3D Mesh Hole Filling with Recursive Boundary Splitting

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Solution Overview

Problem

Existing methods for filling mesh holes in 3D digital models often produce suboptimal geometries or require complex postprocessing, especially for mesh holes with complex or degenerated boundaries, and may not terminate reliably.

Innovation Solution

A method that uses a divide-and-conquer approach to split the boundary curve of a mesh hole at suitable locations, recursively dividing it into smaller curves using a maximized triple of boundary vertices connected by a tangential connecting curve, ensuring the new curves are smaller than the original, and adding Steiner vertices as needed to ensure termination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the advancing front approach is used to fill mesh holes, then the hole filling can be achieved, but the method may produce suboptimal geometries and require postprocessing steps

Engineering Contradiction:
Improvemesh hole filling qualityVSAvoidpostprocessing requirements
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The boundary curve is divided into multiple segments by identifying split points where the curve intersects with the mesh surface. Each segment is then processed independently to create triangular patches, allowing for more precise control over the geometry of each portion of the filled hole while maintaining overall coherence

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The boundary curve is preprocessed by finding intersection points with the mesh surface and dividing it into segments before the actual hole filling process. This preliminary segmentation ensures that subsequent triangulation operations work with manageable, well-defined portions of the boundary, eliminating the need for postprocessing corrections

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If Laplace equation is used for surface interpolation, then the mathematically correct surface is obtained, but the filled mesh hole tends to be not very natural when the natural surface has mean curvature different from zero

Engineering Contradiction:
Improvesurface interpolation accuracyVSAvoidnatural appearance of filled surface
Core Design Contradiction:
Manufacturing precisionVSShape

Solution Approach 1:

Instead of applying a global Laplace interpolation that enforces zero mean curvature everywhere, the method creates local triangular patches that follow the boundary curve segments. Each patch is constructed to match the local geometry and curvature characteristics of the surrounding mesh, preserving natural surface variations while maintaining mathematical correctness

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If the advancing front approach is used for mesh hole filling, then hole filling can be performed, but it may be difficult to ensure termination for mesh holes with complex or degenerated boundaries

Engineering Contradiction:
Improvehole filling capabilityVSAvoidtermination guarantee
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The boundary curve is segmented at intersection points with the mesh surface, creating a finite number of well-defined segments. This segmentation transforms the continuous boundary problem into a discrete set of manageable segments, ensuring that the algorithm progresses through a finite sequence of operations and must terminate

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The boundary curve is preprocessed to identify all intersection points and establish a segmentation before the filling process begins. This preliminary analysis ensures that even complex or degenerated boundaries are properly divided into valid segments, guaranteeing that the algorithm can handle any boundary configuration and will terminate

Inventive Principle:
Principle #10Preliminary action

4Device complexity

If 3D hole filling problems are turned into 2D problems, then the complexity is reduced, but insufficient results are obtained for mesh holes with complex boundaries

Engineering Contradiction:
Improveproblem solving complexityVSAvoidhole filling result quality
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The method works directly in 3D space by finding where the boundary curve intersects with the mesh surface and creating 3D triangular patches. This maintains the full spatial information and geometric relationships without reducing to 2D, ensuring accurate results for complex boundaries while managing complexity through systematic 3D triangulation

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS12591717B2Filling a mesh hole
Publication Date: 2026.03.31 EXOCAD
  • US12591717B2 patent drawing
  • US12591717B2 patent drawing
  • US12591717B2 patent drawing

AI summary

The invention relates to a method for filling a mesh hole in a mesh of a 3D digital model. A boundary of the mesh hole is provided by a first closed boundary curve comprising boundary edges connecting boundary vertices of a first plurality of boundary vertices. The method comprises selecting a maximized triple of boundary vertices comprising a first, a second and a third boundary vertex. The selected maximized triple is maximized by selecting a boundary vertex of the first plurality of boundary vertices as the third boundary vertex of the selected maximized triple. The selected maximized triple satisfies a first criterion. The first and the second vertex of the selected maximized triple are connected using a connecting curve from the first to the second boundary vertex.