VLofSGnotreferenced

by Tim C. Lueth, SG-Lib Toolbox: SolidGeometry 5.6 - Surfaces
Introduced first in SolidGeometry 5.0, Creation date: 2020-10-03, Last change: 2025-09-14

returns the logical index of vertices that are not referenced in a triangualtion

Description

This function is important to adjust surfaces created by delaunay or alphashape

See Also: SGofVLdelaunay , SGofVLalphaShape

Example Illustration

missing image of VLofSGnotreferenced(SG)

Syntax

vi=VLofSGnotreferenced([SG])

Input Parameter

SG: Solid Geometry

Output Parameter

vi: logical index of not referenced vertices

Examples


loadweb JACO_robot.mat
SGsurfaces(JC6); SGC=ans;
SGofVLdelaunay(SGC{3}.VL); SG=ans
VLofSGnotreferenced(SG)

Copyright 2020-2025 Tim C. Lueth. All rights reserved. The code is the property of Tim C. Lueth and may not be redistributed or modified without explicit written permission. This software may be used free of charge for academic research and teaching purposes only. Commercial use, redistribution, modification, or reverse engineering is strictly prohibited. Access to source code is restricted and granted only under specific agreements. For licensing inquiries or commercial use, please contact: Tim C. Lueth

Algorithm (Workflow)

This function identifies vertices in a solid geometry (SG) that are not referenced in a triangulation. It is useful for adjusting surfaces created by Delaunay or alpha shapes.

Input Parameters

SG: Solid Geometry, which can be a Delaunay triangulation, a general triangulation, or a structure containing vertex list (VL) and face list (FL).

Output Results

vi: Logical index of vertices that are not referenced in the triangulation.

Algorithm Steps

Retrieve the solid geometry (SG) from the input parameters using getfuncparams.
Check if SG is a Delaunay or general triangulation:
- If true, extract points and connectivity list from the triangulation.
- If the connectivity list has 4 columns, it indicates a tetrahedral mesh, and the free boundary is computed to get the surface.
- If not, the surface already exists, and the connectivity list is used directly.
Convert SG to a standard format using SGofSG.
Identify unique vertices in the face list (FL) using unique.
Determine which vertices are not referenced by converting the unique vertex indices to a logical array using find2logical.
If no output is requested, plot the geometry:
- Use SGfigure to set up the figure.
- Plot the alpha shape of SG with SGplotalpha.
- Highlight the non-referenced vertices using VLplot.

Algorithm explaination created using ChatGPT on 2025-08-19 07:15. (Please note: No guarantee for the correctness of this explanation)

Last html export of this page out of FM database by TL: 2025-09-21