Meshing from Image Data with Simpleware

Posted on 20 August 2015 by Philippe Young

Generating accurate meshes from 3D image data (such as MRI and CT) for design and simulation tasks can be a challenge, particularly when working with complex geometries such as the human body, porous media and industrial parts. At Simpleware we have developed software techniques that use image-based meshing to ensure the generation of very high-quality surface and volumetric meshes, which can be used for a wide range of applications. These techniques have also been extended to homogenisation methods for calculating effective material properties, ensuring a fast, easy and reliable bridge from scan to design and simulation-ready models.

Creating a Reliable Mesh: Challenges and Solutions

Alternative approaches to generating a mesh from 3D image data often struggle to generate healthy conforming meshes from complex topologies. It is common for users to have to manually repair meshing errors, particularly for models with gaps or poor overlaps where different structures meet. For software users working with geometries containing multiple parts, this can often be intractable.

Our image-based meshing approach solves these problems by using a range of unique, proprietary algorithms when generating and refining or decimating meshes. A straightforward series of steps can be taken from visualising and segmenting 3D images into regions of interest (ROI) through to carrying out measurements and statistical analysis on images before exporting meshes. The Simpleware method ensures that multiple structures can be robustly meshed by using a unique algorithm that can handle even the most complex geometric structures acquired from 3D image data.

Unique meshing of a three-part junction in Simpleware ScanIP+FE

Unmatched Mesh Quality

Our meshing approach is highly robust and uses proprietary algorithms to generate multi-part meshes directly from image data, while also providing extensive mesh refinement and customisation options for different metrics. The image-based mesher we offer as part of software module +FE is unique in terms of its ability to robustly mesh multiple parts; it can also smooth images without compromising volume or topology, and can handle partial volume effects. We also provide options to re-mesh multi-part surfaces, making it straightforward to reduce the size of a mesh for certain computational tasks, and to refine or decimate localised areas of a model.

The approach is unmatched in terms of accuracy and flexibility for generating surface and volume meshes with conforming interfaces and shared nodes, and reduces the typical process of setting up and repairing meshes. Being able to rapidly generate finite element (FE) or computational fluid dynamics (CFD) meshes from image data means that often intractable tasks – such as generating very complex anatomical models or porous media models with multiple phases - become straightforward. Scripting in the software also means that meshes can be automatically generated.

Multi-part meshing: A) Traditional part-by-part approaches risk poor meshing, gaps/overlaps, non conforming interfaces; B) Simpleware's unique meshing guarantees conforming interfaces and shared nodes

Customising Meshes

In addition, material properties can be assigned, FE shell elements, contact surfaces and node sets added, and features such as boundary layers can be defined for CFD applications. Being able to adaptively re-mesh models allows for customisation to specific metrics, which has been successfully demonstrated in projects such as the human head model developed with the US Naval Research Laboratory. The software's capabilities for generating FE and CFD meshes of nano/microstructure at different length scales also makes it a valuable tool in workflows involving different material samples, such as fuel cellsasphalt and other composites. For 3D printing and Additive Manufacturing, the watertight surface files/STLs generated using our meshing algorithms remove the need for re-meshing and repair before printing.

Unique multi-part mesh decimation algorithms can be used to reduce mesh size whilst preserving accuracy

Doing More with Image-Based Meshing

There are many additional benefits to being able to generate very high-quality, smoothed meshes from 3D image data. Mesh generation techniques have been integrated into software for calculating effective material properties from scanned samples, a method available in our Physics Modules. This is particularly useful for those working with scans of materials such as rock samples and fibre composites who want to quickly obtain statistics and the response of their sample to physics.

A smoothed mesh can be created from a cuboidal sample that does not over-estimate the surface of a model, and can be adaptively re-meshed without compromising volume and topology. Finite element calculations can then be run using generated meshes to obtain effective material properties, such as elasticity, permeability and stiffness. This represents a 'black box' approach, enabling rapid analysis and characterisation of complex material samples.

Comparison of traditional voxel mesh with Simpleware mesh preserving segmented domains without decreasing data resolution

Image-based meshing, and the unique algorithms we have implemented in the software, can be used for any application where it is necessary to create a very robust mesh from image data. Compared to approaches that have limitations when handling multiple parts and smoothing without losing volume or topology, our methods are reliable, easy-to-use and consistent when working with complex 3D image datasets.

Test the quality of our meshes with a free trial of the software, or contact us if you have specific questions about generating models.