Vermiculate artefacts in image analysis of granular materials
Journal article, 2016

Some reported analyses of images of deforming granular materials have generated surprising vermiculate strain features which are difficult to reconcile with the mechanics of deformation of granular matter. Detailed investigation using synthetic images and improved processing of images of laboratory experiments indicates that such features can emerge as a consequence of the image acquisition (sensor, contrast, resolution), the subsequent image correlation implementation, and the user’s choice of processing parameters. The two principal factors are: (i) the texture and resolution of the images and (ii) the algorithm used to achieve sub-pixel displacement resolution. Analysis of the images using a sub-pixel interpolation algorithm that is more robust than that used originally eliminates the vermiculate features for images with moderate resolution and texture. However, erroneous features persist in images with low resolution and poor texture. Guidance is provided on ways in which such artefacts can be avoided through improved experimental and image analysis techniques.

Digital image correlation

Granular materials


Sub-pixel interpolation


Sam Stanier

University of Western Australia

Jelke Dijkstra

Chalmers, Civil and Environmental Engineering, GeoEngineering

Danuta Lesniewska

Koszalin University of Technology

Jim Hambleton

University of Newcastle

David White

University of Western Australia

David Muir Wood

Chalmers, Civil and Environmental Engineering, GeoEngineering

University of Western Australia

University of Dundee

Computers and Geotechnics

0266-352X (ISSN)

Vol. 72 100-113

Subject Categories

Geotechnical Engineering



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