A classic strategy for generating lattice structures exploits analytic surface-surface intersection; this however lacks robustness and scalability. An alternate strategy is voxel mesh based isosurface extraction. While this is robust and scalable, the surface quality is mesh-dependent, and the triangulation will require significant post-decimation. A third strategy relies on explicit geometric stitching where tessellated open cylinders are stitched together through a series of geometric operations. This was demonstrated to be efficient and scalable, requiring no post-processing. However, it was limited to lattice structures with uniform beam radii. Further, existing algorithms rely on explicit convex-hull construction which is known to be numerically unstable.

In this paper, a combinatorial stitching strategy is proposed where tessellated open cylinders of arbitrary radii are stitched together using topological operations. The convex hull construction is handled through a simple and robust projection method, avoiding expensive exact-arithmetic calculations, and improving the computational efficiency. This is demonstrated through several examples involving millions of triangles. On a typical 8-core desktop, the proposed algorithm can generate approximately 4 million triangles per second.

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