image-based meshing

Meshing from 3D imaging data presents a number of challenges but also unique opportunities for presenting a more realistic and accurate geometrical description of the computational domain. There are generally two ways of meshing from 3D imaging data:

The majority of approaches used to date still follow the traditional CAD route by using an intermediary step of surface reconstruction which is then followed by a traditional CAD-based meshing algorithm.Viceconti et al, 1998. TRI2SOLID: an application of reverse engineering methods to the creation of CAD models of bone segments. Computer Methods and Programs in Biomedicine, 56, 211–220. CAD-based approaches use the scan data to define the surface of the domain and then create elements within this defined boundary. Although reasonably robust algorithms are now available, these techniques are often time consuming, and virtually intractable for the complex topologies typical of image data. They also do not easily allow for more than one domain to be meshed, as multiple surfaces are often non-conforming with gaps or overlaps at interfaces where one or more structures meet.Young et al, 2008. An efficient approach to converting 3D image data into highly accurate computational models. Philosophical Transactions of the Royal Society A, 366, 3155–3173.

This approach is the more direct way as it combines the geometric detection and mesh creation stages in one process which offers a more robust and accurate result than meshing from surface data. Voxel conversion technique providing meshes with brick elements Fyhrie et al, 1993. The probability distribution of trabecular level strains for vertebral cancellous bone. Transactions of the 39th Annual Meeting of the Orthopaedic Research Society, San Francisco. and with tetrahedral elements Frey et al, 1994. Fully automatic mesh generation for 3-D domains based upon voxel sets. International Journal of Methods in Engineering, 37, 2735–2753. have been proposed.

Another approach generates 3D tetrahedral or tetrahedral elements throughout the volume of the domain, thus creating the mesh directly with conforming multipart surfaces. Young et al, 2008. An efficient approach to converting 3D image data into highly accurate computational models. Philosophical Transactions of the Royal Society A, 366, 3155–3173.

The steps involved in the generation of models based on 3D imaging data are:

An extensive range of image processing tools can be used to generate highly accurate models based on data from 3D imaging modalities, e.g. MRI, CT, MicroCT (XMT), and Ultrasound. Features of particular interest include:

• Segmentation tools (e.g. thresholding, floodfill, level set methods, etc.)
• Filters and smoothing tools (e.g. volume- and topology-preserving smoothing and noise reduction/artefact removing).

The image-based meshing technique allows the straightforward generation of meshes out of segmented 3D data. Features of particular interest include:

• Multi-part meshing (mesh any number of structures simultaneously)
• Mapping functions to apply material properties based on signal strength (e.g. Young's modulus to Hounsfield scale)
• Smoothing of meshes (e.g. topological preservation of data to ensure preservation of connectivity, and volume neutral smoothing to prevent shrinkage of convex hulls)
• Export to FEA and CFD codes for analysis (e.g. node sets, shell elements, material properties, contact surfaces, boundary layers, inlets/outlets)

• Biomechanics and design of medical and dental implants
• Food science
• Forensic science
• Materials science (composites and foams)
• Nondestructive testing (NDT)
• Paleontology and functional morphology
• Reverse engineering
• Soil science
• Petrophysics

• Image segmentation

• [https://www.computing-objects.com/ Computing-Objects] commercial C++ libraries for mesh generation & FEM computation
• ScanIP commercial image-based meshing software: [http://www.simpleware.com www.simpleware.com]
• Mimics 3D image-based engineering software for FEA and CFD on anatomical data: [http://www.materialise.com/mimics Mimics website] {{Webarchive|url=https://web.archive.org/web/20110212150457/http://www.materialise.com/mimics |date=2011-02-12 }}
• Google group on image-based modelling: [http://groups.google.co.uk/group/image-based-modelling]
• Avizo Software's 3D image-based meshing tools for CFD and FEA
• iso2mesh: a free 3D surface and volumetric mesh generator for matlab/octave [http://iso2mesh.sourceforge.net/]
• [http://www.ctcms.nist.gov/oof/ OOF3D], object oriented finite element analysis from the NIST
• [https://www.volumegraphics.com/en/products/vgstudio-max/add-on-modules-for-simulation.html VGSTUDIO MAX], Commercial CT analysis software for industry. They offer an add-on module for FEM meshing.

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Category:Mesh generation

Category:Computer graphics algorithms

Category:3D computer graphics