Filters








6,748 Hits in 2.5 sec

Colour Constrained 4D Flow

T. C. Lukins, B. Fisher
2005 Procedings of the British Machine Vision Conference 2005  
This is applied in the form of additional optical flow constraints from aligned colour image data.  ...  The addition of colour information to the computation of range/scene flow is proposed to improve its accuracy and robustness to ambiguities.  ...  Calculating Colour Constrained 4D Flow Isolating Channels In our formulation we extend the original work of [10] which considers the varying depth of an orthographically captured surface (X,Y, Z) as  ... 
doi:10.5244/c.19.31 dblp:conf/bmvc/LukinsF05 fatcat:qpbnybd77rahhb2k3kzogv5igq

U4D: Unsupervised 4D Dynamic Scene Understanding

Armin Mustafa, Chris Russell, Adrian Hilton
2019 2019 IEEE/CVF International Conference on Computer Vision (ICCV)  
We further leverage recent advances in 3D pose estimation to constrain the joint semantic instance segmentation and 4D temporally coherent reconstruction.  ...  scene understanding framework against state-of-theart methods on challenging indoor and outdoor sequences demonstrates a significant (≈ 40%) improvement in semantic segmentation, reconstruction and scene flow  ...  The key-frames of sequence are coloured and the colour is propagated using dense flow from the joint optimisation throughout the sequence.  ... 
doi:10.1109/iccv.2019.01052 dblp:conf/iccv/Mustafa0H19 fatcat:gljhpdkiwrfrzpkg5cotp7nqva

4D Temporally Coherent Light-field Video [article]

Armin Mustafa, Marco Volino, Jean-yves Guillemaut, Adrian Hilton
2018 arXiv   pre-print
EPIs are used to constrain scene flow estimation to obtain 4D temporally coherent representations of dynamic light-fields. Temporal coherence is achieved on a variety of light-field datasets.  ...  Evaluation of the proposed light-field scene flow against existing multi-view dense correspondence approaches demonstrates a significant improvement in accuracy of temporal coherence.  ...  EPI is used to obtain dense scene flow for 4D temporally coherent rep-resentation of dynamic light-field video to enable compression and efficient light-field video editing (colour grading, object removal  ... 
arXiv:1804.11276v1 fatcat:ddlq52jhdfao3fxwu3xmfr5ccq

4D Temporally Coherent Light-Field Video

Armin Mustafa, Marco Volino, Jean-Yves Guillemaut, Adrian Hilton
2017 2017 International Conference on 3D Vision (3DV)  
EPIs are used to constrain scene flow estimation to obtain 4D temporally coherent representations of dynamic light-fields. Temporal coherence is achieved on a variety of light-field datasets.  ...  Evaluation of the proposed light-field scene flow against existing multiview dense correspondence approaches demonstrates a significant improvement in accuracy of temporal coherence.  ...  EPI is used to obtain dense scene flow for 4D temporally coherent rep-resentation of dynamic light-field video to enable compression and efficient light-field video editing (colour grading, object removal  ... 
doi:10.1109/3dv.2017.00014 dblp:conf/3dim/MustafaVGH17 fatcat:agntgnv5d5gafnjey54gqivnja

4D Blood Flow Reconstruction Over the Entire Ventricle From Wall Motion and Blood Velocity Derived From Ultrasound Data

Alberto Gomez, Adelaide de Vecchi, Martin Jantsch, Wenzhe Shi, Kuberan Pushparajah, John M. Simpson, Nicolas P. Smith, Daniel Rueckert, Tobias Schaeffter, Graeme P. Penney
2015 IEEE Transactions on Medical Imaging  
We demonstrate a new method to recover 4D blood flow over the entire ventricle from partial blood velocity measurements using multiple 3D+t colour Doppler images and ventricular wall motion estimated using  ...  The use of wall motion produced more plausible flow patterns and reduced the reconstruction error in all patients.  ...  Time resolved, 3D cardiac blood velocity can be currently imaged using phase-contrast magnetic resonance imaging (4D flow MRI) and echocardiographic particle image velocimetry (echo-PIV). 4D flow MRI remains  ... 
doi:10.1109/tmi.2015.2428932 pmid:25955584 pmcid:PMC7115944 fatcat:o7p6qc2oebeq3epnrbwj2enesm

Optical Flow on Evolving Surfaces with an Application to the Analysis of 4D Microscopy Data [chapter]

Clemens Kirisits, Lukas F. Lang, Otmar Scherzer
2013 Lecture Notes in Computer Science  
We extend the concept of optical flow to a dynamic non-Euclidean setting. Optical flow is traditionally computed from a sequence of flat images.  ...  For demonstration purpose we make use of the standard flow colour-coding [1] , which maps (normalised) flow vectors to a colour space defined inside the unit circle.  ...  This means that (4) constrains the motion relative to the tangential surface velocity ẋtan , while (6) constrains the absolute tangential motion.  ... 
doi:10.1007/978-3-642-38267-3_21 fatcat:ffzilq47bnhixf23fy4hci4j3q

Temporally Coherent 4D Reconstruction of Complex Dynamic Scenes

Armin Mustafa, Hansung Kim, Jean-Yves Guillemaut, Adrian Hilton
2016 2016 IEEE Conference on Computer Vision and Pattern Recognition (CVPR)  
This paper presents an approach for reconstruction of 4D temporally coherent models of complex dynamic scenes.  ...  This demonstrates reconstruction of complete temporally coherent 4D scene models with improved nonrigid object segmentation and shape reconstruction.  ...  Sparse 3D feature correspondences are used to constrain optical flow estimation to obtain an initial dense temporally consistent model of dynamic regions.  ... 
doi:10.1109/cvpr.2016.504 dblp:conf/cvpr/MustafaKGH16 fatcat:5iz2zxxs35hudkwnqo5hoftf3a

Comparing different approaches of time-lapse seismic inversion

Daiane R Rosa, Juliana M C Santos, Rafael M Souza, Dario Grana, Denis J Schiozer, Alessandra Davolio, Yanghua Wang
2020 Journal of Geophysics and Engineering  
We compare the standard deterministic methods, such as coloured and model-based inversions, and the probabilistic inversion techniques based on a Bayesian approach.  ...  Possible approaches for 4D seismic inversion include two classes of method: sequential independent 3D inversions and joint inversion of 4D seismic differences.  ...  Acknowledgements This work was carried out in association with the ongoing Project (grant no. 20372-9 ANP) 'Development of integration between reservoir simulation and seismic 4D -Phase 2'  ... 
doi:10.1093/jge/gxaa053 fatcat:n4pwgo5ib5edzczhtb5ek4gyq4

Temporally coherent 4D reconstruction of complex dynamic scenes [article]

Armin Mustafa, Hansung Kim, Jean-Yves Guillemaut, Adrian Hilton
2016 arXiv   pre-print
This paper presents an approach for reconstruction of 4D temporally coherent models of complex dynamic scenes.  ...  This demonstrates reconstruction of complete temporally coherent 4D scene models with improved nonrigid object segmentation and shape reconstruction.  ...  Sparse 3D feature process each time frame independently due to the difficulty correspondences are used to constrain optical flow estima- of  ... 
arXiv:1603.03381v2 fatcat:hvo5vh55arbz3iaqrij7fvvslu

4D Match Trees for Non-rigid Surface Alignment [chapter]

Armin Mustafa, Hansung Kim, Adrian Hilton
2016 Lecture Notes in Computer Science  
Dense 4D temporal correspondence across all frames is then estimated by traversing the 4D Match tree using optical flow initialised from the sparse feature matches.  ...  Comparison to previous 2D and 3D scene flow demonstrates that 4D Match Trees achieve reduced errors due to drift and improved robustness to large non-rigid deformations.  ...  Dense 4D temporal correspondence is estimated from the 4D Match tree across all frames using guided optical flow.  ... 
doi:10.1007/978-3-319-46448-0_13 fatcat:qngtp7nq6jblpcrkvopc3irixi

Semantically Coherent 4D Scene Flow of Dynamic Scenes

Armin Mustafa, Adrian Hilton
2019 International Journal of Computer Vision  
Semantic coherence results in improved 4D scene flow estimation, segmentation and reconstruction for complex dynamic scenes.  ...  Semantic tracklets are introduced to robustly initialize the scene flow in the joint estimation and enforce temporal coherence in 4D flow, semantic labelling and reconstruction between widely spaced instances  ...  This provides a prior to constrain longterm flow, co-segmentation and reconstruction.  ... 
doi:10.1007/s11263-019-01241-w fatcat:czf3b4zytvf4zn5wexeya4quo4

4D synchrotron X-ray tomographic quantification of the transition from cellular to dendrite growth during directional solidification

B. Cai, J. Wang, A. Kao, K. Pericleous, A.B. Phillion, R.C. Atwood, P.D. Lee
2016 Acta Materialia  
The results demonstrate that 4D imaging can provide new data to both inform and validate solidification models.  ...  In this study, we performed 4D synchrotron X-ray tomographic imaging (three spatial directions plus time), to study the transition from cellular to a columnar dendritic morphology and the subsequent growth  ...  , suggesting no convective flows, just buoyancy is operative.  ... 
doi:10.1016/j.actamat.2016.07.002 fatcat:mtbjkbihojhx7gljz5tdkw6ssa

Space-Time Joint Multi-layer Segmentation and Depth Estimation

Jean-Yves Guillemaut, Adrian Hilton
2012 2012 Second International Conference on 3D Imaging, Modeling, Processing, Visualization & Transmission  
The main idea is to use optical flow in combination with a confidence measure to impose robust temporal smoothness constraints.  ...  containing rapid motion demonstrate that the method is able to improve spatio-temporal coherence both in terms of segmentation and reconstruction without introducing any degradation in regions where optical flow  ...  Results demonstrate that the method is able to reduce noise on surfaces where optical flow correspondences can be reliably inferred without resulting in a reduction in quality in less constrained areas  ... 
doi:10.1109/3dimpvt.2012.44 dblp:conf/3dim/GuillemautH12 fatcat:vnooxdqrrreutaogx56uljn6te

Impact of prosthetic mitral valve orientation on the ventricular flow field: comparison using patient-specific Computational Fluid Dynamics

Jonas Lantz, Sophia Bäck, Carl-Johan Carlhäll, Ann Bolger, Anders Persson, Matts Karlsson, Tino Ebbers
2020 Journal of Biomechanics  
Results were validated using in vivo 4D Flow MRI.  ...  Flow patterns were visualized in long- and short-axes and quantified with flow component analysis.  ...  (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)  ... 
doi:10.1016/j.jbiomech.2020.110209 pmid:33422725 fatcat:auksl2cdlbbrzix53x3lvfsawy

The glacial geomorphology of western Dronning Maud Land, Antarctica

J. C. H. Newall, T. Dymova, E. Serra, R. Blomdin, O. Fredin, N. F. Glasser, Y. Suganuma, J. M. Harbor, A. P. Stroeven
2020 Journal of Maps  
Ten landform categories have been mapped, and the landform distributions provide evidence constraining spatial patterns of a previously thicker ice sheet. ARTICLE HISTORY  ...  Reconstructing the response of present-day ice sheets to past global climate change is important for constraining and refining the numerical models which forecast future contributions of these ice sheets  ...  Where there was a distinct ridge or structure within the supraglacial debris this was mapped as a line feature supraglacial debris structure (Figure 4d ).  ... 
doi:10.1080/17445647.2020.1761464 fatcat:pqocsal5ybaehgcaqrawigy6l4
« Previous Showing results 1 — 15 out of 6,748 results