30-Issue 2

Permanent URI for this collection

https://diglib.eg.org/handle/10.2312/162
EG Proceedings

BibTeX (30-Issue 2)
                
@article{
https::/diglib.eg.org/handle/10.1111/000_preface_eg2011_awardwinners_keynotes,
-,

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

author = {},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
https://diglib.eg.org/handle/10.1111/000_preface_eg2011_awardwinners_keynotes}
-}

}
                
@article{
10.1111:j.1467-8659.2011.01855.x,

journal = {Computer Graphics Forum},
title = {{
The Natural 3D Spiral}},

author = {
Harary, Gur
 and 
Tal, Ayellet
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01855.x}

}
                
@article{
10.1111:j.1467-8659.2011.01856.x,

journal = {Computer Graphics Forum},
title = {{
Generalized Helicoids for Modeling Hair Geometry}},

author = {
Piuze, Emmanuel
 and 
Kry, Paul G.
 and 
Siddiqi, Kaleem
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01856.x}

}
                
@article{
10.1111:j.1467-8659.2011.01857.x,

journal = {Computer Graphics Forum},
title = {{
Fruit Senescence and Decay Simulation}},

author = {
Jr., Joseph T. Kider
 and 
Raja, Samantha
 and 
Badler, Norman I.
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01857.x}

}
                
@article{
10.1111:j.1467-8659.2011.01858.x,

journal = {Computer Graphics Forum},
title = {{
Learning Line Features in 3D Geometry}},

author = {
Sunkel, Martin
 and 
Jansen, Silke
 and 
Wand, Michael
 and 
Eisemann, Elmar
 and 
Seidel, Hans-Peter
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01858.x}

}
                
@article{
10.1111:j.1467-8659.2011.01859.x,

journal = {Computer Graphics Forum},
title = {{
Shape Analysis with Subspace Symmetries}},

author = {
Berner, Alexander
 and 
Wand, Michael
 and 
Mitra, Niloy J.
 and 
Mewes, Daniel
 and 
Seidel, Hans-Peter
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01859.x}

}
                
@article{
10.1111:j.1467-8659.2011.01885.x,

journal = {Computer Graphics Forum},
title = {{
Symmetry Hierarchy of Man-Made Objects}},

author = {
Wang, Yanzhen
 and 
Xu, Kai
 and 
Li, Jun
 and 
Zhang, Hao
 and 
Shamir, Ariel
 and 
Liu, Ligang
 and 
Cheng, Zhi-Quan
 and 
Xiong, Y.
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01885.x}

}
                
@article{
10.1111:j.1467-8659.2011.01861.x,

journal = {Computer Graphics Forum},
title = {{
RTSAH Traversal Order for Occlusion Rays}},

author = {
Ize, Thiago
 and 
Hansen, Charles
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01861.x}

}
                
@article{
10.1111:j.1467-8659.2011.01862.x,

journal = {Computer Graphics Forum},
title = {{
Two-Level Grids for Ray Tracing on GPUs}},

author = {
Kalojanov, Javor
 and 
Billeter, Markus
 and 
Slusallek, Philipp
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01862.x}

}
                
@article{
10.1111:j.1467-8659.2011.01863.x,

journal = {Computer Graphics Forum},
title = {{
Combinatorial Bidirectional Path-Tracing for Efficient Hybrid CPU/GPU Rendering}},

author = {
Pajot, Anthony
 and 
Barthe, Loïc
 and 
Paulin, Mathias
 and 
Poulin, Pierre
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01863.x}

}
                
@article{
10.1111:j.1467-8659.2011.01886.x,

journal = {Computer Graphics Forum},
title = {{
Guided ProceduralModeling}},

author = {
Bene , Bedrich
 and 
tava, Ondrej
 and 
Mech, Radomir
 and 
Miller, Gavin
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01886.x}

}
                
@article{
10.1111:j.1467-8659.2011.01864.x,

journal = {Computer Graphics Forum},
title = {{
Procedural Modeling of Interconnected Structures}},

author = {
Krecklau, Lars
 and 
Kobbelt, Leif
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01864.x}

}
                
@article{
10.1111:j.1467-8659.2011.01865.x,

journal = {Computer Graphics Forum},
title = {{
Interactive Modeling of City Layouts using Layers of Procedural Content}},

author = {
Lipp, Markus
 and 
Scherzer, Daniel
 and 
Wonka, Peter
 and 
Wimmer, Michael
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01865.x}

}
                
@article{
10.1111:j.1467-8659.2011.01867.x,

journal = {Computer Graphics Forum},
title = {{
Discovery of Intrinsic Primitives on Triangle Meshes}},

author = {
Solomon, Justin
 and 
Ben-Chen, Mirela
 and 
Butscher, Adrian
 and 
Guibas, Leonidas
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01867.x}

}
                
@article{
10.1111:j.1467-8659.2011.01868.x,

journal = {Computer Graphics Forum},
title = {{
Global Structure Optimization of Quadrilateral Meshes}},

author = {
Bommes, David
 and 
Lempfer, Timm
 and 
Kobbelt, Leif
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01868.x}

}
                
@article{
10.1111:j.1467-8659.2011.01866.x,

journal = {Computer Graphics Forum},
title = {{
SQuad: Compact Representation for Triangle Meshes}},

author = {
Gurung, Topraj
 and 
Laney, Daniel
 and 
Lindstrom, Peter
 and 
Rossignac, Jarek
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01866.x}

}
                
@article{
10.1111:j.1467-8659.2011.01887.x,

journal = {Computer Graphics Forum},
title = {{
Wavelet Rasterization}},

author = {
Manson, Josiah
 and 
Schaefer, Scott
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01887.x}

}
                
@article{
10.1111:j.1467-8659.2011.01869.x,

journal = {Computer Graphics Forum},
title = {{
Contouring Discrete Indicator Functions}},

author = {
Manson, Josiah
 and 
Smith, Jason
 and 
Schaefer, Scott
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01869.x}

}
                
@article{
10.1111:j.1467-8659.2011.01870.x,

journal = {Computer Graphics Forum},
title = {{
Freehand HDR Imaging of Moving Scenes with Simultaneous Resolution Enhancement}},

author = {
Zimmer, Henning
 and 
Bruhn, Andrés
 and 
Weickert, Joachim
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01870.x}

}
                
@article{
10.1111:j.1467-8659.2011.01871.x,

journal = {Computer Graphics Forum},
title = {{
Scalable Remote Rendering with Depth and Motion-flow Augmented Streaming}},

author = {
Paja, Dawid
 and 
Herzog, Robert
 and 
Eisemann, Elmar
 and 
Myszkowski, Karol
 and 
Seidel, Hans-Peter
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01871.x}

}
                
@article{
10.1111:j.1467-8659.2011.01888.x,

journal = {Computer Graphics Forum},
title = {{
Comprehensive Facial Performance Capture}},

author = {
Fyffe, Graham
 and 
Hawkins, Tim
 and 
Watts, Chris
 and 
Ma, Wan-Chun
 and 
Debevec, Paul
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01888.x}

}
                
@article{
10.1111:j.1467-8659.2011.01872.x,

journal = {Computer Graphics Forum},
title = {{
Langevin Particle: A Self-Adaptive Lagrangian Primitive for Flow Simulation Enhancement}},

author = {
Chen, Fan
 and 
Zhao, Ye
 and 
Yuan, Zhi
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01872.x}

}
                
@article{
10.1111:j.1467-8659.2011.01889.x,

journal = {Computer Graphics Forum},
title = {{
Deformable Motion: Squeezing into Cluttered Environments}},

author = {
Choi, Myung Geol
 and 
Kim, Manmyung
 and 
Hyun, Kyung Lyul
 and 
Lee, Jehee
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01889.x}

}
                
@article{
10.1111:j.1467-8659.2011.01873.x,

journal = {Computer Graphics Forum},
title = {{
BSSRDF Estimation from Single Images}},

author = {
Munoz, Adolfo
 and 
Echevarria, Jose I.
 and 
Seron, Francisco J.
 and 
Lopez-Moreno, Jorge
 and 
Glencross, Mashhuda
 and 
Gutierrez, Diego
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01873.x}

}
                
@article{
10.1111:j.1467-8659.2011.01890.x,

journal = {Computer Graphics Forum},
title = {{
A Sparse Parametric Mixture Model for BTF Compression, Editing and Rendering}},

author = {
Wu, Hongzhi
 and 
Dorsey, Julie
 and 
Rushmeier, Holly
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01890.x}

}
                
@article{
10.1111:j.1467-8659.2011.01891.x,

journal = {Computer Graphics Forum},
title = {{
Dynamic Display of BRDFs}},

author = {
Hullin, Matthias B.
 and 
Lensch, Hendrik P. A.
 and 
Raskar, Ramesh
 and 
Seidel, Hans-Peter
 and 
Ihrke, Ivo
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01891.x}

}
                
@article{
10.1111:j.1467-8659.2011.01874.x,

journal = {Computer Graphics Forum},
title = {{
Computer-Suggested Facial Makeup}},

author = {
Scherbaum, Kristina
 and 
Ritschel, Tobias
 and 
Hullin, Matthias
 and 
Thormählen, Thorsten
 and 
Blanz, Volker
 and 
Seidel, Hans-Peter
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01874.x}

}
                
@article{
10.1111:j.1467-8659.2011.01875.x,

journal = {Computer Graphics Forum},
title = {{
Predicted Virtual Soft Shadow Maps with High Quality Filtering}},

author = {
Shen, Li
 and 
Guennebaud, Gaël
 and 
Yang, Baoguang
 and 
Feng, Jieqing
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01875.x}

}
                
@article{
10.1111:j.1467-8659.2011.01876.x,

journal = {Computer Graphics Forum},
title = {{
Goal-based Caustics}},

author = {
Papas, Marios
 and 
Jarosz, Wojciech
 and 
Jakob, Wenzel
 and 
Rusinkiewicz, Szymon
 and 
Matusik, Wojciech
 and 
Weyrich, Tim
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01876.x}

}
                
@article{
10.1111:j.1467-8659.2011.01892.x,

journal = {Computer Graphics Forum},
title = {{
Implicit Brushes for Stylized Line-based Rendering}},

author = {
Vergne, Romain
 and 
Vanderhaeghe, David
 and 
Chen, Jiazhou
 and 
Barla, Pascal
 and 
Granier, Xavier
 and 
Schlick, Christophe
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01892.x}

}
                
@article{
10.1111:j.1467-8659.2011.01877.x,

journal = {Computer Graphics Forum},
title = {{
Estimating Color and Texture Parameters for Vector Graphics}},

author = {
Jeschke, Stefan
 and 
Cline, David
 and 
Wonka, Peter
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01877.x}

}
                
@article{
10.1111:j.1467-8659.2011.01878.x,

journal = {Computer Graphics Forum},
title = {{
Hatching for Motion Picture Production}},

author = {
Umenhoffer, Tamás
 and 
Szécsi, László
 and 
Szirmay-Kalos, László
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01878.x}

}
                
@article{
10.1111:j.1467-8659.2011.01893.x,

journal = {Computer Graphics Forum},
title = {{
Prior Knowledge for Part Correspondence}},

author = {
Kaick, Oliver van
 and 
Tagliasacchi, Andrea
 and 
Sidi, Oana
 and 
Zhang, Hao
 and 
Cohen-Or, Daniel
 and 
Wolf, Lior
 and 
Hamarneh, Ghassan
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01893.x}

}
                
@article{
10.1111:j.1467-8659.2011.01879.x,

journal = {Computer Graphics Forum},
title = {{
Intrinsic Shape Matching by Planned Landmark Sampling}},

author = {
Tevs, Art
 and 
Berner, Alexander
 and 
Wand, Michael
 and 
Ihrke, Ivo
 and 
Seidel, Hans-Peter
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01879.x}

}
                
@article{
10.1111:j.1467-8659.2011.01880.x,

journal = {Computer Graphics Forum},
title = {{
Component-wise Controllers for Structure-Preserving Shape Manipulation}},

author = {
Zheng, Youyi
 and 
Fu, Hongbo
 and 
Cohen-Or, Daniel
 and 
Au, Oscar Kin-Chung
 and 
Tai, Chiew-Lan
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01880.x}

}
                
@article{
10.1111:j.1467-8659.2011.01894.x,

journal = {Computer Graphics Forum},
title = {{
Blur-Aware Image Downsampling}},

author = {
Trentacoste, Matthew
 and 
Mantiuk, Rafal
 and 
Heidrich,  Wolfgang
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01894.x}

}
                
@article{
10.1111:j.1467-8659.2011.01881.x,

journal = {Computer Graphics Forum},
title = {{
Image Retargeting Quality Assessment}},

author = {
Liu, Yong-Jin
 and 
Luo, Xi
 and 
Xuan, Yu-Ming
 and 
Chen, Wen-Feng
 and 
Fu, Xiao-Lan
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01881.x}

}
                
@article{
10.1111:j.1467-8659.2011.01882.x,

journal = {Computer Graphics Forum},
title = {{
Image and Video Abstraction by Coherence-Enhancing Filtering}},

author = {
Kyprianidis, Jan Eric
 and 
Kang, Henry
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01882.x}

}
                
@article{
10.1111:j.1467-8659.2011.01895.x,

journal = {Computer Graphics Forum},
title = {{
Paint Mesh Cutting}},

author = {
Fan, Lubin
 and 
Liu, Ligang
 and 
Liu, Kun
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01895.x}

}
                
@article{
10.1111:j.1467-8659.2011.01883.x,

journal = {Computer Graphics Forum},
title = {{
GeoBrush: Interactive Mesh Geometry Cloning}},

author = {
Takayama, Kenshi
 and 
Schmidt, Ryan
 and 
Singh, Karan
 and 
Igarashi, Takeo
 and 
Boubekeur, Tamy
 and 
Sorkine, Olga
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01883.x}

}
                
@article{
10.1111:j.1467-8659.2011.01896.x,

journal = {Computer Graphics Forum},
title = {{
Walking On Broken Mesh: Defect-Tolerant Geodesic Distances and Parameterizations}},

author = {
Campen, Marcel
 and 
Kobbelt, Leif
},
year = {
2011},

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


ISSN = {1467-8659},

DOI = {
10.1111/j.1467-8659.2011.01896.x}

}

Browse

Recent Submissions

Now showing 1 - 41 of 41
  • Thumbnail Image
    Item
    Preface and Table of Contents
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Min Chen and Oliver Deussen
  • Thumbnail Image
    Item
    The Natural 3D Spiral
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Harary, Gur; Tal, Ayellet; M. Chen and O. Deussen
    Logarithmic spirals are ubiquitous in nature. This paper presents a novel mathematical definition of a 3D logarithmic spiral, which provides a proper description of objects found in nature. To motivate our work, we scanned spiral-shaped objects and studied their geometric properties. We consider the extent to which the existing 3D definitions capture these properties. We identify a property that is shared by the objects we investigated and is not satisfied by the existing 3D definitions. This leads us to present our definition in which both the radius of curvature and the radius of torsion change linearly along the curve. We prove that our spiral satisfies several desirable properties, including invariance to similarity transformations, smoothness, symmetry, extensibility, and roundness. Finally, we demonstrate the utility of our curves in the modeling of several animal structures.
  • Thumbnail Image
    Item
    Generalized Helicoids for Modeling Hair Geometry
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Piuze, Emmanuel; Kry, Paul G.; Siddiqi, Kaleem; M. Chen and O. Deussen
    In computer graphics, modeling the geometry of hair and hair-like patterns such as grass and fur remains a significant challenge. Hair strands can exist in an extensive variety of arrangements and the choice of an appropriate representation for tasks such as hair synthesis, fitting, editing, or reconstruction from samples, is non-trivial. To support such applications we present a novel mathematical representation of hair based on a class of minimal surfaces called generalized helicoids. This representation allows us to characterize the geometry of a single hair strand, as well as of those in its vicinity, by three intuitive curvature parameters and an elevation angle. We introduce algorithms for fitting piecewise generalized helicoids to unparameterized hair strands, and for interpolating hair between these fits. We showcase several applications of this representation including the synthesis of different hair geometries, wisp generation, hair interpolation from samples and hair-style parametrization and reconstruction from real hair data.
  • Thumbnail Image
    Item
    Fruit Senescence and Decay Simulation
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Jr., Joseph T. Kider; Raja, Samantha; Badler, Norman I.; M. Chen and O. Deussen
    Aging and imperfections provide important visual cues for realism. We present a novel physically-based approach for simulating the biological aging and decay process in fruits. This method simulates interactions between multiple processes. Our biologically-derived, reaction-diffusion model generates growth patterns for areas of fungal and bacterial infection. Fungal colony spread and propagation is affected by both bacterial growth and nutrient depletion. This process changes the physical properties of the surface of the fruit as well as its internal volume substrate. The fruit is physically simulated with parameters such as skin thickness and porosity, water content, flesh rigidity, ambient temperature, humidity, and proximity to other surfaces. Our model produces a simulation that closely mirrors the progression of decay in real fruits under similar parameterized conditions. Additionally, we provide a tool that allows artists to customize the input of the program to produce generalized fruit simulations.
  • Thumbnail Image
    Item
    Learning Line Features in 3D Geometry
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Sunkel, Martin; Jansen, Silke; Wand, Michael; Eisemann, Elmar; Seidel, Hans-Peter; M. Chen and O. Deussen
    Feature detection in geometric datasets is a fundamental tool for solving shape matching problems such as partial symmetry detection. Traditional techniques usually employ a priori models such as crease lines that are unspecific to the actual application. Our paper examines the idea of learning geometric features. We introduce a formal model for a class of linear feature constellations based on a Markov chain model and propose a novel, efficient algorithm for detecting a large number of features simultaneously. After a short user-guided training stage, in which one or a few example lines are sketched directly onto the input data, our algorithm automatically finds all pieces of geometry similar to the marked areas. In particular, the algorithm is able recognize larger classes of semantically similar but geometrically varying features, which is very difficult using unsupervised techniques. In a number of experiments, we apply our technique to point cloud data from 3D scanners. The algorithm is able to detect features with very low rates of false positives and negatives and to recognize broader classes of similar geometry (such as "windows" in a building scan) even from few training examples, thereby significantly improving over previous unsupervised techniques.
  • Thumbnail Image
    Item
    Shape Analysis with Subspace Symmetries
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Berner, Alexander; Wand, Michael; Mitra, Niloy J.; Mewes, Daniel; Seidel, Hans-Peter; M. Chen and O. Deussen
    We address the problem of partial symmetry detection, i.e., the identification of building blocks a complex shape is composed of. Previous techniques identify parts that relate to each other by simple rigid mappings, similarity transforms, or, more recently, intrinsic isometries. Our approach generalizes the notion of partial symmetries to more general deformations. We introduce subspace symmetries whereby we characterize similarity by requiring the set of symmetric parts to form a low dimensional shape space. We present an algorithm to discover subspace symmetries based on detecting linearly correlated correspondences among graphs of invariant features. We evaluate our technique on various data sets. We show that for models with pronounced surface features, subspace symmetries can be found fully automatically. For complicated cases, a small amount of user input is used to resolve ambiguities. Our technique computes dense correspondences that can subsequently be used in various applications, such as model repair and denoising.
  • Thumbnail Image
    Item
    Symmetry Hierarchy of Man-Made Objects
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Wang, Yanzhen; Xu, Kai; Li, Jun; Zhang, Hao; Shamir, Ariel; Liu, Ligang; Cheng, Zhi-Quan; Xiong, Y.; M. Chen and O. Deussen
    We introduce symmetry hierarchy of man-made objects, a high-level structural representation of a 3D model providing a symmetry-induced, hierarchical organization of the model's constituent parts. Given an input mesh, we segment it into primitive parts and build an initial graph which encodes inter-part symmetries and connectivity relations, as well as self-symmetries in individual parts. The symmetry hierarchy is constructed from the initial graph via recursive graph contraction which either groups parts by symmetry or assembles connected sets of parts. The order of graph contraction is dictated by a set of precedence rules designed primarily to respect the law of symmetry in perceptual grouping and the principle of compactness of representation. We show that symmetry hierarchy naturally implies a hierarchical segmentation that is more meaningful than those produced by local geometric considerations. We also develop an application of symmetry hierarchies for structural shape editing.
  • Thumbnail Image
    Item
    RTSAH Traversal Order for Occlusion Rays
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Ize, Thiago; Hansen, Charles; M. Chen and O. Deussen
    We accelerate the finding of occluders in tree based acceleration structures, such as a packetized BVH and a single ray kd-tree, by deriving the ray termination surface area heuristic (RTSAH) cost model for traversing an occlusion ray through a tree and then using the RTSAH to determine which child node a ray should traverse first instead of the traditional choice of traversing the near node before the far node. We further extend RTSAH to handle materials that attenuate light instead of fully occluding it, so that we can avoid superfluous intersections with partially transparent objects. For scenes with high occlusion, we substantially lower the number of traversal steps and intersection tests and achieve up to 2x speedups.
  • Thumbnail Image
    Item
    Two-Level Grids for Ray Tracing on GPUs
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Kalojanov, Javor; Billeter, Markus; Slusallek, Philipp; M. Chen and O. Deussen
    We investigate the use of two-level nested grids as acceleration structure for ray tracing of dynamic scenes. We propose a massively parallel, sort-based construction algorithm and show that the two-level grid is one of the structures that is fastest to construct on modern graphics processors. The structure handles non-uniform primitive distributions more robustly than the uniform grid and its traversal performance is comparable to those of other high quality acceleration structures used for dynamic scenes. We propose a cost model to determine the grid resolution and improve SIMD utilization during ray-triangle intersection by employing a hybrid packetization strategy. The build times and ray traversal acceleration provide overall rendering performance superior to previous approaches for real time rendering of animated scenes on GPUs.
  • Thumbnail Image
    Item
    Combinatorial Bidirectional Path-Tracing for Efficient Hybrid CPU/GPU Rendering
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Pajot, Anthony; Barthe, Loïc; Paulin, Mathias; Poulin, Pierre; M. Chen and O. Deussen
    This paper presents a reformulation of bidirectional path-tracing that adequately divides the algorithm into processes efficiently executed in parallel on both the CPU and the GPU. We thus benefit from high-level optimization techniques such as double buffering, batch processing, and asyncronous execution, as well as from the exploitation of most of the CPU, GPU, and memory bus capabilities. Our approach, while avoiding pure GPU implementation limitations (such as limited complexity of shaders, light or camera models, and processed scene data sets), is more than ten times faster than standard bidirectional path-tracing implementations, leading to performance suitable for production-oriented rendering engines.
  • Thumbnail Image
    Item
    Guided ProceduralModeling
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Bene , Bedrich; tava, Ondrej; Mech, Radomir; Miller, Gavin; M. Chen and O. Deussen
    Procedural methods present one of the most powerful techniques for authoring a vast variety of computer graphics models. However, their massive applicability is hindered by the lack of control and a low predictability of the results. In the classical procedural modeling pipeline, the user usually defines a set of rules, executes the procedural system, and by examining the results attempts to infer what should be changed in the system definition in order to achieve the desired output. We present guided procedural modeling, a new approach that allows a high level of top-down control by breaking the system into smaller building blocks that communicate. In our work we generalize the concept of the environment. The user creates a set of guides. Each guide defines a region in which a specific procedural model operates. These guides are connected by a set of links that serve for message passing between the procedural models attached to each guide. The entire model consists of a set of guides with procedural models, a graph representing their connection, and the method in which the guides interact. The modeling process is performed by modifying each of the described elements. The user can control the high-level description by editing the guides or manipulate the low-level description by changing the procedural rules. Changing the connectivity allows the user to create new complex forms in an easy and intuitive way. We show several examples of procedural structures, including an ornamental pattern, a street layout, a bridge, and a model of trees. We also demonstrate interactive examples for quick and intuitive editing using physics-based mass-spring system.
  • Thumbnail Image
    Item
    Procedural Modeling of Interconnected Structures
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Krecklau, Lars; Kobbelt, Leif; M. Chen and O. Deussen
    The complexity and detail of geometric scenes that are used in today's computer animated films and interactive games have reached a level where the manual creation by traditional 3D modeling tools has become infeasible. This is why procedural modeling concepts have been developed which generate highly complex 3D models by automatically executing a set of formal construction rules. Well-known examples are variants of L-systems which describe the bottom-up growth process of plants and shape grammars which define architectural buildings by decomposing blocks in a top-down fashion. However, none of these approaches allows for the easy generation of interconnected structures such as bridges or roller coasters where a functional interaction between rigid and deformable parts of an object is needed. Our approach mainly relies on the top-down decomposition principle of shape grammars to create an arbitrarily complex but well structured layout. During this process, potential attaching points are collected in containers which represent the set of candidates to establish interconnections. Our grammar then uses either abstract connection patterns or geometric queries to determine elements in those containers that are to be connected. The two different types of connections that our system supports are rigid object chains and deformable beams. The former type is constructed by inverse kinematics, the latter by spline interpolation. We demonstrate the descriptive power of our grammar by example models of bridges, roller coasters, and wall-mounted catenaries.
  • Thumbnail Image
    Item
    Interactive Modeling of City Layouts using Layers of Procedural Content
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Lipp, Markus; Scherzer, Daniel; Wonka, Peter; Wimmer, Michael; M. Chen and O. Deussen
    In this paper, we present new solutions for the interactive modeling of city layouts that combine the power of procedural modeling with the flexibility of manual modeling. Procedural modeling enables us to quickly generate large city layouts, while manual modeling allows us to hand-craft every aspect of a city. We introduce transformation and merging operators for both topology preserving and topology changing transformations based on graph cuts. In combination with a layering system, this allows intuitive manipulation of urban layouts using operations such as drag and drop, translation, rotation etc. In contrast to previous work, these operations always generate valid, i.e., intersection-free layouts. Furthermore, we introduce anchored assignments to make sure that modifications are persistent even if the whole urban layout is regenerated.
  • Thumbnail Image
    Item
    Discovery of Intrinsic Primitives on Triangle Meshes
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Solomon, Justin; Ben-Chen, Mirela; Butscher, Adrian; Guibas, Leonidas; M. Chen and O. Deussen
    The discovery of meaningful parts of a shape is required for many geometry processing applications, such as parameterization, shape correspondence, and animation. It is natural to consider primitives such as spheres, cylinders and cones as the building blocks of shapes, and thus to discover parts by fitting such primitives to a given surface. This approach, however, will break down if primitive parts have undergone almost-isometric deformations, as is the case, for example, for articulated human models. We suggest that parts can be discovered instead by finding intrinsic primitives, which we define as parts that posses an approximate intrinsic symmetry. We employ the recently-developed method of computing discrete approximate Killing vector fields (AKVFs) to discover intrinsic primitives by investigating the relationship between the AKVFs of a composite object and the AKVFs of its parts. We show how to leverage this relationship with a standard clustering method to extract k intrinsic primitives and remaining asymmetric parts of a shape for a given k. We demonstrate the value of this approach for identifying the prominent symmetry generators of the parts of a given shape. Additionally, we show how our method can be modified slightly to segment an entire surface without marking asymmetric connecting regions and compare this approach to state-of-the-art methods using the Princeton Segmentation Benchmark.
  • Thumbnail Image
    Item
    Global Structure Optimization of Quadrilateral Meshes
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Bommes, David; Lempfer, Timm; Kobbelt, Leif; M. Chen and O. Deussen
    We introduce a fully automatic algorithm which optimizes the high-level structure of a given quadrilateral mesh to achieve a coarser quadrangular base complex. Such a topological optimization is highly desirable, since stateof- the-art quadrangulation techniques lead to meshes which have an appropriate singularity distribution and an anisotropic element alignment, but usually they are still far away from the high-level structure which is typical for carefully designed meshes manually created by specialists and used e.g. in animation or simulation. In this paper we show that the quality of the high-level structure is negatively affected by helical configurations within the quadrilateral mesh. Consequently we present an algorithm which detects helices and is able to remove most of them by applying a novel grid preserving simplification operator (GP-operator) which is guaranteed to maintain an all-quadrilateral mesh. Additionally it preserves the given singularity distribution and in particular does not introduce new singularities. For each helix we construct a directed graph in which cycles through the start vertex encode operations to remove the corresponding helix. Therefore a simple graph search algorithm can be performed iteratively to remove as many helices as possible and thus improve the high-level structure in a greedy fashion. We demonstrate the usefulness of our automatic structure optimization technique by showing several examples with varying complexity.
  • Thumbnail Image
    Item
    SQuad: Compact Representation for Triangle Meshes
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Gurung, Topraj; Laney, Daniel; Lindstrom, Peter; Rossignac, Jarek; M. Chen and O. Deussen
    The SQuad data structure represents the connectivity of a triangle mesh by its "S table" of about 2 rpt (integer references per triangle). Yet it allows for a simple implementation of expected constant-time, random-access operators for traversing the mesh, including in-order traversal of the triangles incident upon a vertex. SQuad is more compact than the Corner Table (CT), which stores 6 rpt, and than the recently proposed SOT, which stores 3 rpt. However, in-core access is generally faster in CT than in SQuad, and SQuad requires rebuilding the S table if the connectivity is altered. The storage reduction and memory coherence opportunities it offers may help to reduce the frequency of page faults and cache misses when accessing elements of a mesh that does not fit in memory. We provide the details of a simple algorithm that builds the S table and of an optimized implementation of the SQuad operators.
  • Thumbnail Image
    Item
    Wavelet Rasterization
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Manson, Josiah; Schaefer, Scott; M. Chen and O. Deussen
    We present a method for analytically calculating an anti-aliased rasterization of arbitrary polygons or fonts bounded by Bezier curves in 2D as well as oriented triangle meshes in 3D. Our algorithm rasterizes multiple resolutions simultaneously using a hierarchical wavelet representation and is robust to degenerate inputs. We show that using the simplest wavelet, the Haar basis, is equivalent to performing a box-filter to the rasterized image. Because we evaluate wavelet coefficients through line integrals in 2D, we are able to derive analytic solutions for polygons that have Bezier curve boundaries of any order, and we provide solutions for quadratic and cubic curves. In 3D, we compute the wavelet coefficients through analytic surface integrals over triangle meshes and show how to do so in a computationally efficient manner.
  • Thumbnail Image
    Item
    Contouring Discrete Indicator Functions
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Manson, Josiah; Smith, Jason; Schaefer, Scott; M. Chen and O. Deussen
    We present a method for calculating the boundary of objects from Discrete Indicator Functions that store 2- material volume fractions with a high degree of accuracy. Although Marching Cubes and its derivatives are effective methods for calculating contours of functions sampled over discrete grids, these methods perform poorly when contouring non-smooth functions such as Discrete Indicator Functions. In particular, Marching Cubes will generate surfaces that exhibit aliasing and oscillations around the exact surface. We derive a simple solution to remove these problems by using a new function to calculate the positions of vertices along cell edges that is efficient, easy to implement, and does not require any optimization or iteration. Finally, we provide empirical evidence that the error introduced by our contouring method is significantly less than is introduced by Marching Cubes.
  • Thumbnail Image
    Item
    Freehand HDR Imaging of Moving Scenes with Simultaneous Resolution Enhancement
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Zimmer, Henning; Bruhn, Andrés; Weickert, Joachim; M. Chen and O. Deussen
    Despite their high popularity, common high dynamic range (HDR) methods are still limited in their practical applicability: They assume that the input images are perfectly aligned, which is often violated in practise. Our paper does not only free the user from this unrealistic limitation, but even turns the missing alignment into an advantage: By exploiting the multiple exposures, we can create a super-resolution image. The alignment step is performed by a modern energy-based optic flow approach that takes into account the varying exposure conditions. Moreover, it produces dense displacement fields with subpixel precision. As a consequence, our approach can handle arbitrary complex motion patterns, caused by severe camera shake and moving objects. Additionally, it benefits from several advantages over existing strategies: (i) It is robust under outliers (noise, occlusions, saturation problems) and allows for sharp discontinuities in the displacement field. (ii) The alignment step neither requires camera calibration nor knowledge of the exposure times. (iii) It can be efficiently implemented on CPU and GPU architectures. After the alignment is performed, we use the obtained subpixel accurate displacement fields as input for an energy-based, joint super-resolution and HDR (SR-HDR) approach. It introduces robust data terms and anisotropic smoothness terms in the SR-HDR literature. Our experiments with challenging real world data demonstrate that these novelties are pivotal for the favourable performance of our approach.
  • Thumbnail Image
    Item
    Scalable Remote Rendering with Depth and Motion-flow Augmented Streaming
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Paja, Dawid; Herzog, Robert; Eisemann, Elmar; Myszkowski, Karol; Seidel, Hans-Peter; M. Chen and O. Deussen
    In this paper, we focus on efficient compression and streaming of frames rendered from a dynamic 3D model. Remote rendering and on-the-fly streaming become increasingly attractive for interactive applications. Data is kept confidential and only images are sent to the client. Even if the client's hardware resources are modest, the user can interact with state-of-the-art rendering applications executed on the server. Our solution focuses on augmented video information, e.g., by depth, which is key to increase robustness with respect to data loss, image reconstruction, and is an important feature for stereo vision and other client-side applications. Two major challenges arise in such a setup. First, the server workload has to be controlled to support many clients, second the data transfer needs to be efficient. Consequently, our contributions are twofold. First, we reduce the server-based computations by making use of sparse sampling and temporal consistency to avoid expensive pixel evaluations. Second, our data-transfer solution takes limited bandwidths into account, is robust to information loss, and compression and decompression are efficient enough to support real-time interaction. Our key insight is to tailor our method explicitly for rendered 3D content and shift some computations on client GPUs, to better balance the server/client workload. Our framework is progressive, scalable, and allows us to stream augmented high-resolution (e.g., HDready) frames with small bandwidth on standard hardware.
  • Thumbnail Image
    Item
    Comprehensive Facial Performance Capture
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Fyffe, Graham; Hawkins, Tim; Watts, Chris; Ma, Wan-Chun; Debevec, Paul; M. Chen and O. Deussen
    We present a system for recording a live dynamic facial performance, capturing highly detailed geometry and spatially varying diffuse and specular reflectance information for each frame of the performance. The result is a reproduction of the performance that can be rendered from novel viewpoints and novel lighting conditions, achieving photorealistic integration into any virtual environment. Dynamic performances are captured directly, without the need for any template geometry or static geometry scans, and processing is completely automatic, requiring no human input or guidance. Our key contributions are a heuristic for estimating facial reflectance information from gradient illumination photographs, and a geometry optimization framework that maximizes a principled likelihood function combining multi-view stereo correspondence and photometric stereo, using multiresolution belief propagation. The output of our system is a sequence of geometries and reflectance maps, suitable for rendering in off-the-shelf software. We show results from our system rendered under novel viewpoints and lighting conditions, and validate our results by demonstrating a close match to ground truth photographs
  • Thumbnail Image
    Item
    Langevin Particle: A Self-Adaptive Lagrangian Primitive for Flow Simulation Enhancement
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Chen, Fan; Zhao, Ye; Yuan, Zhi; M. Chen and O. Deussen
    We develop a new Lagrangian primitive, named Langevin particle, to incorporate turbulent flow details in fluid simulation. A group of the particles are distributed inside the simulation domain based on a turbulence energy model with turbulence viscosity. A particle in particular moves obeying the generalized Langevin equation, a well known stochastic differential equation that describes the particle's motion as a random Markov process. The resultant particle trajectory shows self-adapted fluctuation in accordance to the turbulence energy, while following the global flow dynamics. We then feed back Langevin forces to the simulation based on the stochastic trajectory, which drive the flow with necessary turbulence. The new hybrid flow simulation method features nonrestricted particle evolution requiring minimal extra manipulation after initiation. The flow turbulence is easily controlled and the total computational overhead of enhancement is minimal based on typical fluid solvers.
  • Thumbnail Image
    Item
    Deformable Motion: Squeezing into Cluttered Environments
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Choi, Myung Geol; Kim, Manmyung; Hyun, Kyung Lyul; Lee, Jehee; M. Chen and O. Deussen
    We present an interactive method that allows animated characters to navigate through cluttered environments. Our characters are equipped with a variety of motion skills to clear obstacles, narrow passages, and highly constrained environment features. Our control method incorporates a behavior model into well-known, standard path planning algorithms. Our behavior model, called deformable motion, consists of a graph of motion capture fragments. The key idea of our approach is to add flexibility on motion fragments such that we can situate them into a cluttered environment via constraint-based formulation. We demonstrate our deformable motion for realtime interactive navigation and global path planning in highly constrained virtual environments.
  • Thumbnail Image
    Item
    BSSRDF Estimation from Single Images
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Munoz, Adolfo; Echevarria, Jose I.; Seron, Francisco J.; Lopez-Moreno, Jorge; Glencross, Mashhuda; Gutierrez, Diego; M. Chen and O. Deussen
    We present a novel method to estimate an approximation of the reflectance characteristics of optically thick, homogeneous translucent materials using only a single photograph as input. First, we approximate the diffusion profile as a linear combination of piecewise constant functions, an approach that enables a linear system minimization and maximizes robustness in the presence of suboptimal input data inferred from the image. We then fit to a smoother monotonically decreasing model, ensuring continuity on its first derivative. We show the feasibility of our approach and validate it in controlled environments, comparing well against physical measurements from previous works. Next, we explore the performance of our method in uncontrolled scenarios, where neither lighting nor geometry are known. We show that these can be roughly approximated from the corresponding image by making two simple assumptions: that the object is lit by a distant light source and that it is globally convex, allowing us to capture the visual appearance of the photographed material. Compared with previous works, our technique offers an attractive balance between visual accuracy and ease of use, allowing its use in a wide range of scenarios including off-the-shelf, single images, thus extending the current repertoire of real-world data acquisition techniques.
  • Thumbnail Image
    Item
    A Sparse Parametric Mixture Model for BTF Compression, Editing and Rendering
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Wu, Hongzhi; Dorsey, Julie; Rushmeier, Holly; M. Chen and O. Deussen
    Bidirectional texture functions (BTFs) represent the appearance of complex materials. Three major shortcomings with BTFs are the bulky storage, the difficulty in editing and the lack of efficient rendering methods. To reduce storage, many compression techniques have been applied to BTFs, but the results are difficult to edit. To facilitate editing, analytical models have been fit, but at the cost of accuracy of representation for many materials. It becomes even more challenging if efficient rendering is also needed. We introduce a high-quality general representation that is, at once, compact, easily editable, and can be efficiently rendered. The representation is computed by adopting the stagewise Lasso algorithm to search for a sparse set of analytical functions, whose weighted sum approximates the input appearance data. We achieve compression rates comparable to a state-of-the-art BTF compression method. We also demonstrate results in BTF editing and rendering.
  • Thumbnail Image
    Item
    Dynamic Display of BRDFs
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Hullin, Matthias B.; Lensch, Hendrik P. A.; Raskar, Ramesh; Seidel, Hans-Peter; Ihrke, Ivo; M. Chen and O. Deussen
    This paper deals with the challenge of physically displaying reflectance, i.e., the appearance of a surface and its variation with the observer position and the illuminating environment. This is commonly described by the bidirectional reflectance distribution function (BRDF). We provide a catalogue of criteria for the display of BRDFs, and sketch a few orthogonal approaches to solving the problem in an optically passive way. Our specific implementation is based on a liquid surface, on which we excite waves in order to achieve a varying degree of anisotropic roughness. The resulting probability density function of the surface normal is shown to follow a Gaussian distribution similar to most established BRDF models.
  • Thumbnail Image
    Item
    Computer-Suggested Facial Makeup
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Scherbaum, Kristina; Ritschel, Tobias; Hullin, Matthias; Thormählen, Thorsten; Blanz, Volker; Seidel, Hans-Peter; M. Chen and O. Deussen
    Finding the best makeup for a given human face is an art in its own right. Experienced makeup artists train for years to be skilled enough to propose a best-fit makeup for an individual. In this work we propose a system that automates this task. We acquired the appearance of 56 human faces, both without and with professional makeup. To this end, we use a controlled-light setup, which allows to capture detailed facial appearance information, such as diffuse reflectance, normals, subsurface-scattering, specularity, or glossiness. A 3D morphable face model is used to obtain 3D positional information and to register all faces into a common parameterization. We then define makeup to be the change of facial appearance and use the acquired database to find a mapping from the space of human facial appearance to makeup. Our main application is to use this mapping to suggest the best-fit makeup for novel faces that are not in the database. Further applications are makeup transfer, automatic rating of makeup, makeup-training, or makeup-exaggeration. As our makeup representation captures a change in reflectance and scattering, it allows us to synthesize faces with makeup in novel 3D views and novel lighting with high realism. The effectiveness of our approach is further validated in a user-study.
  • Thumbnail Image
    Item
    Predicted Virtual Soft Shadow Maps with High Quality Filtering
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Shen, Li; Guennebaud, Gaël; Yang, Baoguang; Feng, Jieqing; M. Chen and O. Deussen
    In this paper we present a novel image based algorithm to render visually plausible anti-aliased soft shadows in a robust and efficient manner. To achieve both high visual quality and high performance, it employs an accurate shadow map filtering method which guarantees smooth penumbrae and high quality anisotropic anti-aliasing of the sharp transitions. Unlike approaches based on pre-filtering approximations, our approach does not suffer from light bleeding or losing contact shadows. Discretization artefacts are avoided by creating virtual shadow maps on the fly according to a novel shadow map resolution prediction model. This model takes into account the screen space frequency of the penumbrae via a perceptual metric which has been directly established from an appropriate user study. Consequently, our algorithm always generates shadow maps with minimal resolutions enabling high performance while guarantying high quality. Thanks to this perceptual model, our algorithm can sometimes be faster at rendering soft shadows than hard shadows. It can render game-like scenes at very high frame rates, and extremely large and complex scenes such as CAD models at interactive rates. In addition, our algorithm is highly scalable, and the quality versus performance trade-off can be easily tweaked.
  • Thumbnail Image
    Item
    Goal-based Caustics
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Papas, Marios; Jarosz, Wojciech; Jakob, Wenzel; Rusinkiewicz, Szymon; Matusik, Wojciech; Weyrich, Tim; M. Chen and O. Deussen
    We propose a novel system for designing and manufacturing surfaces that produce desired caustic images when illuminated by a light source. Our system is based on a nonnegative image decomposition using a set of possibly overlapping anisotropic Gaussian kernels. We utilize this decomposition to construct an array of continuous surface patches, each of which focuses light onto one of the Gaussian kernels, either through refraction or reflection. We show how to derive the shape of each continuous patch and arrange them by performing a discrete assignment of patches to kernels in the desired caustic. Our decomposition provides for high fidelity reconstruction of natural images using a small collection of patches. We demonstrate our approach on a wide variety of caustic images by manufacturing physical surfaces with a small number of patches.
  • Thumbnail Image
    Item
    Implicit Brushes for Stylized Line-based Rendering
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Vergne, Romain; Vanderhaeghe, David; Chen, Jiazhou; Barla, Pascal; Granier, Xavier; Schlick, Christophe; M. Chen and O. Deussen
    We introduce a new technique called Implicit Brushes to render animated 3D scenes with stylized lines in realtime with temporal coherence. An Implicit Brush is defined at a given pixel by the convolution of a brush footprint along a feature skeleton; the skeleton itself is obtained by locating surface features in the pixel neighborhood. Features are identified via image-space fitting techniques that not only extract their location, but also their profile, which permits to distinguish between sharp and smooth features. Profile parameters are then mapped to stylistic parameters such as brush orientation, size or opacity to give rise to a wide range of line-based styles.
  • Thumbnail Image
    Item
    Estimating Color and Texture Parameters for Vector Graphics
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Jeschke, Stefan; Cline, David; Wonka, Peter; M. Chen and O. Deussen
    Diffusion curves are a powerful vector graphic representation that stores an image as a set of 2D Bezier curves with colors defined on either side. These colors are diffused over the image plane, resulting in smooth color regions as well as sharp boundaries. In this paper, we introduce a new automatic diffusion curve coloring algorithm. We start by defining a geometric heuristic for the maximum density of color control points along the image curves. Following this, we present a new algorithm to set the colors of these points so that the resulting diffused image is as close as possible to a source image in a least squares sense. We compare our coloring solution to the existing one which fails for textured regions, small features, and inaccurately placed curves. The second contribution of the paper is to extend the diffusion curve representation to include texture details based on Gabor noise. Like the curves themselves, the defined texture is resolution independent, and represented compactly. We define methods to automatically make an initial guess for the noise texure, and we provide intuitive manual controls to edit the parameters of the Gabor noise. Finally, we show that the diffusion curve representation itself extends to storing any number of attributes in an image, and we demonstrate this functionality with image stippling an hatching applications.
  • Thumbnail Image
    Item
    Hatching for Motion Picture Production
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Umenhoffer, Tamás; Szécsi, László; Szirmay-Kalos, László; M. Chen and O. Deussen
    This paper presents a hatching algorithm which - while also allows for an implementation in real-time - is integrated into the production pipeline of computer generated motion picture. Motion picture production pipelines impose special functional and quality requirements. From the functional point of view, the stages of modeling, 3D rendering, and compositing form a pipeline without feed-back, and frames are rendered independently, possibly on different computers. Thus, no temporal data can be shared between them while flicker free animation needs to be generated. Quality requirements can be grasped as that of dual consistency: the generated hatching must consistently follow object movement and deformation, and, at the same time, it should have a consistent pattern and density in image-space to provide the hand-crafted look. In order to meet both requirements, we apply a particle based method and develop an image-space density control mechanism using rejection sampling and low- discrepancy sequences. We also discuss the decomposition of rendering tasks according to the main stages of the production pipeline and demonstrate how the artist can define the illustration style in a convenient way.
  • Thumbnail Image
    Item
    Prior Knowledge for Part Correspondence
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Kaick, Oliver van; Tagliasacchi, Andrea; Sidi, Oana; Zhang, Hao; Cohen-Or, Daniel; Wolf, Lior; Hamarneh, Ghassan; M. Chen and O. Deussen
    Classical approaches to shape correspondence base their computation purely on the properties, in particular geometric similarity, of the shapes in question. Their performance still falls far short of that of humans in challenging cases where corresponding shape parts may differ significantly in geometry or even topology. We stipulate that in these cases, shape correspondence by humans involves recognition of the shape parts where prior knowledge on the parts would play a more dominant role than geometric similarity. We introduce an approach to part correspondence which incorporates prior knowledge imparted by a training set of pre-segmented, labeled models and combines the knowledge with content-driven analysis based on geometric similarity between the matched shapes. First, the prior knowledge is learned from the training set in the form of per-label classifiers. Next, given two query shapes to be matched, we apply the classifiers to assign a probabilistic label to each shape face. Finally, by means of a joint labeling scheme, the probabilistic labels are used synergistically with pairwise assignments derived from geometric similarity to provide the resulting part correspondence. We show that the incorporation of knowledge is especially effective in dealing with shapes exhibiting large intra-class variations. We also show that combining knowledge and content analyses outperforms approaches guided by either attribute alone.
  • Thumbnail Image
    Item
    Intrinsic Shape Matching by Planned Landmark Sampling
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Tevs, Art; Berner, Alexander; Wand, Michael; Ihrke, Ivo; Seidel, Hans-Peter; M. Chen and O. Deussen
    Recently, the problem of intrinsic shape matching has received a lot of attention. A number of algorithms have been proposed, among which random-sampling-based techniques have been particularly successful due to their generality and efficiency. We introduce a new sampling-based shape matching algorithm that uses a planning step to find optimized "landmark" points. These points are matched first in order to maximize the information gained and thus minimize the sampling costs. Our approach makes three main contributions: First, the new technique leads to a significant improvement in performance, which we demonstrate on a number of benchmark scenarios. Second, our technique does not require any keypoint detection. This is often a significant limitation for models that do not show sufficient surface features. Third, we examine the actual numerical degrees of freedom of the matching problem for a given piece of geometry. In contrast to previous results, our estimates take into account unprecise geodesics and potentially numerically unfavorable geometry of general topology, giving a more realistic complexity estimate.
  • Thumbnail Image
    Item
    Component-wise Controllers for Structure-Preserving Shape Manipulation
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Zheng, Youyi; Fu, Hongbo; Cohen-Or, Daniel; Au, Oscar Kin-Chung; Tai, Chiew-Lan; M. Chen and O. Deussen
    Recent shape editing techniques, especially for man-made models, have gradually shifted focus from maintaining local, low-level geometric features to preserving structural, high-level characteristics like symmetry and parallelism. Such new editing goals typically require a pre-processing shape analysis step to enable subsequent shape editing. Observing that most editing of shapes involves manipulating their constituent components, we introduce component-wise controllers that are adapted to the component characteristics inferred from shape analysis. The controllers capture the natural degrees of freedom of individual components and thus provide an intuitive user interface for editing. A typical model usually results in a moderate number of controllers, allowing easy establishment of semantic relations among them by automatic shape analysis supplemented with user interaction. We propose a component-wise propagation algorithm to automatically preserve the established inter-relations while maintaining the defining characteristics of individual controllers and respecting the user-specified modeling constraints. We extend these ideas to a hierarchical setup, allowing the user to adjust the tool complexity with respect to the desired modeling complexity. We demonstrate the effectiveness of our technique on a wide range of manmade models with structural features, often containing multiple connected pieces.
  • Thumbnail Image
    Item
    Blur-Aware Image Downsampling
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Trentacoste, Matthew; Mantiuk, Rafal; Heidrich, Wolfgang; M. Chen and O. Deussen
    Resizing to a lower resolution can alter the appearance of an image. In particular, downsampling an image causes blurred regions to appear sharper. It is useful at times to create a downsampled version of the image that gives the same impression as the original, such as for digital camera viewfinders. To understand the effect of blur on image appearance at different image sizes, we conduct a perceptual study examining how much blur must be present in a downsampled image to be perceived the same as the original. We find a complex, but mostly image-independent relationship between matching blur levels in images at different resolutions. The relationship can be explained by a model of the blur magnitude analyzed as a function of spatial frequency. We incorporate this model in a new appearance-preserving downsampling algorithm, which alters blur magnitude locally to create a smaller image that gives the best reproduction of the original image appearance.
  • Thumbnail Image
    Item
    Image Retargeting Quality Assessment
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Liu, Yong-Jin; Luo, Xi; Xuan, Yu-Ming; Chen, Wen-Feng; Fu, Xiao-Lan; M. Chen and O. Deussen
    Content-aware image retargeting is a technique that can flexibly display images with different aspect ratios and simultaneously preserve salient regions in images. Recently many image retargeting techniques have been proposed. To compare image quality by different retargeting methods fast and reliably, an objective metric simulating the human vision system (HVS) is presented in this paper. Different from traditional objective assessment methods that work in bottom-up manner (i.e., assembling pixel-level features in a local-to-global way), in this paper we propose to use a reverse order (top-down manner) that organizes image features from global to local viewpoints, leading to a new objective assessment metric for retargeted images. A scale-space matching method is designed to facilitate extraction of global geometric structures from retargeted images. By traversing the scale space from coarse to fine levels, local pixel correspondence is also established. The objective assessment metric is then based on both global geometric structures and local pixel correspondence. To evaluate color images, CIE L*a*b* color space is utilized. Experimental results are obtained to measure the performance of objective assessments with the proposed metric. The results show good consistency between the proposed objective metric and subjective assessment by human observers.
  • Thumbnail Image
    Item
    Image and Video Abstraction by Coherence-Enhancing Filtering
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Kyprianidis, Jan Eric; Kang, Henry; M. Chen and O. Deussen
    In this work, we present a non-photorealistic rendering technique to create stylized abstractions from color images and videos. Our approach is based on adaptive line integral convolution in combination with directional shock filtering. The smoothing process regularizes directional image features while the shock filter provides a sharpening effect. Both operations are guided by a flow field derived from the structure tensor. To obtain a high-quality flow field, we present a novel smoothing scheme for the structure tensor based on Poisson's equation. Our approach effectively regularizes anisotropic image regions while preserving the overall image structure and achieving a consistent level of abstraction. Moreover, it is suitable for per-frame filtering of video and can be efficiently implemented to process content in real-time.
  • Thumbnail Image
    Item
    Paint Mesh Cutting
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Fan, Lubin; Liu, Ligang; Liu, Kun; M. Chen and O. Deussen
    We present a novel progressive painting-based mesh cut out tool, called Paint Mesh Cutting, for interactive mesh segmentation. Different from the previous user interfaces, the user only needs to draw a single stroke on the foreground region and then obtains the desired cutting part at an interactive rate. Moreover, the user progressively paints the region of interest using a brush and has the instant feedback on cutting results as he/she drags the mouse. This is achieved by efficient local graph-cut based optimizations based on the Gaussian mixture models (GMM) on the shape diameter function (SDF) metric of the shape. We demonstrate a number of various examples to illustrate the flexibility and applicability of our system and present a user study that supports the advantages of our user interface.
  • Thumbnail Image
    Item
    GeoBrush: Interactive Mesh Geometry Cloning
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Takayama, Kenshi; Schmidt, Ryan; Singh, Karan; Igarashi, Takeo; Boubekeur, Tamy; Sorkine, Olga; M. Chen and O. Deussen
    We propose a method for interactive cloning of 3D surface geometry using a paintbrush interface, similar to the continuous cloning brush popular in image editing. Existing interactive mesh composition tools focus on atomic copy-and-paste of pre-selected feature areas, and are either limited to copying surface displacements, or require the solution of variational optimization problems, which is too expensive for an interactive brush interface. In contrast, our GeoBrush method supports real-time continuous copying of arbitrary high-resolution surface features between irregular meshes, including topological handles. We achieve this by first establishing a correspondence between the source and target geometries using a novel generalized discrete exponential map parameterization. Next we roughly align the source geometry with the target shape using Green Coordinates with automaticallyconstructed cages. Finally, we compute an offset membrane to smoothly blend the pasted patch with C1 continuity before stitching it into the target. The offset membrane is a solution of a bi-harmonic PDE, which is computed on the GPU in real time by exploiting the regular parametric domain. We demonstrate the effectiveness of GeoBrush with various editing scenarios, including detail enrichment and completion of scanned surfaces.
  • Thumbnail Image
    Item
    Walking On Broken Mesh: Defect-Tolerant Geodesic Distances and Parameterizations
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Campen, Marcel; Kobbelt, Leif; M. Chen and O. Deussen
    Efficient methods to compute intrinsic distances and geodesic paths have been presented for various types of surface representations, most importantly polygon meshes. These meshes are usually assumed to be well-structured and manifold. In practice, however, they often contain defects like holes, gaps, degeneracies, non-manifold configurations - or they might even be just a soup of polygons. The task of repairing these defects is computationally complex and in many cases exhibits various ambiguities demanding tedious manual efforts. We present a computational framework that enables the computation of meaningful approximate intrinsic distances and geodesic paths on raw meshes in a way which is tolerant to such defects. Holes and gaps are bridged up to a user-specified tolerance threshold such that distances can be computed plausibly even across multiple connected components of inconsistent meshes. Further, we show ways to locally parameterize a surface based on geodesic distance fields, easily facilitating the application of textures and decals on raw meshes. We do all this without explicitly repairing the input, thereby avoiding the costly additional efforts. In order to enable broad applicability we provide details on two implementation variants, one optimized for performance, the other optimized for memory efficiency. Using the presented framework many applications can readily be extended to deal with imperfect meshes. Since we abstract from the input applicability is not even limited to meshes, other representations can be handled as well.