Category: image analysis

High precision synthetic computed tomography of reconstructed porous media

Post author By R Hilfer
Post date July 26, 2011

R. Hilfer, T. Zauner

Physical Review E 84, 062301 (2011)
https://doi.org/10.1103/PhysRevE.84.062301

submitted on
Tuesday, July 26, 2011

Multiscale simulation of transport in disordered and porous media requires microstructures covering several decades in length scale. X-ray and synchrotron computed tomography are presently unable to resolve more than one decade of geometric detail. Recent advances in pore scale modeling [Biswal, Held, Khanna, Wang, and Hilfer, Phys. Rev. E 80, 041301 (2009)] provide strongly correlated microstructures with several decades in microstructural detail. A carefully calibrated microstructure model for Fontainebleau sandstone has been discretized into a suite of three-dimensional microstructures with resolutions from roughly 128 μm down to roughly 500 nm. At the highest resolution the three-dimensional image consists of 35 184 372 088 832 discrete cubic volume elements with gray values between 0 and 216. To the best of our knowledge, this synthetic image is the largest computed tomogram of a porous medium available at present.

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image analysis Porous Media

Particle-based Rendering for Porous Media

Post author By R Hilfer
Post date October 28, 2010

S. Grottel, G. Reina, T. Zauner, R. Hilfer, T. Ertl

in: Proceedings of SIGRAD 2010: Content aggregation and visualization
edited by: K. Jää-Aro and T. Larsson
Link{\”o}ping Electronic Conference Proceedings, vol. 52,Link{\”o}ping University Electronic Press, Linköping, 45 (2010)

submitted on
Thursday, October 28, 2010

Particle-based modeling and simulation of granular or porous media is a widely-used tool in physics and material science to study behavior like fracture and failure under external force. Classical models use spherical particles. However, up to 108 polyhedral-shaped particles are required to achieve realistic results comparable to laboratory experiments. As contact points and exposed surfaces play important roles for the analysis, a meaningful visualization aiding the numeric analysis has to represent the exact particle shapes. For particle-based data sets with spherical particles, ray tracing has been established as the state-of-the-art approach yielding high rendering performance, optimal visual quality and good scalability. However, when rendering polyhedral-shaped particles, there is no issue with visual quality comparing polygon-based rendering approaches and ray casting, whereas the polygon-based approaches cause significantly lower fragment load. The paper at hand investigates the advantages and drawbacks of both approaches by analyzing the performance of state-of-the-art rendering methods employing vertex-buffer objects, hardware-supported instancing, geometry shader, and GPU-based ray casting.

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image analysis Porous Media Precision Simulations Simulations

Towards precise prediction of transport properties from synthetic computer tomography of reconstructed porous media

Post author By R Hilfer
Post date April 4, 2009

B. Biswal, R.J. Held, V. Khanna, J. Wang, R. Hilfer

Physical Review E 80, 041301 (2009)
https://doi.org/10.1103/PhysRevE.80.041301

submitted on
Saturday, April 4, 2009

Transport properties of a multiscale carbonate rock are predicted from pore scale models, reconstructed using a continuum geometrical modeling technique. The method combines crystallite information from two-dimensional high-resolution images with sedimentary correlations from a three-dimensional low-resolution microcomputed tomography micro-CT-image to produce a rock sample with calibrated porosity, structural correlation, and transport properties at arbitrary resolutions. Synthetic micro-CT images of the reconstructed model match well with experimental micro-CT images at different resolutions, making it possible to predict physical transport parameters at higher resolutions.

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image analysis Porous Media Simulations

Continuum reconstruction of the pore scale microstructure for Fontainebleau sandstone

Post author By R Hilfer
Post date March 11, 2009

F. Latief, B. Biswal, U. Fauzi, R. Hilfer

Physica A 389, 1607 (2010)
https://doi.org/10.1016/j.physa.2009.12.006

submitted on
Wednesday, March 11, 2009

A stochastic geometrical modeling technique is used to reconstruct a laboratory scale Fontainebleau sandstone with a sidelength of 1.5 cm. The model reconstruction is based on crystallite properties and diagenetic parameters determined from two-dimensional images. The three-dimensional pore scale microstructure of the sandstone is represented by a list of quartz crystallites defined geometrically and placed in the continuum. This allows generation of synthetic μ-CT images of the rock model at arbitrary resolutions. Quantitative microstructure comparison based on Minkowski functionals, two-point correlation function and local porosity theory indicates that this modeling technique can provide more realistic and accurate models of sandstones than many existing techniques used currently. Synthetic μ-CT images at different resolutions from a laboratory scale model of Fon- tainebleau sandstone are made available to the scientific community for resolution dependent petrophysical analysis.

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image analysis Porous Media Simulations

Stochastic Multiscale Model for Carbonate Rocks

Post author By R Hilfer
Post date January 9, 2007

B. Biswal, P.E. Øren, R. Held, S. Bakke, R. Hilfer

Physical Review E 75, 061303 (2007)
https://doi.org/10.1103/PhysRevE.75.061303

submitted on
Tuesday, January 9, 2007

A multiscale model for the diagenesis of carbonate rocks is proposed. It captures important pore scale characteristics of carbonate rocks: wide range of length scales in the pore diameters; large variability in the permeability; and strong dependence of the geometrical and transport parameters on the resolution. A pore scale microstructure of an oolithic dolostone with generic diagenetic features is successfully generated. The continuum representation of a reconstructed cubic sample of sidelength 2 mm contains roughly 42⫻ 106 crystallites and pore diameters varying over many decades. Petrophysical parameters are computed on discretized samples of sizes up to 10003. The model can be easily adapted to represent the multiscale microstructure of a wide variety of carbonate rocks.

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image analysis Porous Media

Characterization of Porous Media by Local Porosities, Minkowski- and Non-Minkowski Functionals

Post author By R Hilfer
Post date April 16, 2004

R. Hilfer

Microscopy and Microanalysis 10, 72 (2004)
DOI: 10.1017/S1431927604884472

submitted on
Friday, April 16, 2004

The presentation reviews local porosity theory. Recent results and new developments are discussed.

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image analysis Porous Media

On the Analysis of Spatial Binary Images

Post author By R Hilfer
Post date March 28, 2000

C. Lang, J. Ohser, R. Hilfer

Journal of Microscopy 203, 303 (2001)
https://doi.org/10.1046/j.1365-2818.2001.00899.x

submitted on
Tuesday, March 28, 2000

This paper deals with the analysis of spatial images taken from microscopically heterogeneous but macroscopically homogeneous microstructures. A new method is presented, which is strictly based on integral‐geometric formulae such as Crofton’s intersection formulae and Hadwiger’s recursive definition of the Euler number. By means of this approach the quermassdensities can be expressed as the inner products of two vectors where the first vector carries the ‘integrated local knowledge’ about the microstructure and the second vector depends on the lateral resolution of the image as well as the quadrature rules used in the discretization of the integral‐geometric formulae. As an example of application we consider the analysis of spatial microtomographic images obtained from natural sandstones.

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image analysis Lattice Models Porous Media

Erosion-Dilation Analysis for Experimental and Synthetic Microstructures of Sedimentary Rock

Post author By R Hilfer
Post date February 17, 2000

A. Tscheschel, D. Stoyan, R. Hilfer

Physica A 284, 46 (2000)
https://doi.org/10.1016/S0378-4371(00)00116-3

submitted on
Thursday, February 17, 2000

Microstructures such as rock samples or simulated structures can be described and characterized by means of ideas of spatial statistics and mathematical morphology. A powerful approach is to transform a given 3D structure by operations of mathematical morphology such as dilation and erosion. This leads to families of structures, for which various characteristics can be determined, for example, porosity, specific connectivity number or correlation and connectivity functions. An application of this idea leads to a clear discrimination between a sample of Fontainebleau sandstone and two simulated samples.

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image analysis Porous Media review article

Review on Scale Dependent Characterization of the Microstructure of Porous Media

Post author By R Hilfer
Post date February 8, 2000

R. Hilfer

Transport in Porous Media 46, 373 (2002)
https://doi.org/10.1023/A:1015014302642

submitted on
Tuesday, February 8, 2000

The paper discusses local porosity theory and its relation with other geometric characterization methods for porous media such as correlation functions and contact distributions. Special emphasis is placed on the charcterization of geometric observables through Hadwigers theorem in stochastic geometry. The four basic Minkowski functionals are introduced into local porosity theory, and for the first time a relationship is established between the Euler characteristic and the local percolation probabilities. Local porosity distributions and local percolation probabilities provide a scale dependent characterization of the microstructure of porous media that can be used in an effective medium approach to predict transport.

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image analysis Porous Media

Quantitative Analysis of Experimental and Synthetic Microstructures for Sedimentary Rock

Post author By R Hilfer
Post date April 17, 1999

B. Biswal, C. Manwart, R. Hilfer, S. Bakke, P.E. Øren

Physica A 273, 452 (1999)
https://doi.org/10.1016/S0378-4371(99)00248-4

submitted on
Monday, May 17, 1999

A quantitative comparison between the experimental microstructure of a sedimentary rock and three theoretical models for the same rock is presented. The microstructure of the rock sample (Fontainebleau sandstone) was obtained by microtomography. Two of the models are stochastic models based on correlation function reconstruction, and one model is based on sedimentation, compaction and diagenesis combined with input from petrographic analysis. The porosity of all models closely match that of the experimental sample and two models have also the same two point correlation function as the experimental sample. We compute quantitative differences and similarities between the various microstructures by a method based on local porosity theory. Differences are found in the degree of anisotropy, and in fluctuations of porosity and connectivity. The stochastic models differ strongly from the real sandstone in their connectivity properties, and hence need further refinement when used to model transport.

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Tags reconstruction models, sediments

image analysis Porous Media Simulations

Microstructure Analysis of Reconstructed Porous Media

Post author By R Hilfer
Post date July 15, 1998

B. Biswal, R. Hilfer

Physica A 266, 307 (1999)
https://doi.org/10.1016/S0378-4371(98)00607-4

submitted on
Wednesday, July 15, 1998

We compare the quantitative microstructural properties of Berea Sandstone with stochastic reconstructions of the same sandstone. The comparison is based on local porosity theory. The reconstructions employ Fourier space filtering of Gaussian random fields and match the average porosity and two-point correlation function of the experimental model. Connectivity properties of the stochastic models differ significantly from the experimental model. Reconstruction models with different levels of coarse graining also show different average local connectivity.

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Tags reconstruction models

image analysis Porous Media Simulations

Threedimensional Local Porosity Analysis of Porous Media

Post author By R Hilfer
Post date February 5, 1998

B. Biswal, C. Manwart, R. Hilfer

Physica A 255, 221 (1998)
https://doi.org/10.1016/S0378-4371(98)00111-3

submitted on
Thursday, February 5, 1998

A quantitative comparison of the pore space geometry for three natural sandstones is presented. The comparison is based on local porosity theory which provides a geometric characterization of stochastic microstructures. The characterization focusses on porosity and connectivity fluctuations. Porosity fluctuations are measured using local porosity distributions while connectivity fluctuations are measured using local percolation probabilities. We report the first measurement of local percolation probability functions for experimentally obtained three-dimensional pore space reconstructions. Our results suggest the use of local porosity distributions and percolation probabilities as a quantitative method to compare microstructures of models and experiment.

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Tags local porosity theory