Image-based meshing
Encyclopedia
Image-based meshing is the automated process of creating computer models for computational fluid dynamics
(CFD) and finite element analysis
(FEA) from 3D image data (such as magnetic resonance imaging
(MRI), computed tomography
(CT) or microtomography
). Although a wide range of mesh generation techniques are currently available, these were usually developed to generate models from computer-aided design
(CAD), and have therefore difficulties meshing from 3D imaging data.
Another approach generates 3D hexahedral or tetrahedral elements throughout the volume of the domain, thus creating the mesh directly with conforming multipart surfaces.
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:
Computational fluid dynamics
Computational fluid dynamics, usually abbreviated as CFD, is a branch of fluid mechanics that uses numerical methods and algorithms to solve and analyze problems that involve fluid flows. Computers are used to perform the calculations required to simulate the interaction of liquids and gases with...
(CFD) and finite element analysis
Finite element method
The finite element method is a numerical technique for finding approximate solutions of partial differential equations as well as integral equations...
(FEA) from 3D image data (such as magnetic resonance imaging
Magnetic resonance imaging
Magnetic resonance imaging , nuclear magnetic resonance imaging , or magnetic resonance tomography is a medical imaging technique used in radiology to visualize detailed internal structures...
(MRI), computed tomography
Computed tomography
X-ray computed tomography or Computer tomography , is a medical imaging method employing tomography created by computer processing...
(CT) or microtomography
Microtomography
Microtomography , like tomography, uses x-rays to create cross-sections of a 3D-object that later can be used to recreate a virtual model without destroying the original model....
). 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
Computer-aided design , also known as computer-aided design and drafting , is the use of computer technology for the process of design and design-documentation. Computer Aided Drafting describes the process of drafting with a computer...
(CAD), and have therefore 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 hexahedral or tetrahedral elements throughout the volume of the domain, thus creating the mesh directly with conforming multipart surfaces.
Scan and image processing
An extensive range of image processingImage processing
In electrical engineering and computer science, image processing is any form of signal processing for which the input is an image, such as a photograph or video frame; the output of image processing may be either an image or, a set of characteristics or parameters related to the image...
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 toolsSegmentation (image processing)In computer vision, segmentation refers to the process of partitioning a digital image into multiple segments . The goal of segmentation is to simplify and/or change the representation of an image into something that is more meaningful and easier to analyze...
(e.g. thresholding, floodfill, level set methods, etc.) - Filters and smoothing toolsSmoothingIn statistics and image processing, to smooth a data set is to create an approximating function that attempts to capture important patterns in the data, while leaving out noise or other fine-scale structures/rapid phenomena. Many different algorithms are used in smoothing...
(e.g. volume- and topology-preserving smoothing).
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 modulusYoung's modulusYoung's modulus is a measure of the stiffness of an elastic material and is a quantity used to characterize materials. It is defined as the ratio of the uniaxial stress over the uniaxial strain in the range of stress in which Hooke's Law holds. In solid mechanics, the slope of the stress-strain...
to Hounsfield scaleHounsfield scaleThe Hounsfield scale, named after Sir Godfrey Newbold Hounsfield, is a quantitative scale for describing radiodensity.-Definition:The Hounsfield unit scale is a linear transformation of the original linear attenuation coefficient measurement into one in which the radiodensity of distilled water at...
) - 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. nodes, elements, material properties, contact surfaces)
Typical use
- BiomechanicsBiomechanicsBiomechanics is the application of mechanical principles to biological systems, such as humans, animals, plants, organs, and cells. Perhaps one of the best definitions was provided by Herbert Hatze in 1974: "Biomechanics is the study of the structure and function of biological systems by means of...
and design of medical and dental implantsImplant (medicine)An implant is a medical device manufactured to replace a missing biological structure, support a damaged biological structure, or enhance an existing biological structure. Medical implants are man-made devices, in contrast to a transplant, which is a transplanted biomedical tissue... - Food scienceFood scienceFood science is a study concerned with all technical aspects of foods, beginning with harvesting or slaughtering, and ending with its cooking and consumption, an ideology commonly referred to as "from field to fork"...
- Forensic science
- Materials scienceMaterials scienceMaterials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It incorporates...
(composites and foams) - Nondestructive testingNondestructive testingNondestructive testing or Non-destructive testing is a wide group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing damage....
(NDT) - PaleontologyPaleontologyPaleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
and functional morphologyMorphology (biology)In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features.... - Reverse engineeringReverse engineeringReverse engineering is the process of discovering the technological principles of a device, object, or system through analysis of its structure, function, and operation...
- Soil scienceSoil scienceSoil 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 the use and management of soils.Sometimes terms which...
and petrologyPetrologyPetrology is the branch of geology that studies rocks, and the conditions in which rocks form....
External links
- MimicsMimicsMimics is an image processing software for 3D design and modeling, developed by Materialise NV, a Belgian company specialized in additive manufacturing software and technology. Mimics is used to create 3D surface models from stacks of 2D image data. These 3D models can then be used for a variety of...
3D image-based engineering software for FEA and CFD on anatomical data: Mimics website - Simpleware commercial image-based meshing software: www.simpleware.com
- Google group on image-based modelling: http://groups.google.co.uk/group/image-based-modelling
- Avizo SoftwareAvizo (software)Avizo is a general-purpose commercial software application for scientific and industrial data visualization and analysis....
'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/