TY - CHAP A1 - Homberg, Ulrike A1 - Baum, Daniel A1 - Prohaska, Steffen A1 - Kalbe, Ute A1 - Witt, Karl Josef T1 - Automatic Extraction and Analysis of Realistic Pore Structures from µCT Data for Pore Space Characterization of Graded Soil T2 - Proceedings of the 6th International Conference on Scour and Erosion (ICSE-6) Y1 - 2012 SP - 345 EP - 352 ER - TY - GEN A1 - Homberg, Ulrike A1 - Baum, Daniel A1 - Wiebel, Alexander A1 - Prohaska, Steffen A1 - Hege, Hans-Christian ED - Bremer, Peer-Timo ED - Hotz, Ingrid ED - Pascucci, Valerio ED - Peikert, Ronald T1 - Definition, Extraction, and Validation of Pore Structures in Porous Materials BT - Theory, Algorithms, and Applications T2 - Topological Methods in Data Analysis and Visualization III Y1 - 2014 U6 - https://doi.org/10.1007/978-3-319-04099-8_15 SP - 235 EP - 248 PB - Springer ER - TY - CHAP A1 - Homberg, Ulrike A1 - Binner, Richard A1 - Prohaska, Steffen A1 - Dercksen, Vincent J. A1 - Kuß, Anja A1 - Kalbe, Ute T1 - Determining Geometric Grain Structure from X-Ray Micro-Tomograms of Gradated Soil T2 - Workshop Internal Erosion Y1 - 2009 VL - 21 SP - 37 EP - 52 ER - TY - GEN A1 - Homberg, Ulrike A1 - Baum, Daniel A1 - Wiebel, Alexander A1 - Prohaska, Steffen A1 - Hege, Hans-Christian T1 - Definition, Extraction, and Validation of Pore Structures in Porous Materials N2 - An intuitive and sparse representation of the void space of porous materials supports the efficient analysis and visualization of interesting qualitative and quantitative parameters of such materials. We introduce definitions of the elements of this void space, here called pore space, based on its distance function, and present methods to extract these elements using the extremal structures of the distance function. The presented methods are implemented by an image processing pipeline that determines pore centers, pore paths and pore constrictions. These pore space elements build a graph that represents the topology of the pore space in a compact way. The representations we derive from μCT image data of realistic soil specimens enable the computation of many statistical parameters and, thus, provide a basis for further visual analysis and application-specific developments. We introduced parts of our pipeline in previous work. In this chapter, we present additional details and compare our results with the analytic computation of the pore space elements for a sphere packing in order to show the correctness of our graph computation. T3 - ZIB-Report - 13-56 Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-42510 SN - 1438-0064 ER - TY - GEN A1 - Homberg, Ulrike A1 - Baum, Daniel A1 - Prohaska, Steffen A1 - Günster, Jens A1 - Krauß-Schüler, Stefanie T1 - Adapting trabecular structures for 3D printing: an image processing approach based on µCT data N2 - Materials with a trabecular structure notably combine advantages such as lightweight, reasonable strength, and permeability for fluids. This combination of advantages is especially interesting for tissue engineering in trauma surgery and orthopedics. Bone-substituting scaffolds for instance are designed with a trabecular structure in order to allow cell migration for bone ingrowth and vascularization. An emerging and recently very popular technology to produce such complex, porous structures is 3D printing. However, several technological aspects regarding the scaffold architecture, the printable resolution, and the feature size have to be considered when fabricating scaffolds for bone tissue replacement and regeneration. Here, we present a strategy to assess and prepare realistic trabecular structures for 3D printing using image analysis with the aim of preserving the structural elements. We discuss critical conditions of the printing system and present a 3-stage approach to adapt a trabecular structure from $\mu$CT data while incorporating knowledge about the printing system. In the first stage, an image-based extraction of solid and void structures is performed, which results in voxel- and graph-based representations of the extracted structures. These representations not only allow us to quantify geometrical properties such as pore size or strut geometry and length. But, since the graph represents the geometry and the topology of the initial structure, it can be used in the second stage to modify and adjust feature size, volume and sample size in an easy and consistent way. In the final reconstruction stage, the graph is then converted into a voxel representation preserving the topology of the initial structure. This stage generates a model with respect to the printing conditions to ensure a stable and controlled voxel placement during the printing process. T3 - ZIB-Report - 17-26 KW - trabecular structures KW - image-based analysis KW - additive manufacturing KW - printability Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-64004 SN - 1438-0064 ER - TY - JOUR A1 - Homberg, Ulrike A1 - Baum, Daniel A1 - Prohaska, Steffen A1 - Günster, Jens A1 - Krauß-Schüler, Stefanie T1 - Adapting trabecular structures for 3D printing: an image processing approach based on µCT data JF - Biomedical Physics & Engineering Express N2 - Materials with a trabecular structure notably combine advantages such as lightweight, reasonable strength, and permeability for fluids. This combination of advantages is especially interesting for tissue engineering in trauma surgery and orthopedics. Bone-substituting scaffolds for instance are designed with a trabecular structure in order to allow cell migration for bone ingrowth and vascularization. An emerging and recently very popular technology to produce such complex, porous structures is 3D printing. However, several technological aspects regarding the scaffold architecture, the printable resolution, and the feature size have to be considered when fabricating scaffolds for bone tissue replacement and regeneration. Here, we present a strategy to assess and prepare realistic trabecular structures for 3D printing using image analysis with the aim of preserving the structural elements. We discuss critical conditions of the printing system and present a 3-stage approach to adapt a trabecular structure from $\mu$CT data while incorporating knowledge about the printing system. In the first stage, an image-based extraction of solid and void structures is performed, which results in voxel- and graph-based representations of the extracted structures. These representations not only allow us to quantify geometrical properties such as pore size or strut geometry and length. But, since the graph represents the geometry and the topology of the initial structure, it can be used in the second stage to modify and adjust feature size, volume and sample size in an easy and consistent way. In the final reconstruction stage, the graph is then converted into a voxel representation preserving the topology of the initial structure. This stage generates a model with respect to the printing conditions to ensure a stable and controlled voxel placement during the printing process. Y1 - 2017 U6 - https://doi.org/10.1088/2057-1976/aa7611 VL - 3 IS - 3 PB - IOP Publishing ER - TY - CHAP A1 - Seblany, Feda A1 - Homberg, Ulrike A1 - Vincens, Eric A1 - Winkler, Paul A1 - Witt, Karl Josef T1 - Merging criteria for the definition of a local pore and the CSD computation of granular materials T2 - Proceedings of the 25th meeting of the Working Group on Internal Erosion in embankment dams and their foundations Y1 - 2017 SN - 978-90-827468-1-5 | 978-90-827468-0-8 SP - 150 EP - 159 PB - Deltares CY - Delft, Netherlands ER - TY - GEN A1 - Seblany, Feda A1 - Homberg, Ulrike A1 - Vincens, Eric A1 - Winkler, Paul A1 - Witt, Karl Josef T1 - Merging criteria for the definition of a local pore and the CSD computation of granular materials T3 - ZIB-Report - 18-09 Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-67069 SN - 1438-0064 ER - TY - JOUR A1 - Vincens, Eric A1 - Witt, Karl Josef A1 - Homberg, Ulrike T1 - Approaches to Determine the Constriction Size Distribution for Understanding Filtration Phenomena in Granular Materials JF - Acta Geotechnica Y1 - 2015 U6 - https://doi.org/10.1007/s11440-014-0308-1 VL - 10 IS - 3 SP - 291 EP - 303 PB - Springer ER - TY - CHAP A1 - Mehlhorn, Tobias A1 - Prohaska, Steffen A1 - Homberg, Ulrike A1 - Slowik, Volker T1 - Modelling and Analysis of Particle and Pore Structures in Soils T2 - Workshop Internal Erosion Y1 - 2009 VL - 21 SP - 53 EP - 60 ER - TY - CHAP A1 - Semar, Olivier A1 - Binner, Richard A1 - Homberg, Ulrike A1 - Kalbe, Ute A1 - Mehlhorn, Tobias A1 - Prohaska, Steffen A1 - Slowik, Volker A1 - Witt, Karl Josef T1 - Conditions for Suffosive Erosion Phemomena in Soils – Concept and Approach T2 - Workshop Internal Erosion Y1 - 2009 VL - 21 SP - 29 EP - 35 ER - TY - CHAP A1 - Homberg, Ulrike A1 - Baum, Daniel A1 - Prohaska, Steffen ED - Mücklich, Frank ED - Slussallek, Philipp ED - Schladitz, Katja T1 - Describing and Analyzing the Dual Structures of Porous Media T2 - Proc. 3D-Microstructure Meeting Y1 - 2011 SP - 24 EP - 25 ER - TY - GEN A1 - Vincens, Eric A1 - Witt, Karl Josef A1 - Homberg, Ulrike T1 - Approaches to Determine the Constriction Size Distribution for Understanding Filtration Phenomena in Granular Materials N2 - Granular filters in hydraulically loaded earth structures constitute the ultimate barrier for the blockage of small particles moving through the structure regularly or along concentrated leaks. If filters are inefficient to block small particles several types of internal erosion may be initiated. A corresponding phenomenon appears during suffusion in a wide graded hydraulically loaded fill, when fine particles, embedded in the pore structure of a soil skeleton, are washed out. The cumulative constriction size distribution (CSD) is physically the key property that qualifies the soils retention capability as like a spatial acting sieve. Constrictions are defined as the narrowest sections of channels between larger volumes (pores) within the pore network of granular material and they are the main obstacles for a small particle to overcome when flowing along pathways. At least three different approaches are available to determine and compute the CSD, i.e. experimental, numerical and analytical methods. The purpose of this review is to present and discuss these methods pointing out their limits, advantages and significance related to internal erosion phenomena. T3 - ZIB-Report - 14-01 Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-43960 SN - 1438-0064 ER - TY - CHAP A1 - Binner, Richard A1 - Homberg, Ulrike A1 - Prohaska, Steffen A1 - Kalbe, Ute A1 - Witt, Karl Josef T1 - Identification of Descriptive Parameters of the Soil Pore Structure using Experiments and CT Data T2 - Proceedings of the 5th International Conference on Scour and Erosion (ICSE-5) Y1 - 2010 SP - 397 EP - 407 PB - American Society of Civil Engineers (ASCE) ER - TY - JOUR A1 - Seblany, Feda A1 - Homberg, Ulrike A1 - Vincens, Eric A1 - Winkler, Paul A1 - Witt, Karl Josef T1 - Merging criteria for defining pores and constrictions in numerical packing of spheres JF - Granular Matter N2 - The void space of granular materials is generally divided into larger local volumes denoted as pores and throats connecting pores. The smallest section in a throat is usually denoted as constriction. A correct description of pores and constrictions may help to understand the processes related to the transport of fluid or fine particles through granular materials, or to build models of imbibition for unsaturated granular media. In the case of numerical granular materials involving packings of spheres, different methods can be used to compute the pore space properties. However, these methods generally induce an over-segmentation of the pore network and a merging step is usually applied to mitigate such undesirable artifacts even if a precise delineation of a pore is somewhat subjective. This study provides a comparison between different merging criteria for pores in packing of spheres and a discussion about their implication on both the pore size distribution and the constriction size distribution of the material. A correspondence between these merging techniques is eventually proposed as a guide for the user. Y1 - 2018 U6 - https://doi.org/10.1007/s10035-018-0808-z SN - 1434-5021 SN - 1434-7636 VL - 20 IS - 37 PB - Springer Berlin Heidelberg ER - TY - GEN A1 - Seblany, Feda A1 - Homberg, Ulrike A1 - Vincens, Eric A1 - Winkler, Paul A1 - Witt, Karl Josef T1 - Merging criteria for defining pores and constrictions in numerical packing of spheres N2 - The void space of granular materials is generally divided into larger local volumes denoted as pores and throats connecting pores. The smallest section in a throat is usually denoted as constriction. A correct description of pores and constrictions may help to understand the processes related to the transport of fluid or fine particles through granular materials, or to build models of imbibition for unsaturated granular media. In the case of numerical granular materials involving packings of spheres, different methods can be used to compute the pore space properties. However, these methods generally induce an over-segmentation of the pore network and a merging step is usually applied to mitigate such undesirable artifacts even if a precise delineation of a pore is somewhat subjective. This study provides a comparison between different merging criteria for pores in packing of spheres and a discussion about their implication on both the pore size distribution and the constriction size distribution of the material. A correspondence between these merging techniques is eventually proposed as a guide for the user. T3 - ZIB-Report - 18-25 Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-69158 SN - 1438-0064 ER -