Computer axial tomography in geosciences: an overview

Duliu, Octavian G.

doi:10.1016/s0012-8252(99)00056-2

Cited by 149 publications

(86 citation statements)

References 72 publications

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“…Commonly experienced problems include high-frequency noise, beam hardening, defective detector pixels, scattered x rays or poorly centered samples [Stock, 1999;Duliu, 1999;Ikeda et al, 2000;Van Geet et al, 2000;Ketcham and Carlson, 2001;Wildenschild et al, 2002]. In addition, there might be errors and distortions from CT reconstruction.…”

Section: Introductionmentioning

confidence: 99%

Segmentation of X‐ray computed tomography images of porous materials: A crucial step for characterization and quantitative analysis of pore structures

Iassonov

Gebrenegus

Tuller

2009

Water Resources Research

507

332

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[1] Nondestructive imaging methods such as X-ray computed tomography (CT) yield high-resolution, three-dimensional representations of pore space and fluid distribution within porous materials. Steadily increasing computational capabilities and easier access to X-ray CT facilities have contributed to a recent surge in microporous media research with objectives ranging from theoretical aspects of fluid and interfacial dynamics at the pore scale to practical applications such as dense nonaqueous phase liquid transport and dissolution. In recent years, significant efforts and resources have been devoted to improve CT technology, microscale analysis, and fluid dynamics simulations. However, the development of adequate image segmentation methods for conversion of gray scale CT volumes into a discrete form that permits quantitative characterization of pore space features and subsequent modeling of liquid distribution and flow processes seems to lag. In this paper we investigated the applicability of various thresholding and locally adaptive segmentation techniques for industrial and synchrotron X-ray CT images of natural and artificial porous media. A comparison between directly measured and image-derived porosities clearly demonstrates that the application of different segmentation methods as well as associated operator biases yield vastly differing results. This illustrates the importance of the segmentation step for quantitative pore space analysis and fluid dynamics modeling. Only a few of the tested methods showed promise for both industrial and synchrotron tomography. Utilization of local image information such as spatial correlation as well as the application of locally adaptive techniques yielded significantly better results.Citation: Iassonov, P., T. Gebrenegus, and M. Tuller (2009), Segmentation of X-ray computed tomography images of porous materials: A crucial step for characterization and quantitative analysis of pore structures, Water Resour. Res., 45, W09415,

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Section: Introductionmentioning

confidence: 99%

Segmentation of X‐ray computed tomography images of porous materials: A crucial step for characterization and quantitative analysis of pore structures

Iassonov

Gebrenegus

Tuller

2009

Water Resources Research

507

332

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“…It gives not only a 3D picture of the sedimentary structures but also natural heterogeneities (fissures, inclusions, cavities) and allows selection of high-quality specimens for laboratory testing. CAT imaging is based on Beer's law that relates the incident intensity (I 0 ) and transmitted intensity (I) of a X-ray or gamma-ray beam passing over an entire transverse section by means of a linear attenuation coefficient (l) (e.g., [16]):…”

Section: Image Analysismentioning

confidence: 99%

Getting high-quality samples in ‘sensitive’ soils for advanced laboratory tests

Fonseca

Pineda

2017

Innov. Infrastruct. Solut.

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Laboratory tests are well recognized as highly appropriate for defining the engineering properties of geomaterials, in terms of constitutive law parameters for modeling geotechnical engineering problems. The strong development of advanced techniques, both in equipment and in data interpretation, has increased the confidence in laboratory testing, while on the other hand the limitations due to the quality of soil sampling with depth and the spatial representativeness of the samples are less consensual. Still, the development of new methods for assuring high-quality samples is increasing, together with sampling quality assessment by non-destructive methods using vibration wave velocities. Interpretation methods of in situ tests for ground characterization have also evolved significantly, increasing the reliability of these methods. Their versatility to cover large areas on site and the fact that these tests are, in principle, performed at the actual state (physical and stress) conditions, as well as the improvements in the correlations between field tests and hydraulic and geomechanical parameters, allow joining the quality of data and theoretical approaches, namely through critical state soil mechanics. This keynote paper discusses some of the aspects that can and should enable the association of ground characterization from laboratory testing over undisturbed samples used in more or less advanced tests, enhancing the determinant conditioning factor, that is, the sampling technique to get representative specimens and the way this is assessed. The confidence that we expect to have on the geomechanical parameters that we need for our geotechnical activities will mostly depend on this in view of the high uncertainties of the parametrical correlations with in situ test data, therefore, important in ground characterization. This is especially relevant in sensitive soils, such as soft fine soils, loose sandy soils, or young residuals soils. These have or can have ''weak'' equilibria of the interparticle micro-and macrostructures (or their arrangement, fabric) that will change substantially their properties if samples are collected and conditioned with processes that do not preserve that intrinsic ''ADN''. The change in these natural conditions can be evaluated by techniques of quality assessment, which will be discussed in what follows.

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“…Consequently, CT-Scanner can be used to measure the relative density of materials such as sand layers in sedimentological studies (Duliu 1999, Ketcham and Carlson 2001, Duchesne et al 2006, Mees et al 2003. Relative density values vary from -1024 to +3071 Hounsfield units (HU) (Kak and Slaney 1999).…”

Section: Laboratory Experimentsmentioning

confidence: 99%

Airborne Lidar Bathymetry Applied to Coastal Hydrodynamic Processes

Long¹,

Aucoin²,

Montreuil³

et al. 2011

Int. Conf. Coastal. Eng.

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In this study, the possibility to get sedimentological (density, compaction) and hydrodynamical (suspended sediment concentration, turbulence) information from ALB surveys is demonstrated. ALB laser reflectance was found to be higher on the lee-side and on the crest of the ripple bedform than in the trough and on the stoss-side. Moreover, laser reflectance was also found to be higher on "active" subtidal dunes, located within the depth of action of the waves, than on deeper "passive" bedforms. Based on lab experiments conducted in a hydraulic flume under X-ray CT-Scanner, these observations were related to sediment compaction and suspended sediment.

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Computer axial tomography in geosciences: an overview

Cited by 149 publications

References 72 publications

Segmentation of X‐ray computed tomography images of porous materials: A crucial step for characterization and quantitative analysis of pore structures

Segmentation of X‐ray computed tomography images of porous materials: A crucial step for characterization and quantitative analysis of pore structures

Getting high-quality samples in ‘sensitive’ soils for advanced laboratory tests

Airborne Lidar Bathymetry Applied to Coastal Hydrodynamic Processes

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