image-based meshing
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Image-based meshing is the automated process of creating computer models for
computational fluid dynamics Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows. Computers are used to perform the calculations required to simulate th ...
(CFD) and
finite element analysis The finite element method (FEM) is a popular method for numerically solving differential equations arising in engineering and mathematical modeling. Typical problem areas of interest include the traditional fields of structural analysis, heat ...
(FEA) from 3D image data (such as
magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...
(MRI), computed tomography (CT) or
microtomography X-ray microtomography, like tomography and X-ray computed tomography, uses X-rays to create cross-sections of a physical object that can be used to recreate a virtual model (3D model) without destroying the original object. The prefix ''micro-'' ...
). Although a wide range of mesh generation techniques are currently available, these were usually developed to generate models from
computer-aided design Computer-aided design (CAD) is the use of computers (or ) to aid in the creation, modification, analysis, or optimization of a design. This software is used to increase the productivity of the designer, improve the quality of design, improve c ...
(CAD), and therefore have difficulties meshing from 3D imaging data.


Mesh generation from 3D imaging data

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:


CAD-based approach

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. 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.


Image-based approach

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 and with tetrahedral elements 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.


Generating a model

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


Scan and image processing

An extensive range of
image processing An image is a visual representation of something. It can be two-dimensional, three-dimensional, or somehow otherwise feed into the visual system to convey information. An image can be an artifact, such as a photograph or other two-dimensiona ...
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).


Volume and surface mesh generation

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 Young's modulus E, the Young modulus, or the modulus of elasticity in tension or compression (i.e., negative tension), is a mechanical property that measures the tensile or compressive stiffness of a solid material when the force is applied leng ...
to
Hounsfield scale The Hounsfield scale , named after Sir Godfrey Hounsfield, is a quantitative scale for describing radiodensity. It is frequently used in CT scans, where its value is also termed CT number. Definition The Hounsfield unit (HU) scale is a linear tran ...
) * 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)


Typical use

*
Biomechanics Biomechanics is the study of the structure, function and motion of the mechanical aspects of biological systems, at any level from whole organisms to organs, cells and cell organelles, using the methods of mechanics. Biomechanics is a branch of ...
and design of medical and dental implants *
Food science Food science is the basic science and applied science of food; its scope starts at overlap with agricultural science and nutritional science and leads through the scientific aspects of food safety and food processing, informing the developm ...
*
Forensic science Forensic science, also known as criminalistics, is the application of science to criminal and civil laws, mainly—on the criminal side—during criminal investigation, as governed by the legal standards of admissible evidence and criminal ...
* Materials science (composites and foams) *
Nondestructive testing Nondestructive testing (NDT) is any of a wide group of analysis techniques used in science and technology industry to evaluate the properties of a material, component or system without causing damage. The terms nondestructive examination (NDE), n ...
(NDT) *
Paleontology Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
and
functional morphology Functional may refer to: * Movements in architecture: ** Functionalism (architecture) ** Form follows function * Functional group, combination of atoms within molecules * Medical conditions without currently visible organic basis: ** Functional s ...
*
Reverse engineering Reverse engineering (also known as backwards engineering or back engineering) is a process or method through which one attempts to understand through deductive reasoning how a previously made device, process, system, or piece of software accompli ...
*
Soil science Soil science is the study of soil as a natural resource on the surface of the Earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils; and these properties in relation to th ...
*
Petrophysics Petrophysics (from the Greek πέτρα, ''petra'', "rock" and φύσις, ''physis'', "nature") is the study of physical and chemical rock properties and their interactions with fluids. A major application of petrophysics is in studying reservo ...


See also

*
Image segmentation In digital image processing and computer vision, image segmentation is the process of partitioning a digital image into multiple image segments, also known as image regions or image objects ( sets of pixels). The goal of segmentation is to simpl ...


References


External links


Computing-Objects
commercial C++ libraries for mesh generation & FEM computation *
ScanIP Synopsys Simpleware ScanIP is a 3D image processing and model generation software program developed by Synopsys Inc. to visualise, analyse, quantify, segment and export 3D image data from magnetic resonance imaging (MRI), computed tomography ( ...
commercial image-based meshing software
www.simpleware.com
*
Mimics Materialise Mimics is an image processing software for 3D design and modeling, developed by Materialise NV, a Belgian company specialized in additive manufacturing software and technology for medical, dental and additive manufacturing industries ...
3D image-based engineering software for FEA and CFD on anatomical data
Mimics website
* Google group on image-based modelling

* Avizo (software), Avizo Software's 3D image-based meshing tools for CFD and FEA * iso2mesh: a free 3D surface and volumetric mesh generator for matlab/octav


OOF3D
object oriented finite element analysis from the
NIST The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical sci ...

VGSTUDIO MAX
Commercial CT analysis software for industry. They offer an add-on module for FEM meshing. {{DEFAULTSORT:Image-Based Meshing Mesh generation Computer graphics algorithms 3D computer graphics