@article{TitschackBaumMatsuyamaetal.2018, author = {Titschack, J{\"u}rgen and Baum, Daniel and Matsuyama, Kei and Boos, Karin and F{\"a}rber, Claudia and Kahl, Wolf-Achim and Ehrig, Karsten and Meinel, Dietmar and Soriano, Carmen and Stock, Stuart R.}, title = {Ambient occlusion - a powerful algorithm to segment shell and skeletal intrapores in computed tomography data}, series = {Computers and Geosciences}, volume = {115}, journal = {Computers and Geosciences}, doi = {10.1016/j.cageo.2018.03.007}, pages = {75 -- 87}, year = {2018}, abstract = {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.}, language = {en} } @misc{TitschackBaumMatsuyamaetal., author = {Titschack, J{\"u}rgen and Baum, Daniel and Matsuyama, Kei and Boos, Karin and F{\"a}rber, Claudia and Kahl, Wolf-Achim and Ehrig, Karsten and Meinel, Dietmar and Soriano, Carmen and Stock, Stuart R.}, title = {Ambient occlusion - a powerful algorithm to segment shell and skeletal intrapores in computed tomography data}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-67982}, abstract = {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.}, language = {en} } @article{TaylorPoepplauKoenigetal.2011, author = {Taylor, William R. and P{\"o}pplau, Berry M. and K{\"o}nig, Christian and Ehrig, Rainald and Zachow, Stefan and Duda, Georg and Heller, Markus O.}, title = {The medial-lateral force distribution in the ovine stifle joint during walking}, series = {Journal of Orthopaedic Research}, volume = {29}, journal = {Journal of Orthopaedic Research}, number = {4}, doi = {10.1002/jor.21254}, pages = {567 -- 571}, year = {2011}, language = {en} } @inproceedings{TaylorKoenigSpeirsetal.2006, author = {Taylor, William R. and K{\"o}nig, Christian and Speirs, A. and Ehrig, Rainald and Duda, G. and Heller, Markus O.}, title = {The medio-lateral force distribution in the sheep knee during walking}, series = {5. World Congress of Biomechanics, Munich, Journal of Biomechanics}, booktitle = {5. World Congress of Biomechanics, Munich, Journal of Biomechanics}, number = {39, Suppl. 1}, pages = {S491}, year = {2006}, language = {en} } @inproceedings{TaylorKoenigSpeirsetal.2006, author = {Taylor, William R. and K{\"o}nig, Christian and Speirs, A. and Ehrig, Rainald and Duda, G. and Heller, Markus O.}, title = {Die medio-laterale Kraftverteilung im Schafsknie}, series = {Deutscher Kongress f{\"u}r Orthp{\"a}die und Unfallchirurgie, Berlin}, booktitle = {Deutscher Kongress f{\"u}r Orthp{\"a}die und Unfallchirurgie, Berlin}, year = {2006}, language = {en} } @inproceedings{TaylorKratzensteinKornaropoulosetal.2009, author = {Taylor, William R. and Kratzenstein, Stefan and Kornaropoulos, Evgenios I. and Ehrig, Rainald and Moewis, Philippe and Heller, Markus O.}, title = {Non-invasive Assessment of Skeletal Kinematics}, series = {Measurement and Sensing in Medicine and Health}, booktitle = {Measurement and Sensing in Medicine and Health}, address = {London}, year = {2009}, language = {en} } @inproceedings{TaylorKornaropoulosKratzensteinetal.2011, author = {Taylor, William R. and Kornaropoulos, Evgenios I. and Kratzenstein, Stefan and Ehrig, Rainald and Plank, F. and Heller, Markus O.}, title = {Targeted Marker Placement for the Functional Identification of the Hip Joint Centre}, series = {Transactions Vol. 36, 2011 Annual Meeting of the Orthopedic Society}, booktitle = {Transactions Vol. 36, 2011 Annual Meeting of the Orthopedic Society}, address = {Long Beach}, year = {2011}, language = {en} } @inproceedings{TaylorKornaropoulosEhrigetal.2009, author = {Taylor, William R. and Kornaropoulos, Evgenios I. and Ehrig, Rainald and Heller, Markus O. and Duda, Georg}, title = {Reproducibility of a functional approach to gait analysis}, series = {Annual meeting of the ESMAC 2009}, booktitle = {Annual meeting of the ESMAC 2009}, address = {London}, year = {2009}, language = {en} } @inproceedings{TaylorKassiSchwarzkopfetal.2005, author = {Taylor, William R. and Kassi, J.-P. and Schwarzkopf, J. and Ehrig, Rainald and Schell, H. and Duda, G.}, title = {The Profile of Mechanical Loading is Independent of Fracture Fixation Principle}, series = {Proceedings of the 51th Annual Meeting of the Orthopedic Society}, booktitle = {Proceedings of the 51th Annual Meeting of the Orthopedic Society}, address = {Washington}, year = {2005}, language = {en} } @inproceedings{TaylorFroehlichButtgereitetal.2012, author = {Taylor, William R. and Fr{\"o}hlich, Annika and Buttgereit, Frank and Ehrig, Rainald and Witaschek, Tom and Duda, Georg}, title = {Metacarpophalangeal joint stiffness is reduced in patients affected by rheumatoid arthritis after glucocorticoid medication}, series = {Proceedings of the ESM-2012, Aalborg}, booktitle = {Proceedings of the ESM-2012, Aalborg}, editor = {Kersting, Uwe and Morlock, Michael and Jirova-Enzmann, Daniela and Dremstrup, Kim}, publisher = {Department of Health Science and Technology, Aalborg University}, pages = {39}, year = {2012}, language = {en} } @inproceedings{TaylorEhrigHelleretal.2005, author = {Taylor, William R. and Ehrig, Rainald and Heller, Markus O. and Schell, H. and Seebeck, P. and Duda, G.}, title = {Animal Models for Knee Injury Frequently Underestimate the Mechanical Conditions of the Clinical Situation}, series = {Proceedings of the 51th Annual Meeting of the Orthopedic Society}, booktitle = {Proceedings of the 51th Annual Meeting of the Orthopedic Society}, address = {Washington}, year = {2005}, language = {en} } @article{TaylorEhrigHelleretal.2006, author = {Taylor, William R. and Ehrig, Rainald and Heller, Markus O. and Schell, H. and Seebeck, P. and Duda, G.}, title = {Tibio-femoral Joint Contact Forces in Sheep}, series = {Journal of Biomechanics}, journal = {Journal of Biomechanics}, number = {39}, pages = {791 -- 798}, year = {2006}, language = {en} } @article{TaylorEhrigHelleretal.2005, author = {Taylor, William R. and Ehrig, Rainald and Heller, Markus O. and Schell, H. and Klein, P. and Duda, G.}, title = {On the Influence of Soft Tissue Coverage in the Determination of Bone Kinematics using Bone Markers}, series = {Journal of Orthopedic Research}, journal = {Journal of Orthopedic Research}, number = {23}, pages = {726 -- 734}, year = {2005}, language = {en} } @inproceedings{TaylorEhrigHelleretal.2004, author = {Taylor, William R. and Ehrig, Rainald and Heller, Markus O. and Schell, H. and Duda, G.}, title = {Can Skin Markers Determine the Kinematics of Underlying Bones?}, series = {Proceedings of the 50th Annual Meeting of the Orthopedic Society}, booktitle = {Proceedings of the 50th Annual Meeting of the Orthopedic Society}, address = {San Francisco}, year = {2004}, language = {en} } @inproceedings{TaylorEhrigDudaetal.2006, author = {Taylor, William R. and Ehrig, Rainald and Duda, G. and Heller, Markus O.}, title = {The determination of joint axes}, series = {5. World Congress of Biomechanics, Munich, Journal of Biomechanics}, booktitle = {5. World Congress of Biomechanics, Munich, Journal of Biomechanics}, number = {39, Suppl. 1}, pages = {S571 -- S572}, year = {2006}, language = {en} } @inproceedings{TaylorEhrigDudaetal.2006, author = {Taylor, William R. and Ehrig, Rainald and Duda, G. and Heller, Markus O.}, title = {The Symmetrical Axis of Rotation Approach (SARA) for Determination of Joint Axes in Clinical Gait Analysis}, series = {1st Joint ESMAC-GCMAS Meeting, Amsterdam}, booktitle = {1st Joint ESMAC-GCMAS Meeting, Amsterdam}, year = {2006}, language = {en} } @article{MoewisBoethHelleretal., author = {Moewis, Philippe and Boeth, Heide and Heller, Markus O. and Yntema, Caroline and Jung, Tobias and Doyscher, Ralf and Ehrig, Rainald and Zhong, Yanlin and Taylor, William R.}, title = {Towards understanding knee joint laxity: Errors in non-invasive assessment of joint rotation can be corrected}, series = {Medical Engineering and Physics}, volume = {36}, journal = {Medical Engineering and Physics}, number = {7}, doi = {doi.org/10.1016/j.medengphy.2014.03.017}, pages = {889 -- 895}, language = {en} } @inproceedings{KratzensteinTaylorEhrigetal.2009, author = {Kratzenstein, Stefan and Taylor, William R. and Ehrig, Rainald and Heller, Markus O.}, title = {Reduction of the influence of skin marker artefacts using the optimal common shape technique}, series = {Annual meeting of the ESMAC 2009}, booktitle = {Annual meeting of the ESMAC 2009}, address = {London}, year = {2009}, language = {en} } @article{KratzensteinKornaropoulosEhrigetal.2012, author = {Kratzenstein, Stefan and Kornaropoulos, Evgenios I. and Ehrig, Rainald and Heller, Markus O. and P{\"o}pplau, Berry M. and Taylor, William R.}, title = {Effective marker placement for functional identification of the centre of rotation at the hip}, series = {Gait \& Posture}, volume = {36}, journal = {Gait \& Posture}, number = {3}, doi = {http://dx.doi.org/10.1016/j.gaitpost.2012.04.011}, pages = {482 -- 486}, year = {2012}, language = {en} } @inproceedings{KratzensteinHellerEhrigetal.2010, author = {Kratzenstein, Stefan and Heller, Markus O. and Ehrig, Rainald and Wassilew, Georgi and Duda, Georg and Taylor, William R.}, title = {A new approach for optimally reducing skin marker artifact allows determination of the hip joint center within 3mm}, series = {Transactions Vol. 35, 2010 Annual Meeting of the Orthopedic Society}, booktitle = {Transactions Vol. 35, 2010 Annual Meeting of the Orthopedic Society}, address = {New Orleans}, year = {2010}, language = {en} }