TY - JOUR A1 - Titschack, Jürgen A1 - Baum, Daniel A1 - Matsuyama, Kei A1 - Boos, Karin A1 - Färber, Claudia A1 - Kahl, Wolf-Achim A1 - Ehrig, Karsten A1 - Meinel, Dietmar A1 - Soriano, Carmen A1 - Stock, Stuart R. T1 - Ambient occlusion – a powerful algorithm to segment shell and skeletal intrapores in computed tomography data JF - Computers and Geosciences N2 - During the last decades, X-ray (micro-)computed tomography has gained increasing attention for the description of porous skeletal and shell structures of various organism groups. However, their quantitative analysis is often hampered by the difficulty to discriminate cavities and pores within the object from the surrounding region. Herein, we test the ambient occlusion (AO) algorithm and newly implemented optimisations for the segmentation of cavities (implemented in the software Amira). The segmentation accuracy is evaluated as a function of (i) changes in the ray length input variable, and (ii) the usage of AO (scalar) field and other AO-derived (scalar) fields. The results clearly indicate that the AO field itself outperforms all other AO-derived fields in terms of segmentation accuracy and robustness against variations in the ray length input variable. The newly implemented optimisations improved the AO field-based segmentation only slightly, while the segmentations based on the AO-derived fields improved considerably. Additionally, we evaluated the potential of the AO field and AO-derived fields for the separation and classification of cavities as well as skeletal structures by comparing them with commonly used distance-map-based segmentations. For this, we tested the zooid separation within a bryozoan colony, the stereom classification of an ophiuroid tooth, the separation of bioerosion traces within a marble block and the calice (central cavity)-pore separation within a dendrophyllid coral. The obtained results clearly indicate that the ideal input field depends on the three-dimensional morphology of the object of interest. The segmentations based on the AO-derived fields often provided cavity separations and skeleton classifications that were superior to or impossible to obtain with commonly used distance- map-based segmentations. The combined usage of various AO-derived fields by supervised or unsupervised segmentation algorithms might provide a promising target for future research to further improve the results for this kind of high-end data segmentation and classification. Furthermore, the application of the developed segmentation algorithm is not restricted to X-ray (micro-)computed tomographic data but may potentially be useful for the segmentation of 3D volume data from other sources. Y1 - 2018 U6 - https://doi.org/10.1016/j.cageo.2018.03.007 VL - 115 SP - 75 EP - 87 ER - TY - GEN A1 - Titschack, Jürgen A1 - Baum, Daniel A1 - Matsuyama, Kei A1 - Boos, Karin A1 - Färber, Claudia A1 - Kahl, Wolf-Achim A1 - Ehrig, Karsten A1 - Meinel, Dietmar A1 - Soriano, Carmen A1 - Stock, Stuart R. T1 - Ambient occlusion – a powerful algorithm to segment shell and skeletal intrapores in computed tomography data N2 - During the last decades, X-ray (micro-)computed tomography has gained increasing attention for the description of porous skeletal and shell structures of various organism groups. However, their quantitative analysis is often hampered by the difficulty to discriminate cavities and pores within the object from the surrounding region. Herein, we test the ambient occlusion (AO) algorithm and newly implemented optimisations for the segmentation of cavities (implemented in the software Amira). The segmentation accuracy is evaluated as a function of (i) changes in the ray length input variable, and (ii) the usage of AO (scalar) field and other AO-derived (scalar) fields. The results clearly indicate that the AO field itself outperforms all other AO-derived fields in terms of segmentation accuracy and robustness against variations in the ray length input variable. The newly implemented optimisations improved the AO field-based segmentation only slightly, while the segmentations based on the AO-derived fields improved considerably. Additionally, we evaluated the potential of the AO field and AO-derived fields for the separation and classification of cavities as well as skeletal structures by comparing them with commonly used distance-map-based segmentations. For this, we tested the zooid separation within a bryozoan colony, the stereom classification of an ophiuroid tooth, the separation of bioerosion traces within a marble block and the calice (central cavity)-pore separation within a dendrophyllid coral. The obtained results clearly indicate that the ideal input field depends on the three-dimensional morphology of the object of interest. The segmentations based on the AO-derived fields often provided cavity separations and skeleton classifications that were superior to or impossible to obtain with commonly used distance- map-based segmentations. The combined usage of various AO-derived fields by supervised or unsupervised segmentation algorithms might provide a promising target for future research to further improve the results for this kind of high-end data segmentation and classification. Furthermore, the application of the developed segmentation algorithm is not restricted to X-ray (micro-)computed tomographic data but may potentially be useful for the segmentation of 3D volume data from other sources. T3 - ZIB-Report - 18-14 Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-67982 SN - 1438-0064 ER - TY - JOUR A1 - Taylor, William R. A1 - Pöpplau, Berry M. A1 - König, Christian A1 - Ehrig, Rainald A1 - Zachow, Stefan A1 - Duda, Georg A1 - Heller, Markus O. T1 - The medial-lateral force distribution in the ovine stifle joint during walking JF - Journal of Orthopaedic Research Y1 - 2011 U6 - https://doi.org/10.1002/jor.21254 VL - 29 IS - 4 SP - 567 EP - 571 ER - TY - CHAP A1 - Taylor, William R. A1 - König, Christian A1 - Speirs, A. A1 - Ehrig, Rainald A1 - Duda, G. A1 - Heller, Markus O. T1 - The medio-lateral force distribution in the sheep knee during walking T2 - 5. World Congress of Biomechanics, Munich, Journal of Biomechanics Y1 - 2006 IS - 39, Suppl. 1 SP - S491 ER - TY - CHAP A1 - Taylor, William R. A1 - König, Christian A1 - Speirs, A. A1 - Ehrig, Rainald A1 - Duda, G. A1 - Heller, Markus O. T1 - Die medio-laterale Kraftverteilung im Schafsknie T2 - Deutscher Kongress für Orthpädie und Unfallchirurgie, Berlin Y1 - 2006 ER - TY - CHAP A1 - Taylor, William R. A1 - Kratzenstein, Stefan A1 - Kornaropoulos, Evgenios I. A1 - Ehrig, Rainald A1 - Moewis, Philippe A1 - Heller, Markus O. T1 - Non-invasive Assessment of Skeletal Kinematics T2 - Measurement and Sensing in Medicine and Health Y1 - 2009 CY - London ER - TY - CHAP A1 - Taylor, William R. A1 - Kornaropoulos, Evgenios I. A1 - Kratzenstein, Stefan A1 - Ehrig, Rainald A1 - Plank, F. A1 - Heller, Markus O. T1 - Targeted Marker Placement for the Functional Identification of the Hip Joint Centre T2 - Transactions Vol. 36, 2011 Annual Meeting of the Orthopedic Society Y1 - 2011 CY - Long Beach ER - TY - CHAP A1 - Taylor, William R. A1 - Kornaropoulos, Evgenios I. A1 - Ehrig, Rainald A1 - Heller, Markus O. A1 - Duda, Georg T1 - Reproducibility of a functional approach to gait analysis T2 - Annual meeting of the ESMAC 2009 Y1 - 2009 CY - London ER - TY - CHAP A1 - Taylor, William R. A1 - Kassi, J.-P. A1 - Schwarzkopf, J. A1 - Ehrig, Rainald A1 - Schell, H. A1 - Duda, G. T1 - The Profile of Mechanical Loading is Independent of Fracture Fixation Principle T2 - Proceedings of the 51th Annual Meeting of the Orthopedic Society Y1 - 2005 CY - Washington ER - TY - CHAP A1 - Taylor, William R. A1 - Fröhlich, Annika A1 - Buttgereit, Frank A1 - Ehrig, Rainald A1 - Witaschek, Tom A1 - Duda, Georg ED - Kersting, Uwe ED - Morlock, Michael ED - Jirova-Enzmann, Daniela ED - Dremstrup, Kim T1 - Metacarpophalangeal joint stiffness is reduced in patients affected by rheumatoid arthritis after glucocorticoid medication T2 - Proceedings of the ESM-2012, Aalborg Y1 - 2012 SP - 39 PB - Department of Health Science and Technology, Aalborg University ER -