32-Issue 2

Permanent URI for this collection

https://diglib.eg.org/handle/10.2312/180
EG Proceedings

BibTeX (32-Issue 2)
                
@article{
https::/diglib.eg.org/handle/10.1111/000_preface_eg2013.pdf,

journal = {Computer Graphics Forum},
title = {{
Preface and Table of Contents}},

author = {},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
https://diglib.eg.org/handle/10.1111/000_preface_eg2013.pdf}

}
                
@article{
10.1111:cgf.12020,

journal = {Computer Graphics Forum},
title = {{
Circular Arc Snakes and Kinematic Surface Generation}},

author = {
Barton, Michael
 and 
Shi, Ling
 and 
Kilian, Martin
 and 
Wallner, Johannes
 and 
Pottmann, Helmut
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12020}

}
                
@article{
10.1111:cgf.12021,

journal = {Computer Graphics Forum},
title = {{
Exploring Local Modifications for Constrained Meshes}},

author = {
Deng, Bailin
 and 
Bouaziz, Sofien
 and 
Deuss, Mario
 and 
Zhang, Juyong
 and 
Schwartzburg, Yuliy
 and 
Pauly, Mark
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12021}

}
                
@article{
10.1111:cgf.12022,

journal = {Computer Graphics Forum},
title = {{
Mutable Elastic Models for Sculpting Structured Shapes}},

author = {
Milliez, Antoine
 and 
Wand, Michael
 and 
Cani, Marie-Paule
 and 
Seidel, Hans-Peter
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12022}

}
                
@article{
10.1111:cgf.12023,

journal = {Computer Graphics Forum},
title = {{
Finite Element Image Warping}},

author = {
Kaufmann, Peter
 and 
Wang, Oliver
 and 
Sorkine-Hornung, Alexander
 and 
Sorkine-Hornung, Olga
 and 
Smolic, Aljoscha
 and 
Gross, Markus
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12023}

}
                
@article{
10.1111:cgf.12025,

journal = {Computer Graphics Forum},
title = {{
DuctTake: Spatiotemporal Video Compositing}},

author = {
Rüegg, Jan
 and 
Wang, Oliver
 and 
Smolic, Aljoscha
 and 
Gross, Markus
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12025}

}
                
@article{
10.1111:cgf.12026,

journal = {Computer Graphics Forum},
title = {{
Path Space Regularization for Holistic and Robust Light Transport}},

author = {
Kaplanyan, Anton S.
 and 
Dachsbacher, Carsten
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12026}

}
                
@article{
10.1111:cgf.12024,

journal = {Computer Graphics Forum},
title = {{
Accurate Binary Image Selection from Inaccurate User Input}},

author = {
Subr, Kartic
 and 
Paris, Sylvain
 and 
Soler, Cyril
 and 
Kautz, Jan
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12024}

}
                
@article{
10.1111:cgf.12027,

journal = {Computer Graphics Forum},
title = {{
Locally Adaptive Products for All-Frequency Relighting}},

author = {
Inger, Yaron
 and 
Farbman, Zeev
 and 
Lischinski, Dani
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12027}

}
                
@article{
10.1111:cgf.12028,

journal = {Computer Graphics Forum},
title = {{
Photon Parameterisation for Robust Relaxation Constraints}},

author = {
Spencer, Ben
 and 
Jones, Mark W.
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12028}

}
                
@article{
10.1111:cgf.12029,

journal = {Computer Graphics Forum},
title = {{
Removing the Noise in Monte Carlo Rendering with General Image Denoising Algorithms}},

author = {
Kalantari, Nima Khademi
 and 
Sen, Pradeep
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12029}

}
                
@article{
10.1111:cgf.12030,

journal = {Computer Graphics Forum},
title = {{
Stochastic Depth Buffer Compression using Generalized Plane Encoding}},

author = {
Andersson, Magnus
 and 
Munkberg, Jacob
 and 
Akenine-Möller, Tomas
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12030}

}
                
@article{
10.1111:cgf.12031,

journal = {Computer Graphics Forum},
title = {{
Global Selection of Stream Surfaces}},

author = {
Esturo, Janick Martinez
 and 
Schulze, Maik
 and 
Rössl, Christian
 and 
Theisel, Holger
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12031}

}
                
@article{
10.1111:cgf.12032,

journal = {Computer Graphics Forum},
title = {{
Bilateral Hermite Radial Basis Functions for Contour-based Volume Segmentation}},

author = {
Ijiri, Takashi
 and 
Yoshizawa, Shin
 and 
Sato, Yu
 and 
Ito, Masaaki
 and 
Yokota, Hideo
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12032}

}
                
@article{
10.1111:cgf.12033,

journal = {Computer Graphics Forum},
title = {{
Physics Storyboards}},

author = {
Ha, Sehoon
 and 
McCann, Jim
 and 
Liu, C. Karen
 and 
Popovic, Jovan
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12033}

}
                
@article{
10.1111:cgf.12034,

journal = {Computer Graphics Forum},
title = {{
Stylized and Performative Gaze for Character Animation}},

author = {
Pejsa, Tomislav
 and 
Mutlu, Bilge
 and 
Gleicher, Michael
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12034}

}
                
@article{
10.1111:cgf.12035,

journal = {Computer Graphics Forum},
title = {{
Animal Locomotion Controllers From Scratch}},

author = {
Wampler, Kevin
 and 
Popovic, Jovan
 and 
Popovic,  Zoran
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12035}

}
                
@article{
10.1111:cgf.12036,

journal = {Computer Graphics Forum},
title = {{
Gaze-driven Object Tracking for Real Time Rendering}},

author = {
Mantiuk, Radoslaw
 and 
Bazyluk, Bartosz
 and 
Mantiuk, Rafal K.
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12036}

}
                
@article{
10.1111:cgf.12037,

journal = {Computer Graphics Forum},
title = {{
Freeform Shadow Boundary Editing}},

author = {
Mattausch, Oliver
 and 
Igarashi, Takeo
 and 
Wimmer, Michael
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12037}

}
                
@article{
10.1111:cgf.12038,

journal = {Computer Graphics Forum},
title = {{
Material Editing in Complex Scenes by Surface Light Field Manipulation and Reflectance Optimization}},

author = {
Nguyen, Chuong H.
 and 
Scherzer, Daniel
 and 
Ritschel, Tobias
 and 
Seidel, Hans-Peter
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12038}

}
                
@article{
10.1111:cgf.12040,

journal = {Computer Graphics Forum},
title = {{
A Correlated Parts Model for Object Detection in Large 3D Scans}},

author = {
Sunkel, Martin
 and 
Jansen,  Silke
 and 
Wand, Michael
 and 
Seidel, Hans-Peter
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12040}

}
                
@article{
10.1111:cgf.12041,

journal = {Computer Graphics Forum},
title = {{
Interactive Facades - Analysis and Synthesis of Semi-Regular Facades}},

author = {
AlHalawani, Sawsan
 and 
Yang, Yong-Liang
 and 
Liu, Han
 and 
Mitra, Niloy J.
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12041}

}
                
@article{
10.1111:cgf.12039,

journal = {Computer Graphics Forum},
title = {{
Smart Variations: Functional Substructures for Part Compatibility}},

author = {
Zheng, Youyi
 and 
Cohen-Or, Daniel
 and 
Mitra, Niloy J.
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12039}

}
                
@article{
10.1111:cgf.12042,

journal = {Computer Graphics Forum},
title = {{
Surface Reconstruction through Point Set Structuring}},

author = {
Lafarge, Florent
 and 
Alliez, Pierre
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12042}

}
                
@article{
10.1111:cgf.12043,

journal = {Computer Graphics Forum},
title = {{
ArtiSketch: A System for Articulated Sketch Modeling}},

author = {
Levi, Zohar
 and 
Gotsman, Craig
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12043}

}
                
@article{
10.1111:cgf.12044,

journal = {Computer Graphics Forum},
title = {{
Geosemantic Snapping for Sketch-Based Modeling}},

author = {
Shtof, Alex
 and 
Agathos, Alexander
 and 
Gingold, Yotam
 and 
Shamir, Ariel
 and 
Cohen-Or, Daniel
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12044}

}
                
@article{
10.1111:cgf.12045,

journal = {Computer Graphics Forum},
title = {{
Stroke Parameterization}},

author = {
Schmidt, Ryan
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12045}

}
                
@article{
10.1111:cgf.12046,

journal = {Computer Graphics Forum},
title = {{
Pose Space Image Based Rendering}},

author = {
Hilsmann, Anna
 and 
Fechteler, Philipp
 and 
Eisert, Peter
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12046}

}
                
@article{
10.1111:cgf.12047,

journal = {Computer Graphics Forum},
title = {{
Capturing Relightable Human Performances under General Uncontrolled Illumination}},

author = {
Li, Guannan
 and 
Wu, Chenglei
 and 
Stoll, Carsten
 and 
Liu, Yebin
 and 
Varanasi, Kiran
 and 
Dai, Qionghai
 and 
Theobalt, Christian
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12047}

}
                
@article{
10.1111:cgf.12048,

journal = {Computer Graphics Forum},
title = {{
Capture and Statistical Modeling of Arm-Muscle Deformations}},

author = {
Neumann, Thomas
 and 
Varanasi, Kiran
 and 
Hasler, Nils
 and 
Wacker, Markus
 and 
Magnor, Marcus
 and 
Theobalt, Christian
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12048}

}
                
@article{
10.1111:cgf.12049,

journal = {Computer Graphics Forum},
title = {{
Fleshing: Spine-driven Bending with Local Volume Preservation}},

author = {
Zhuo, Wei
 and 
Rossignac, Jarek
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12049}

}
                
@article{
10.1111:cgf.12050,

journal = {Computer Graphics Forum},
title = {{
Computing and Fabricating Multiplanar Models}},

author = {
Chen, Desai
 and 
Sitthi-amorn, Pitchaya
 and 
Lan, Justin T.
 and 
Matusik, Wojciech
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12050}

}
                
@article{
10.1111:cgf.12052,

journal = {Computer Graphics Forum},
title = {{
Interactive Exploration and Flattening of Deformed Historical Documents}},

author = {
Pal, Kazim
 and 
Terras, Melissa
 and 
Weyrich, Tim
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12052}

}
                
@article{
10.1111:cgf.12051,

journal = {Computer Graphics Forum},
title = {{
Fabrication-aware Design with Intersecting Planar Pieces}},

author = {
Schwartzburg, Yuliy
 and 
Pauly, Mark
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12051}

}
                
@article{
10.1111:cgf.12053,

journal = {Computer Graphics Forum},
title = {{
Measurement-Based Synthesis of Facial Microgeometry}},

author = {
Graham, Paul
 and 
Tunwattanapong, Borom
 and 
Busch, Jay
 and 
Yu, Xueming
 and 
Jones, Andrew
 and 
Debevec, Paul
 and 
Ghosh, Abhijeet
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12053}

}
                
@article{
10.1111:cgf.12054,

journal = {Computer Graphics Forum},
title = {{
Scalable Music: Automatic Music Retargeting and Synthesis}},

author = {
Wenner, Simon
 and 
Bazin, Jean-Charles
 and 
Sorkine-Hornung, Alexander
 and 
Kim, Changil
 and 
Gross, Markus
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12054}

}
                
@article{
10.1111:cgf.12055,

journal = {Computer Graphics Forum},
title = {{
By-example Synthesis of Curvilinear Structured Patterns}},

author = {
Zhou, Shizhe
 and 
Lasram, Anass
 and 
Lefebvre, Sylvain
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12055}

}
                
@article{
10.1111:cgf.12057,

journal = {Computer Graphics Forum},
title = {{
A Particle-Grid Method for Opaque Ice Formation}},

author = {
Im, Jaeho
 and 
Park, Hanwook
 and 
Kim, Jong-Hyun
 and 
Kim, Chang-Hun
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12057}

}
                
@article{
10.1111:cgf.12056,

journal = {Computer Graphics Forum},
title = {{
Example-based Interpolation and Synthesis of Bidirectional Texture Functions}},

author = {
Ruiters, Roland
 and 
Schwartz, Christopher
 and 
Klein, Reinhard
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12056}

}
                
@article{
10.1111:cgf.12058,

journal = {Computer Graphics Forum},
title = {{
Geometry-Aware Volume-of-Fluid Method}},

author = {
Cho, Junghyun
 and 
Ko, Hyeong-Seok
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12058}

}
                
@article{
10.1111:cgf.12059,

journal = {Computer Graphics Forum},
title = {{
A Novel Projection Technique with Detail Capture and Shape Correction for Smoke Simulation}},

author = {
Wu, Xiaoyue
 and 
Yang, Xubo
 and 
Yang, Yang
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12059}

}
                
@article{
10.1111:cgf.12060,

journal = {Computer Graphics Forum},
title = {{
Adaptive Quantization Visibility Caching}},

author = {
Popov, Stefan
 and 
Georgiev, Iliyan
 and 
Slusallek, Philipp
 and 
Dachsbacher, Carsten
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12060}

}
                
@article{
10.1111:cgf.12061,

journal = {Computer Graphics Forum},
title = {{
Analytic Visibility on the GPU}},

author = {
Auzinger, Thomas
 and 
Wimmer, Michael
 and 
Jeschke, Stefan
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12061}

}
                
@article{
10.1111:cgf.12062,

journal = {Computer Graphics Forum},
title = {{
Primitive Trees for Precomputed Distance Queries}},

author = {
Lee, Sung-Ho
 and 
Park, Taejung
 and 
Kim, Chang-Hun
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12062}

}
                
@article{
10.1111:cgf.12063,

journal = {Computer Graphics Forum},
title = {{
Landmark-Guided Elastic Shape Analysis of Spherically-Parameterized Surfaces}},

author = {
Kurtek, Sebastian
 and 
Srivastava, Anuj
 and 
Klassen, Eric
 and 
Laga, Hamid
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12063}

}
                
@article{
10.1111:cgf.12064,

journal = {Computer Graphics Forum},
title = {{
Coupled Quasi-harmonic Bases}},

author = {
Kovnatsky, Artiom
 and 
Bronstein, Michael M.
 and 
Bronstein, Alexander M.
 and 
Glashoff, Klaus
 and 
Kimmel, Ron
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12064}

}
                
@article{
10.1111:cgf.12066,

journal = {Computer Graphics Forum},
title = {{
Sparse Modeling of Intrinsic Correspondences}},

author = {
Pokrass, Jonathan
 and 
Bronstein, Alexander M.
 and 
Bronstein, Michael M.
 and 
Sprechmann, Pablo
 and 
Sapiro, Guillermo
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12066}

}
                
@article{
10.1111:cgf.12065,

journal = {Computer Graphics Forum},
title = {{
A Data-Driven Approach to Realistic Shape Morphing}},

author = {
Gao, Lin
 and 
Lai, Yu-Kun
 and 
Huang, Qi-Xing
 and 
Hu, Shi-Min
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12065}

}
                
@article{
10.1111:cgf.12067,

journal = {Computer Graphics Forum},
title = {{
Rendering Gigaray Light Fields}},

author = {
Birklbauer, Clemens
 and 
Opelt,  Simon
 and 
Bimber, Oliver
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12067}

}
                
@article{
10.1111:cgf.12068,

journal = {Computer Graphics Forum},
title = {{
View-Dependent Realtime Rendering of Procedural Facades with High Geometric Detail}},

author = {
Krecklau, Lars
 and 
Born, Janis
 and 
Kobbelt, Leif
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12068}

}
                
@article{
10.1111:cgf.12069,

journal = {Computer Graphics Forum},
title = {{
Sharpening Out of Focus Images using High-Frequency Transfer}},

author = {
Tao, Michael W.
 and 
Malik, Jitendra
 and 
Ramamoorthi, Ravi
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12069}

}
                
@article{
10.1111:cgf.12070,

journal = {Computer Graphics Forum},
title = {{
Analytic Rasterization of Curves with Polynomial Filters}},

author = {
Manson, Josiah
 and 
Schaefer, Scott
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12070}

}
                
@article{
10.1111:cgf.12071,

journal = {Computer Graphics Forum},
title = {{
Sifted Disks}},

author = {
Ebeida, Mohamed S.
 and 
Mahmoud, Ahmed H.
 and 
Awad, Muhammad A.
 and 
Mohammed, Mohammed A.
 and 
Mitchell, Scott A.
 and 
Rand, Alexander
 and 
Owens, John D.
},
year = {
2013},

publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},


ISSN = {1467-8659},

DOI = {
10.1111/cgf.12071}

}

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    Preface and Table of Contents
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) I. Navazo, P. Poulin
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    Circular Arc Snakes and Kinematic Surface Generation
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Barton, Michael; Shi, Ling; Kilian, Martin; Wallner, Johannes; Pottmann, Helmut; I. Navazo, P. Poulin
    We discuss the theory, discretization, and numerics of curves which are evolving such that part of their shape, or at least their curvature as a function of arc length, remains unchanged. The discretization of a curve as a smooth sequence of circular arcs is well suited for such purposes, and allows us to reduce evolution of curves to the evolution of a control point collection in a certain finite-dimensional shape space. We approach this evolution by a 2-step process: linearized evolution via optimized velocity fields, followed by optimization in order to exactly fulfill all geometric side conditions. We give applications to freeform architecture, including ''rationalization'' of a surface by congruent arcs, form finding and, most interestingly, non-static architecture.
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    Exploring Local Modifications for Constrained Meshes
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Deng, Bailin; Bouaziz, Sofien; Deuss, Mario; Zhang, Juyong; Schwartzburg, Yuliy; Pauly, Mark; I. Navazo, P. Poulin
    Mesh editing under constraints is a challenging task with numerous applications in geometric modeling, industrial design, and architectural form finding. Recent methods support constraint-based exploration of meshes with fixed connectivity, but commonly lack local control. Because constraints are often globally coupled, a local modification by the user can have global effects on the surface, making iterative design exploration and refinement difficult. Simply fixing a local region of interest a priori is problematic, as it is not clear in advance which parts of the mesh need to be modified to obtain an aesthetically pleasing solution that satisfies all constraints. We propose a novel framework for exploring local modifications of constrained meshes. Our solution consists of three steps. First, a user specifies target positions for one or more vertices. Our algorithm computes a sparse set of displacement vectors that satisfies the constraints and yields a smooth deformation. Then we build a linear subspace to allow realtime exploration of local variations that satisfy the constraints approximately. Finally, after interactive exploration, the result is optimized to fully satisfy the set of constraints. We evaluate our framework on meshes where each face is constrained to be planar.
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    Mutable Elastic Models for Sculpting Structured Shapes
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Milliez, Antoine; Wand, Michael; Cani, Marie-Paule; Seidel, Hans-Peter; I. Navazo, P. Poulin
    In this paper, we propose a new paradigm for free-form shape deformation. Standard deformable models minimize an energy measuring the distance to a single target shape. We propose a new, ''mutable'' elastic model. It represents complex geometry by a collection of parts and measures the distance of each part measures to a larger set of alternative rest configurations. By detecting and reacting to local switches between best-matching rest states, we build a 3D sculpting system: It takes a structured shape consisting of parts and replacement rules as input. The shape can subsequently be elongated, compressed, bent, cut, and merged within a constraints-based free-form editing interface, where alternative rest-states model to such changes. In practical experiments, we show that the approach yields a surprisingly intuitive and easy to implement interface for interactively designing objects described by such discrete shape grammars, for which direct shape control mechanisms were typically lacking.
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    Finite Element Image Warping
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Kaufmann, Peter; Wang, Oliver; Sorkine-Hornung, Alexander; Sorkine-Hornung, Olga; Smolic, Aljoscha; Gross, Markus; I. Navazo, P. Poulin
    We introduce a single unifying framework for a wide range of content-aware image warping tasks using a finite element method (FEM). Existing approaches commonly define error terms over vertex finite differences and can be expressed as a special case of our general FEM model. In this work, we exploit the full generality of FEMs, gaining important advantages over prior methods. These advantages include arbitrary mesh connectivity allowing for adaptive meshing and efficient large-scale solutions, a well-defined continuous problem formulation that enables clear analysis of existing warping error functions and allows us to propose improved ones, and higher order basis functions that allow for smoother warps with fewer degrees of freedom. To support per-element basis functions of varying degree and complex mesh connectivity with hanging nodes, we also introduce a novel use of discontinuous Galerkin FEM. We demonstrate the utility of our method by showing examples in video retargeting and camera stabilization applications, and compare our results with previous state of the art methods.
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    DuctTake: Spatiotemporal Video Compositing
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Rüegg, Jan; Wang, Oliver; Smolic, Aljoscha; Gross, Markus; I. Navazo, P. Poulin
    DuctTake is a system designed to enable practical compositing of multiple takes of a scene into a single video. Current industry solutions are based around object segmentation, a hard problem that requires extensive manual input and cleanup, making compositing an expensive part of the film-making process. Our method instead composites shots together by finding optimal spatiotemporal seams using motion-compensated 3D graph cuts through the video volume. We describe in detail the required components, decisions, and new techniques that together make a usable, interactive tool for compositing HD video, paying special attention to running time and performance of each section. We validate our approach by presenting a wide variety of examples and by comparing result quality and creation time to composites made by professional artists using current state-of-the-art tools.
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    Path Space Regularization for Holistic and Robust Light Transport
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Kaplanyan, Anton S.; Dachsbacher, Carsten; I. Navazo, P. Poulin
    We propose a simple yet powerful regularization framework for robust light transport simulation. It builds on top of existing unbiased methods and resorts to a consistent estimation using regularization only for paths which cannot be sampled in an unbiased way. To introduce as little bias as possible, we selectively regularize individual interactions along paths, and also derive the regularization consistency conditions. Our approach is compatible with the majority of unbiased methods, e.g. (bidirectional) path tracing and Metropolis light transport (MLT), and only a simple modification is required to adapt existing renderers. We compare to recent unbiased and consistent methods and show examples of scenes with difficult light paths, where regularization is required to account for all illumination features. When coupled with MLT we are able to sample all phenomena, like recent consistent methods, while achieving superior convergence.
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    Accurate Binary Image Selection from Inaccurate User Input
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Subr, Kartic; Paris, Sylvain; Soler, Cyril; Kautz, Jan; I. Navazo, P. Poulin
    Selections are central to image editing, e.g., they are the starting point of common operations such as copy-pasting and local edits. Creating them by hand is particularly tedious and scribble-based techniques have been introduced to assist the process. By interpolating a few strokes specified by users, these methods generate precise selections. However, most of the algorithms assume a 100 percent accurate input, and even small inaccuracies in the scribbles often degrade the selection quality, which imposes an additional burden on users. In this paper, we propose a selection technique tolerant to input inaccuracies. We use a dense conditional random field (CRF) to robustly infer a selection from possibly inaccurate input. Further, we show that patch-based pixel similarity functions yield more precise selection than simple point-wise metrics. However, efficiently solving a dense CRF is only possible in low-dimensional Euclidean spaces, and the metrics that we use are high-dimensional and often non-Euclidean.We address this challenge by embedding pixels in a low-dimensional Euclidean space with a metric that approximates the desired similarity function. The results show that our approach performs better than previous techniques and that two options are sufficient to cover a variety of images depending on whether the objects are textured.
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    Locally Adaptive Products for All-Frequency Relighting
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Inger, Yaron; Farbman, Zeev; Lischinski, Dani; I. Navazo, P. Poulin
    Triple product integrals evaluate the shading at a point by factoring the reflection equation into incident illumination, visibility, and BRDF. By densely sampling the space of incident directions, this approach is capable of highly accurate rendering scenes lit by high-frequency environment lighting, containing complex materials and featuring intricate shadows. Efficient evaluation of triple product integrals using Haar wavelets enables near-interactive rendering of such scenes, while dynamically changing the lighting and the view. Although faster methods have been proposed in the recent real-time rendering literature, the approximations employed in these methods typically limit them to lower frequency phenomena. In this paper, we present a new approach for high-frequency scene relighting within the triple product framework. Our approach breaks the computation to smaller solid angles (blocks) over most of which the triple product degenerates to a dot product. We introduce a lossless, yet compact, differential representation of the visibility function over each block, and sample the BRDF on the fly, eliminating the need to store multiple rotated copies of each BRDF. By combining these ideas, we are able to achieve true interactive performance even when running on a CPU, while supporting high frequency effects in scenes with high vertex counts.
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    Photon Parameterisation for Robust Relaxation Constraints
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Spencer, Ben; Jones, Mark W.; I. Navazo, P. Poulin
    This paper presents a novel approach to detecting and preserving fine illumination structure within photon maps. Data derived from each photon's primal trajectory is encoded and used to build a high-dimensional kd-tree. Incorporation of these new parameters allows for precise differentiation between intersecting ray envelopes, thus minimizing detail degradation when combined with photon relaxation. We demonstrate how parameter-aware querying is beneficial in both detecting and removing noise. We also propose a more robust structure descriptor based on principal components analysis that better identifies anisotropic detail at the sub-kernel level.We illustrate the effectiveness of our approach in several example scenes and show significant improvements when rendering complex caustics compared to previous methods.
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    Removing the Noise in Monte Carlo Rendering with General Image Denoising Algorithms
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Kalantari, Nima Khademi; Sen, Pradeep; I. Navazo, P. Poulin
    Monte Carlo rendering systems can produce important visual effects such as depth of field, motion blur, and area lighting, but the rendered images suffer from objectionable noise at low sampling rates. Although years of research in image processing has produced powerful denoising algorithms, most of them assume that the noise is spatially-invariant over the entire image and cannot be directly applied to denoise Monte Carlo rendering. In this paper, we propose a new approach that enables the use of any spatially-invariant image denoising technique to remove the noise in Monte Carlo renderings. Our key insight is to use a noise estimation metric to locally identify the amount of noise in different parts of the image, coupled with a multilevel algorithm that denoises the image in a spatially-varying manner using a standard denoising technique. We also propose a new way to perform adaptive sampling that uses the noise estimation metric to identify the noisy regions in which to place more samples. We show that our framework runs in a few seconds with modern denoising algorithms and produces results that outperform state-of-the-art techniques in Monte Carlo rendering.
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    Stochastic Depth Buffer Compression using Generalized Plane Encoding
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Andersson, Magnus; Munkberg, Jacob; Akenine-Möller, Tomas; I. Navazo, P. Poulin
    In this paper, we derive compact representations of the depth function for a triangle undergoing motion or defocus blur. Unlike a static primitive, where the depth function is planar, the depth function is a rational function in time and the lens parameters. Furthermore, we show how these compact depth functions can be used to design an efficient depth buffer compressor/decompressor, which significantly lowers total depth buffer bandwidth usage for a range of test scenes. In addition, our compressor/decompressor is simpler in the number of operations needed to execute, which makes our algorithm more amenable for hardware implementation than previous methods
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    Global Selection of Stream Surfaces
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Esturo, Janick Martinez; Schulze, Maik; Rössl, Christian; Theisel, Holger; I. Navazo, P. Poulin
    Stream surfaces are well-known and widely-used structures for 3D flow visualization. A single surface can be sufficient to represent important global flow characteristics. Unfortunately, due to the huge space of possible stream surfaces, finding the globally most representative stream surface turns out to be a hard task that is usually performed by time-consuming manual trial and error exploration using slight modifications of seed geometries. To assist users we propose a new stream surface selection method that acts as an automatic preprocessing step before data analysis. We measure stream surface relevance by a novel surface-based quality measure that prefers surfaces where the flow is aligned with principal curvature directions. The problem of seed structure selection can then be reduced to the computation of simple minimal paths in a weighted graph spanning the domain. We apply a simulated annealing-based optimization method to find smooth seed curves of globally near-optimal stream surfaces. We illustrate the effectiveness of our method on a series of synthetic and real-world data sets.
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    Bilateral Hermite Radial Basis Functions for Contour-based Volume Segmentation
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Ijiri, Takashi; Yoshizawa, Shin; Sato, Yu; Ito, Masaaki; Yokota, Hideo; I. Navazo, P. Poulin
    In this paper, we propose a novel contour-based volume image segmentation technique. Our technique is based on an implicit surface reconstruction strategy, whereby a signed scalar field is generated from user-specified contours. The key idea is to compute the scalar field in a joint spatial-range domain (i.e., bilateral domain) and resample its values on an image manifold. We introduce a new formulation of Hermite radial basis function (HRBF) interpolation to obtain the scalar field in the bilateral domain. In contrast to previous implicit methods, bilateral HRBF (BHRBF) generates a segmentation boundary that passes through all contours, fits high-contrast image edges if they exist, and has a smooth shape in blurred areas of images. We also propose an acceleration scheme for computing B-HRBF to support a real-time and intuitive segmentation interface. In our experiments, we achieved high-quality segmentation results for regions of interest with high-contrast edges and blurred boundaries.
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    Physics Storyboards
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Ha, Sehoon; McCann, Jim; Liu, C. Karen; Popovic, Jovan; I. Navazo, P. Poulin
    Physical simulation and other procedural methods are increasingly popular tools in interactive applications because they generate complex and reactive behaviors given only a few parameter settings. This automation accelerates initial implementation, but also introduces a need to tune the available parameters until the desired behaviors emerge. These adjustments are typically performed iteratively, with the designer repeatedly running- and interacting with-the procedural animation with different parameter settings. Such a process is inaccurate, time consuming, and requires deep understanding and intuition, as parameters often have complex, nonlinear effects. Instead, we propose that designers construct physics storyboards to accelerate the process of tuning interactive, procedural animations. Physics storyboards are collections of space-time snapshots that highlight critical events and outcomes. They can be used to summarize the effects of parameter changes (without requiring the designer to perform extensive play-testing); and-when augmented with designer-provided evaluation functions-allow automatic parameter selection. We describe our implementation of this method, including how we use sampling to ensure that our automatically-selected parameters generalize, and how we time-warp user input to adapt it to changing parameters. We validate our implementation by using it to perform various design tasks in three example games.
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    Stylized and Performative Gaze for Character Animation
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Pejsa, Tomislav; Mutlu, Bilge; Gleicher, Michael; I. Navazo, P. Poulin
    Existing models of gaze motion for character animation simulate human movements, incorporating anatomical, neurophysiological, and functional constraints. While these models enable the synthesis of humanlike gaze motion, they only do so in characters that conform to human anatomical proportions, causing undesirable artifacts such as cross-eyedness in characters with non-human or exaggerated human geometry. In this paper, we extend a state-of-the- art parametric model of human gaze motion with control parameters for specifying character geometry, gaze dynamics, and performative characteristics in order to create an enhanced model that supports gaze motion in characters with a wide range of geometric properties that is free of these artifacts. The model also affords ''staging effects'' by offering softer functional constraints and more control over the appearance of the character's gaze movements. An evaluation study showed that the model, compared with the state-of-the-art model, creates gaze motion with fewer artifacts in characters with non-human or exaggerated human geometry while retaining their naturalness and communicative accuracy.
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    Animal Locomotion Controllers From Scratch
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Wampler, Kevin; Popovic, Jovan; Popovic, Zoran; I. Navazo, P. Poulin
    There exists a large body of research devoted to creating real time interactive locomotion controllers which are targeted at some specific class of character, most often humanoid bipeds. Relatively little work, however, has been done on approaches which are applicable to creatures with a wide range of different forms - partially due to the lack of easily obtainable motion-capture data for animals and fictional creatures. We show how a locomotion controller can be created despite this dearth of data by synthesizing it from scratch. Our method only requires as input a description of the shape of the animal, the gaits which it can perform, and a model of the task or tasks for which the controller will be used. From this a sequence of motion clips are automatically synthesized and assembled into a motion graph which defines a physically realistic controller capable of performing the specified tasks. The method attempts to minimize the computational time required to generate this controller and we show its effectiveness at creating interactive controllers for a range of tasks for bipeds, tripeds, and quadrupeds.
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    Gaze-driven Object Tracking for Real Time Rendering
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Mantiuk, Radoslaw; Bazyluk, Bartosz; Mantiuk, Rafal K.; I. Navazo, P. Poulin
    To efficiently deploy eye-tracking within 3D graphics applications, we present a new probabilistic method that predicts the patterns of user's eye fixations in animated 3D scenes from noisy eye-tracker data. The proposed method utilises both the eye-tracker data and the known information about the 3D scene to improve the accuracy, robustness and stability. Eye-tracking can thus be used, for example, to induce focal cues via gaze-contingent depth-of-field rendering, add intuitive controls to a video game, and create a highly reliable scene-aware saliency model. The computed probabilities rely on the consistency of the gaze scan-paths to the position and velocity of a moving or stationary target. The temporal characteristic of eye fixations is imposed by a Hidden Markov model, which steers the solution towards the most probable fixation patterns. The derivation of the algorithm is driven by the data from two eye-tracking experiments: the first experiment provides actual eye-tracker readings and the position of the target to be tracked. The second experiment is used to derive a JND-scaled (Just Noticeable Difference) quality metric that quantifies the perceived loss of quality due to the errors of the tracking algorithm. Data from both experiments are used to justify design choices, and to calibrate and validate the tracking algorithms. This novel method outperforms commonly used fixation algorithms and is able to track objects smaller then the nominal error of an eye-tracker.
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    Freeform Shadow Boundary Editing
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Mattausch, Oliver; Igarashi, Takeo; Wimmer, Michael; I. Navazo, P. Poulin
    We present an algorithm for artistically modifying physically based shadows. With our tool, an artist can directly edit the shadow boundaries in the scene in an intuitive fashion similar to freeform curve editing. Our algorithm then makes these shadow edits consistent with respect to varying light directions and scene configurations, by creating a shadow mesh from the new silhouettes. The shadow mesh helps a modified shadow volume algorithm cast shadows that conform to the artistic shadow boundary edits, while providing plausible interaction with dynamic environments, including animation of both characters and light sources. Our algorithm provides significantly more fine-grained local and direct control than previous artistic light editing methods, which makes it simple to adjust the shadows in a scene to reach a particular effect, or to create interesting shadow shapes and shadow animations. All cases are handled with a single intuitive interface, be it soft shadows, or (self-)shadows on arbitrary receivers.
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    Material Editing in Complex Scenes by Surface Light Field Manipulation and Reflectance Optimization
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Nguyen, Chuong H.; Scherzer, Daniel; Ritschel, Tobias; Seidel, Hans-Peter; I. Navazo, P. Poulin
    This work addresses the challenge of intuitive appearance editing in scenes with complex geometric layout and complex, spatially-varying indirect lighting. In contrast to previous work, that aimed to edit surface reflectance, our system allows a user to freely manipulate the surface light field. It then finds the best surface reflectance that ''explains'' the surface light field manipulation. Instead of classic L2 fitting of reflectance to a combination of incoming and exitant illumination, our system infers a sparse L0 change of shading parameters instead. Consequently, our system does not require ''diffuse'' or ''glossiness'' brushes or any such understanding of the underlying reflectance parametrization. Instead, it infers reflectance changes from scribbles made by a single simple color brush tool alone: Drawing a highlight will increase Phong specular; blurring a mirror reflection will decrease glossiness; etc. A sparse-solver framework operating on a novel point-based, pre-convolved lighting representation in combination with screen-space edit upsampling allows to perform editing interactively on a GPU.
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    A Correlated Parts Model for Object Detection in Large 3D Scans
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Sunkel, Martin; Jansen, Silke; Wand, Michael; Seidel, Hans-Peter; I. Navazo, P. Poulin
    This paper addresses the problem of detecting objects in 3D scans according to object classes learned from sparse user annotation. We model objects belonging to a class by a set of fully correlated parts, encoding dependencies between local shapes of different parts as well as their relative spatial arrangement. For an efficient and comprehensive retrieval of instances belonging to a class of interest, we introduce a new approximate inference scheme and a corresponding planning procedure. We extend our technique to hierarchical composite structures, reducing training effort and modeling spatial relations between detected instances. We evaluate our method on a number of real-world 3D scans and demonstrate its benefits as well as the performance of the new inference algorithm.
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    Interactive Facades - Analysis and Synthesis of Semi-Regular Facades
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) AlHalawani, Sawsan; Yang, Yong-Liang; Liu, Han; Mitra, Niloy J.; I. Navazo, P. Poulin
    Urban facades regularly contain interesting variations due to allowed deformations of repeated elements (e.g., windows in different open or close positions) posing challenges to state-of-the-art facade analysis algorithms. We propose a semi-automatic framework to recover both repetition patterns of the elements and their individual deformation parameters to produce a factored facade representation. Such a representation enables a range of applications including interactive facade images, improved multi-view stereo reconstruction, facade-level change detection, and novel image editing possibilities.
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    Smart Variations: Functional Substructures for Part Compatibility
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Zheng, Youyi; Cohen-Or, Daniel; Mitra, Niloy J.; I. Navazo, P. Poulin
    As collections of 3D models continue to grow, reusing model parts allows generation of novel model variations. Naïvely swapping parts across models, however, leads to implausible results, especially when mixing parts across different model families. Hence, the user has to manually ensure that the final model remains functionally valid. We claim that certain symmetric functional arrangements (SFARR-s), which are special arrangements among symmetrically related substructures, bear close relation to object functions. Hence, we propose a purely geometric approach based on such substructures to match, replace, and position triplets of parts to create non-trivial, yet functionally plausible, model variations. We demonstrate that starting even from a small set of models such a simple geometric approach can produce a diverse set of non-trivial and plausible model variations.
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    Surface Reconstruction through Point Set Structuring
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Lafarge, Florent; Alliez, Pierre; I. Navazo, P. Poulin
    We present a method for reconstructing surfaces from point sets. The main novelty lies in a structure-preserving approach where the input point set is first consolidated by structuring and resampling the planar components, before reconstructing the surface from both the consolidated components and the unstructured points. The final surface is obtained through solving a graph-cut problem formulated on the 3D Delaunay triangulation of the structured point set where the tetrahedra are labeled as inside or outside cells. Structuring facilitates the surface reconstruction as the point set is substantially reduced and the points are enriched with structural meaning related to adjacency between primitives. Our approach departs from the common dichotomy between smooth/piecewisesmooth and primitive-based representations by gracefully combining canonical parts from detected primitives and free-form parts of the inferred shape. Our experiments on a variety of inputs illustrate the potential of our approach in terms of robustness, flexibility and efficiency.
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    ArtiSketch: A System for Articulated Sketch Modeling
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Levi, Zohar; Gotsman, Craig; I. Navazo, P. Poulin
    We present ArtiSketch - a system which allows the conversion of a wealth of existing 2D content into 3D content by users who do not necessarily possess artistic skills. Using ArtiSketch, a novice user may describe a 3D model as a set of articulated 2D sketches of a shape from different viewpoints. ArtiSketch then automatically converts the sketches to an articulated 3D object. Using common interactive tools, the user provides an initial estimate of the 3D skeleton pose for each frame, which ArtiSketch refines to be consistent between frames. This skeleton may then be manipulated independently to generate novel poses of the 3D model.
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    Geosemantic Snapping for Sketch-Based Modeling
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Shtof, Alex; Agathos, Alexander; Gingold, Yotam; Shamir, Ariel; Cohen-Or, Daniel; I. Navazo, P. Poulin
    Modeling 3D objects from sketches is a process that requires several challenging problems including segmentation, recognition and reconstruction. Some of these tasks are harder for humans and some are harder for the machine. At the core of the problem lies the need for semantic understanding of the shape's geometry from the sketch. In this paper we propose a method to model 3D objects from sketches by utilizing humans specifically for semantic tasks that are very simple for humans and extremely difficult for the machine, while utilizing the machine for tasks that are harder for humans. The user assists recognition and segmentation by choosing and placing specific geometric primitives on the relevant parts of the sketch. The machine first snaps the primitive to the sketch by fitting its projection to the sketch lines, and then improves the model globally by inferring geosemantic constraints that link the different parts. The fitting occurs in real-time, allowing the user to be only as precise as needed to have a good starting configuration for this non-convex optimization problem. We evaluate the accessibility of our approach with a user study.
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    Stroke Parameterization
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Schmidt, Ryan; I. Navazo, P. Poulin
    We present a novel algorithm for generating a planar parameterization of the region surrounding a curve embedded in a 3D surface, which we call a stroke parameterization. The technique, which extends the well-known Discrete Exponential Map [SGW06], uses the same basic geometric transformations and hence is both efficient and easy-to-implement. We also handle self-intersecting curves, for which a 1-1 map between the original surface and the plane is not possible. Stroke parameterizations provide an ideal coordinate space for solving a variety of computer graphics problems. We present applications including tiling texture and displacement along 3D brush strokes, procedural texturing along 3D paths, and user-guided crease extraction.
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    Pose Space Image Based Rendering
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Hilsmann, Anna; Fechteler, Philipp; Eisert, Peter; I. Navazo, P. Poulin
    This paper introduces a new image-based rendering approach for articulated objects with complex pose-dependent appearance, such as clothes. Our approach combines body-pose-dependent appearance and geometry to synthesize images of new poses from a database of examples. A geometric model allows animation and view interpolation, while small details as well as complex shading and reflection properties are modeled by pose-dependent appearance examples in a database. Correspondences between the images are represented as mesh-based warps, both in the spatial and intensity domain. For rendering, these warps are interpolated in pose space, i.e. the space of body poses, using scattered data interpolation methods. Warp estimation as well as geometry reconstruction is performed in an offline procedure, thus shifting computational complexity to an a-priori training phase.
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    Capturing Relightable Human Performances under General Uncontrolled Illumination
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Li, Guannan; Wu, Chenglei; Stoll, Carsten; Liu, Yebin; Varanasi, Kiran; Dai, Qionghai; Theobalt, Christian; I. Navazo, P. Poulin
    We present a novel approach to create relightable free-viewpoint human performances from multi-view video recorded under general uncontrolled and uncalibated illumination.We first capture a multi-view sequence of an actor wearing arbitrary apparel and reconstruct a spatio-temporal coherent coarse 3D model of the performance using a marker-less tracking approach. Using these coarse reconstructions, we estimate the low-frequency component of the illumination in a spherical harmonics (SH) basis as well as the diffuse reflectance, and then utilize them to estimate the dynamic geometry detail of human actors based on shading cues. Given the high-quality time-varying geometry, the estimated illumination is extended to the all-frequency domain by re-estimating it in the wavelet basis. Finally, the high-quality all-frequency illumination is utilized to reconstruct the spatially-varying BRDF of the surface. The recovered time-varying surface geometry and spatially-varying non-Lambertian reflectance allow us to generate high-quality model-based free view-point videos of the actor under novel illumination conditions. Our method enables plausible reconstruction of relightable dynamic scene models without a complex controlled lighting apparatus, and opens up a path towards relightable performance capture in less constrained environments and using less complex acquisition setups.
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    Capture and Statistical Modeling of Arm-Muscle Deformations
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Neumann, Thomas; Varanasi, Kiran; Hasler, Nils; Wacker, Markus; Magnor, Marcus; Theobalt, Christian; I. Navazo, P. Poulin
    We present a comprehensive data-driven statistical model for skin and muscle deformation of the human shoulderarm complex. Skin deformations arise from complex bio-physical effects such as non-linear elasticity of muscles, fat, and connective tissue; and vary with physiological constitution of the subjects and external forces applied during motion. Thus, they are hard to model by direct physical simulation. Our alternative approach is based on learning deformations from multiple subjects performing different exercises under varying external forces. We capture the training data through a novel multi-camera approach that is able to reconstruct fine-scale muscle detail in motion. The resulting reconstructions from several people are aligned into one common shape parametrization, and learned using a semi-parametric non-linear method. Our learned data-driven model is fast, compact and controllable with a small set of intuitive parameters - pose, body shape and external forces, through which a novice artist can interactively produce complex muscle deformations. Our method is able to capture and synthesize fine-scale muscle bulge effects to a greater level of realism than achieved previously. We provide quantitative and qualitative validation of our method.
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    Fleshing: Spine-driven Bending with Local Volume Preservation
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Zhuo, Wei; Rossignac, Jarek; I. Navazo, P. Poulin
    Several design and animation techniques use a one-dimensional proxyC (a spine curve in 3D) to control the deformation or behavior of a digital model of a 3D shape S. We propose a modification of these ''skinning'' techniques that ensures local volume preservation, which is important for the physical plausibility of digital simulations. In the proposed ''fleshing'' techniques, as input, we consider a smooth spine C0, a model S0 of a solid that lies ''sufficiently close'' to C0, and a deformed version C1 of C0 that is ''not overly bent''. (We provide a precise characterization of these restrictions.) As output, we produce a bijective mapping M, that maps any point X of S onto a point M(X) of M(S). M satisfies two properties: (1) The closest projection of X on C0 and of M(X) on C1 have the same arc length parameter. (2) U and M(U) have the same volume, where U is any subset of S. We provide three different closed form expressions for radial, normal and binormal fleshing and discuss the details of their practical real-time implementation.
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    Computing and Fabricating Multiplanar Models
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Chen, Desai; Sitthi-amorn, Pitchaya; Lan, Justin T.; Matusik, Wojciech; I. Navazo, P. Poulin
    We present a method for converting computer 3D models into physical equivalents. More specifically, we address the problem of approximating a 3D textured mesh using a small number of planar polygonal primitives that form a closed surface. This simplified representation allows us to easily manufacture individual components using computer controlled cutters (e.g., laser cutters or CNC machines). These polygonal pieces can be assembled into the final 3D model using internal planar connectors that are manufactured simultaneously. Our shape approximation algorithm iteratively assigns mesh faces to planar segments and slowly deforms these faces towards corresponding segments. This approach ensures that the output for a given closed mesh is still a closed mesh and avoids introducing self-intersections. After this step we also compute the shape of polygonal connectors that internally hold the whole mesh surface. Both the polygonal surface elements and connectors can be manufactured in a single cutting pass. We validate the use of our method by computing and manufacturing a variety of textured polyhedral models.
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    Interactive Exploration and Flattening of Deformed Historical Documents
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Pal, Kazim; Terras, Melissa; Weyrich, Tim; I. Navazo, P. Poulin
    We present an interactive application for browsing severely damaged documents and other cultural artefacts. Such documents often contain strong geometric distortions such as wrinkling, buckling, and shrinking and cannot be flattened physically due to the high risk of causing further damage. Previous methods for virtual restoration involve globally flattening a 3D reconstruction of the document to produce a static image. We show how this global approach can fail in cases of severe geometric distortion, and instead propose an interactive viewer which allows a user to browse a document while dynamically flattening only the local region under inspection. Our application also records the provenance of the reconstruction by displaying the reconstruction side by side with the original image data.
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    Fabrication-aware Design with Intersecting Planar Pieces
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Schwartzburg, Yuliy; Pauly, Mark; I. Navazo, P. Poulin
    We propose a computational design approach to generate 3D models composed of interlocking planar pieces. We show how intricate 3D forms can be created by sliding the pieces into each other along straight slits, leading to a simple construction that does not require glue, screws, or other means of support. To facilitate the design process, we present an abstraction model that formalizes the main geometric constraints imposed by fabrication and assembly, and incorporates conditions on the rigidity of the resulting structure.We show that the tight coupling of constraints makes manual design highly nontrivial and introduce an optimization method to automate constraint satisfaction based on an analysis of the constraint relation graph. This algorithm ensures that the planar parts can be fabricated and assembled. We demonstrate the versatility of our approach by creating 3D toy models, an architectural design study, and several examples of functional furniture.
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    Measurement-Based Synthesis of Facial Microgeometry
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Graham, Paul; Tunwattanapong, Borom; Busch, Jay; Yu, Xueming; Jones, Andrew; Debevec, Paul; Ghosh, Abhijeet; I. Navazo, P. Poulin
    We present a technique for generating microstructure-level facial geometry by augmenting a mesostructure-level facial scan with detail synthesized from a set of exemplar skin patches scanned at much higher resolution. Additionally, we make point-source reflectance measurements of the skin patches to characterize the specular reflectance lobes at this smaller scale and analyze facial reflectance variation at both the mesostructure and microstructure scales. We digitize the exemplar patches with a polarization-based computational illumination technique which considers specular reflection and single scattering. The recorded microstructure patches can be used to synthesize full-facial microstructure detail for either the same subject or to a different subject. We show that the technique allows for greater realism in facial renderings including more accurate reproduction of skin's specular reflection effects.
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    Scalable Music: Automatic Music Retargeting and Synthesis
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Wenner, Simon; Bazin, Jean-Charles; Sorkine-Hornung, Alexander; Kim, Changil; Gross, Markus; I. Navazo, P. Poulin
    In this paper we propose a method for dynamic rescaling of music, inspired by recent works on image retargeting, video reshuffling and character animation in the computer graphics community. Given the desired target length of a piece of music and optional additional constraints such as position and importance of certain parts, we build on concepts from seam carving, video textures and motion graphs and extend them to allow for a global optimization of jumps in an audio signal. Based on an automatic feature extraction and spectral clustering for segmentation, we employ length-constrained least-costly path search via dynamic programming to synthesize a novel piece of music that best fulfills all desired constraints, with imperceptible transitions between reshuffled parts. We show various applications of music retargeting such as part removal, decreasing or increasing music duration, and in particular consistent joint video and audio editing.
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    By-example Synthesis of Curvilinear Structured Patterns
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Zhou, Shizhe; Lasram, Anass; Lefebvre, Sylvain; I. Navazo, P. Poulin
    Many algorithms in Computer Graphics require to synthesize a pattern along a curve. This is for instance the case with line stylization, to decorate objects with elaborate patterns (chains, laces, scratches), or to synthesize curvilinear features such as mountain ridges, rivers or roads. We describe a simple yet effective method for this problem. Our method addresses the main challenge of maintaining the continuity of the pattern while following the curve. It allows some freedom to the synthesized pattern: It may locally diverge from the curve so as to allow for a more natural global result. This also lets the pattern escape areas of overlaps or fold-overs. This makes our method particularly well suited to structured, detailed patterns following complex curves. Our synthesizer copies tilted pieces of the exemplar along the curve, following its orientation. The result is optimized through a shortest path search, with dynamic programming. We speed up the process by an efficient parallel implementation. Finally, since discontinuities may always remain we propose an optional post-processing step optimally deforming neighboring pieces to smooth the transitions.
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    A Particle-Grid Method for Opaque Ice Formation
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Im, Jaeho; Park, Hanwook; Kim, Jong-Hyun; Kim, Chang-Hun; I. Navazo, P. Poulin
    This paper presents a particle-grid method to simulate the generation of opaque ice which has air bubbles in it. Water temperature is diffused over a grid, and the exchange of dissolved air between ice and water particles is simulated. We render a particle as an air bubble if it has sufficient air. Otherwise, it is treated as a cloudy volume by distributing air into dissolved air field when the final state has been reached. In addition, our method includes a model in which heat transfer rate may change across the grid. Unlike previous models which could generate an ice volume of only fixed shapes, our approach uses signed distance function (SDF) to generate opaque ice volumes stored in containers of various geometric shapes and can render needle-shaped or egg-shaped bubbles.
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    Example-based Interpolation and Synthesis of Bidirectional Texture Functions
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Ruiters, Roland; Schwartz, Christopher; Klein, Reinhard; I. Navazo, P. Poulin
    Bidirectional Texture Functions (BTF) have proven to be a well-suited representation for the reproduction of measured real-world surface appearance and provide a high degree of realism. We present an approach for designing novel materials by interpolating between several measured BTFs. For this purpose, we transfer concepts from existing texture interpolation methods to the much more complex case of material interpolation. We employ a separation of the BTF into a heightmap and a parallax compensated BTF to cope with problems induced by parallax, masking and shadowing within the material. By working only on the factorized representation of the parallax compensated BTF and the heightmap, it is possible to efficiently perform the material interpolation. By this novel method to mix existing BTFs, we are able to design plausible and realistic intermediate materials for a large range of different opaque material classes. Furthermore, it allows for the synthesis of tileable and seamless BTFs and finally even the generation of gradually changing materials following user specified material distribution maps.
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    Geometry-Aware Volume-of-Fluid Method
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Cho, Junghyun; Ko, Hyeong-Seok; I. Navazo, P. Poulin
    We present a new framework to simulate moving interfaces in viscous incompressible two phase flows. The goal is to achieve both conservation of the fluid volume and a detailed reconstruction of the fluid surface. To these ends, we incorporate sub-grid refinement of the level set with the volume-of-fluid method. In the context of this refined level set grid we propose the algorithms needed for the coupling of the level set and the volume-of-fluid, which include techniques for computing volume, redistancing the level set, and handling surface tension. We report the experimental results produced with the proposed method via simulations of the two phase fluid phenomena such as air-cushioning and deforming large bubbles.
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    A Novel Projection Technique with Detail Capture and Shape Correction for Smoke Simulation
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Wu, Xiaoyue; Yang, Xubo; Yang, Yang; I. Navazo, P. Poulin
    Smoke simulation on a large grid is quite time consuming and most of the computation time is spent on the projection step.We present a novel projection method which produces quite similar visual results as those produced with the traditional projection method, but uses much less computation time. Our method includes two steps: detail-capture and shape-correction. The first step preserves most of the smoke details using an efficient DST (Discrete Sine Transformation) Poisson Solver with auxiliary boundary sweeping. The second step maintains the overall flow shape by solving a correcting Poisson equation on a coarse grid. Our algorithm is very fast and quite easy to implement. Experiments show that our projection is approximately 10-30 times faster than the traditional projection with PCG(Preconditioned Conjugate Gradient), while convincingly preserving both the flow details and the overall shape of the smoke.
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    Adaptive Quantization Visibility Caching
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Popov, Stefan; Georgiev, Iliyan; Slusallek, Philipp; Dachsbacher, Carsten; I. Navazo, P. Poulin
    Ray tracing has become a viable alternative to rasterization for interactive applications and also forms the basis of most global illumination methods. However, even today's fastest ray-tracers offer only a tight budget of rays per pixel per frame. Rendering performance can be improved by increasing this budget, or by developing methods that use it more efficiently. In this paper we propose a global visibility caching algorithm that reduces the number of shadow rays required for shading to a fraction of less than 2% in some cases. We quantize the visibility function's domain while ensuring a minimal degradation of the final image quality. To control the introduced error, we adapt the quantization locally, accounting for variations in geometry, sampling densities on both endpoints of the visibility queries, and the light signal itself. Compared to previous approaches for approximating visibility, e.g. shadow mapping, our method has several advantages: (1) it allows caching of arbitrary visibility queries between surface points and is thus applicable to all ray tracing based methods; (2) the approximation error is uniform over the entire image and can be bounded by a user-specified parameter; (3) the cache is created on-the-fly and does not waste any resources on queries that will never be used. We demonstrate the benefits of our method on Whitted-style ray tracing combined with instant radiosity, as well as an integration with bidirectional path tracing.
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    Analytic Visibility on the GPU
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Auzinger, Thomas; Wimmer, Michael; Jeschke, Stefan; I. Navazo, P. Poulin
    This paper presents a parallel, implementation-friendly analytic visibility method for triangular meshes. Together with an analytic filter convolution, it allows for a fully analytic solution to anti-aliased 3D mesh rendering on parallel hardware. Building on recent works in computational geometry, we present a new edge-triangle intersection algorithm and a novel method to complete the boundaries of all visible triangle regions after a hidden line elimination step. All stages of the method are embarrassingly parallel and easily implementable on parallel hardware. A GPU implementation is discussed and performance characteristics of the method are shown and compared to traditional sampling-based rendering methods.
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    Primitive Trees for Precomputed Distance Queries
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Lee, Sung-Ho; Park, Taejung; Kim, Chang-Hun; I. Navazo, P. Poulin
    We propose the primitive tree, a novel and compact space-partition method that samples and reconstructs a distance field with high accuracy, even for regions far from the surfaces. The primitive tree is based on the octree and stores the indices of the nearest primitives in its leaf nodes. Most previous approaches have involved a trade-off between accuracy and speed in distance queries, but our method can improve both aspects simultaneously. In addition, our method can sample unsigned distance fields effectively, even for self-intersecting and nonmanifold models. We present test results showing that our method can sample and represent large scenes, with more than ten million triangles, rapidly and accurately.
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    Landmark-Guided Elastic Shape Analysis of Spherically-Parameterized Surfaces
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Kurtek, Sebastian; Srivastava, Anuj; Klassen, Eric; Laga, Hamid; I. Navazo, P. Poulin
    We argue that full surface correspondence (registration) and optimal deformations (geodesics) are two related problems and propose a framework that solves them simultaneously. We build on the Riemannian shape analysis of anatomical and star-shaped surfaces of Kurtek et al. and focus on articulated complex shapes that undergo elastic deformations and that may contain missing parts. Our core contribution is the re-formulation of Kurtek et al.'s approach as a constrained optimization over all possible re-parameterizations of the surfaces, using a sparse set of corresponding landmarks. We introduce a landmark-constrained basis, which we use to numerically solve this optimization and therefore establish full surface registration and geodesic deformation between two surfaces. The length of the geodesic provides a measure of dissimilarity between surfaces. The advantages of this approach are: (1) simultaneous computation of full correspondence and geodesic between two surfaces, given a sparse set of matching landmarks (2) ability to handle more comprehensive deformations than nearly isometric, and (3) the geodesics and the geodesic lengths can be further used for symmetrizing 3D shapes and for computing their statistical averages. We validate the framework on challenging cases of large isometric and elastic deformations, and on surfaces with missing parts. We also provide multiple examples of averaging and symmetrizing 3D models.
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    Coupled Quasi-harmonic Bases
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Kovnatsky, Artiom; Bronstein, Michael M.; Bronstein, Alexander M.; Glashoff, Klaus; Kimmel, Ron; I. Navazo, P. Poulin
    The use of Laplacian eigenbases has been shown to be fruitful in many computer graphics applications. Today, state-of-the-art approaches to shape analysis, synthesis, and correspondence rely on these natural harmonic bases that allow using classical tools from harmonic analysis on manifolds. However, many applications involving multiple shapes are obstacled by the fact that Laplacian eigenbases computed independently on different shapes are often incompatible with each other. In this paper, we propose the construction of common approximate eigenbases for multiple shapes using approximate joint diagonalization algorithms, taking as input a set of corresponding functions (e.g. indicator functions of stable regions) on the two shapes. We illustrate the benefits of the proposed approach on tasks from shape editing, pose transfer, correspondence, and similarity.
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    Sparse Modeling of Intrinsic Correspondences
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Pokrass, Jonathan; Bronstein, Alexander M.; Bronstein, Michael M.; Sprechmann, Pablo; Sapiro, Guillermo; I. Navazo, P. Poulin
    We present a novel sparse modeling approach to non-rigid shape matching using only the ability to detect repeatable regions. As the input to our algorithm, we are given only two sets of regions in two shapes; no descriptors are provided so the correspondence between the regions is not know, nor we know how many regions correspond in the two shapes. We show that even with such scarce information, it is possible to establish very accurate correspondence between the shapes by using methods from the field of sparse modeling, being this, the first non-trivial use of sparse models in shape correspondence. We formulate the problem of permuted sparse coding, in which we solve simultaneously for an unknown permutation ordering the regions on two shapes and for an unknown correspondence in functional representation. We also propose a robust variant capable of handling incomplete matches. Numerically, the problem is solved efficiently by alternating the solution of a linear assignment and a sparse coding problem. The proposed methods are evaluated qualitatively and quantitatively on standard benchmarks containing both synthetic and scanned objects.
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    A Data-Driven Approach to Realistic Shape Morphing
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Gao, Lin; Lai, Yu-Kun; Huang, Qi-Xing; Hu, Shi-Min; I. Navazo, P. Poulin
    Morphing between 3D objects is a fundamental technique in computer graphics. Traditional methods of shape morphing focus on establishing meaningful correspondences and finding smooth interpolation between shapes. Such methods however only take geometric information as input and thus cannot in general avoid producing unnatural interpolation, in particular for large-scale deformations. This paper proposes a novel data-driven approach for shape morphing. Given a database with various models belonging to the same category, we treat them as data samples in the plausible deformation space. These models are then clustered to form local shape spaces of plausible deformations. We use a simple metric to reasonably represent the closeness between pairs of models. Given source and target models, the morphing problem is casted as a global optimization problem of finding a minimal distance path within the local shape spaces connecting these models. Under the guidance of intermediate models in the path, an extended as-rigid-as-possible interpolation is used to produce the final morphing. By exploiting the knowledge of plausible models, our approach produces realistic morphing for challenging cases as demonstrated by various examples in the paper.
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    Rendering Gigaray Light Fields
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Birklbauer, Clemens; Opelt, Simon; Bimber, Oliver; I. Navazo, P. Poulin
    We present a caching framework with a novel probability-based prefetching and eviction strategy applied to atomic cache units that enables interactive rendering of gigaray light fields. Further, we describe two new use cases that are supported by our framework: panoramic light fields, including a robust imaging technique and an appropriate parameterization scheme for real-time rendering and caching; and light-field-cached volume rendering, which supports interactive exploration of large volumetric datasets using light-field rendering. We consider applications such as light-field photography and the visualization of large image stacks from modern scanning microscopes.
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    View-Dependent Realtime Rendering of Procedural Facades with High Geometric Detail
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Krecklau, Lars; Born, Janis; Kobbelt, Leif; I. Navazo, P. Poulin
    We present an algorithm for realtime rendering of large-scale city models with procedurally generated facades. By using highly detailed assets like windows, doors, and decoration such city models can provide an extremely high geometric level of detail but on the downside they also consist of billions of polygons which makes it infeasible to even store them as explicit polygonal meshes. Moreover, when rendering urban scenes usually only a very small fraction of the city is actually visible which calls for effective culling mechanisms. For procedural textures there are efficient screen space techniques that evaluate, e.g., a split grammar on a per-pixel basis in the fragment shader and thus render a textured facade in a view dependent manner. We take this idea further by introducing 3D geometric detail in addition to flat textures. Our approach is a two-pass procedure that first renders a flat procedural facade. During rasterization the fragment shader triggers the instantiation of a detailed asset whenever a geometric facade element is potentially visible. The set of instantiated detail models are then rendered in a second pass. The major challenges arise from the fact that geometric details belonging to a facade can be visible even if the base polygon of the facade itself is not visible. Hence we propose measures to conservatively estimate visibility without introducing excessive redundancy. We further extend our technique by a simple level of detail mechanism that switches to baked textures (of the assets) depending on the distance to the camera. We demonstrate that our technique achieves realtime frame rates for large-scale city models with massive detail on current commodity graphics hardware.
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    Sharpening Out of Focus Images using High-Frequency Transfer
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Tao, Michael W.; Malik, Jitendra; Ramamoorthi, Ravi; I. Navazo, P. Poulin
    Focus misses are common in image capture, such as when the camera or the subject moves rapidly in sports and macro photography. One option to sharpen focus-missed photographs is through single image deconvolution, but high-frequency data cannot be fully recovered; therefore, artifacts such as ringing and amplified noise become apparent. We propose a new method that uses assisting, similar but different, sharp image(s) provided by the user (such as multiple images of the same subject in different positions captured using a burst of photographs). Our first contribution is to theoretically analyze the errors in three sources of data-a slightly sharpened original input image that we call the target, single image deconvolution with an aggressive inverse filter, and warped assisting image(s) registered using optical flow. We show that these three sources have different error characteristics, depending on image location and frequency band (for example, aggressive deconvolution is more accurate in high-frequency regions like edges). Next, we describe a practical method to compute these errors, given we have no ground truth and cannot easily work in the Fourier domain. Finally, we select the best source of data for a given pixel and scale in the Laplacian pyramid. We accurately transfer high-frequency data to the input, while minimizing artifacts. We demonstrate sharpened results on out-of-focus images in macro, sports, portrait and wildlife photography.
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    Analytic Rasterization of Curves with Polynomial Filters
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Manson, Josiah; Schaefer, Scott; I. Navazo, P. Poulin
    We present a method of analytically rasterizing shapes that have curved boundaries and linear color gradients using piecewise polynomial prefilters. By transforming the convolution of filters with the image from an integral over area into a boundary integral, we find closed-form expressions for rasterizing shapes. We show that a polynomial expression can be used to rasterize any combination of polynomial curves and filters. Our rasterizer also handles rational quadratic boundaries, which allows us to evaluate circles and ellipses. We apply our technique to rasterizing vector graphics and show that our derivation gives an efficient implementation as a scanline rasterizer.
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    Sifted Disks
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Ebeida, Mohamed S.; Mahmoud, Ahmed H.; Awad, Muhammad A.; Mohammed, Mohammed A.; Mitchell, Scott A.; Rand, Alexander; Owens, John D.; I. Navazo, P. Poulin
    We introduce the Sifted Disk technique for locally resampling a point cloud in order to reduce the number of points. Two neighboring points are removed and we attempt to find a single random point that is sufficient to replace them both. The resampling respects the original sizing function; In that sense it is not a coarsening. The angle and edge length guarantees of a Delaunay triangulation of the points are preserved. The sifted point cloud is still suitable for texture synthesis because the Fourier spectrum is largely unchanged. We provide an efficient algorithm, and demonstrate that sifting uniform Maximal Poisson-disk Sampling (MPS) and Delaunay Refinement (DR) points reduces the number of points by about 25 percent, and achieves a density about 1/3 more than the theoretical minimum. We show two-dimensional stippling and meshing applications to demonstrate the significance of the concept.