33-Issue 7

Permanent URI for this collection


Preface and Table of Contents


Environment-Adaptive Contact Poses for Virtual Characters

Kang, Changgu
Lee, Sung-Hee

Data-Driven Reconstruction of Human Locomotion Using a Single Smartphone

Eom, Haegwang
Choi, Byungkuk
Noh, Junyong

Editing and Synthesizing Two-Character Motions using a Coupled Inverted Pendulum Model

Hwang, Jaepyung
Suh, Il Hong
Kwon, Taesoo

Locomotion Skills for Insects with Sample-based Controller

Guo, Shihui
Chang, Jian
Yang, Xiaosong
Wang, Wencheng
Zhang, Jianjun

A Data-Driven Framework for Visual Crowd Analysis

Charalambous, Panayiotis
Karamouzas, Ioannis
Guy, Stephen J.
Chrysanthou, Yiorgos

shade.js: Adaptive Material Descriptions

Sons, Kristian
Klein, Felix
Sutter, Jan
Slusallek, Philipp

Using Physically Based Rendering to Benchmark Structured Light Scanners

Medeiros, Esdras
Doraiswamy, Harish
Berger, Matthew
Silva, Claudio T.

Sky Based Light Metering for High Dynamic Range Images

Gryaditskya, Yulia
Pouli, Tania
Reinhard, Erik
Seidel, Hans-Peter

Sub-Pixel Anti-Aliasing Via Triangle-Based Geometry Reconstruction

Du, Wenjun
Feng, Jieqing
Yang, Baoguang

Template-Based Sampling of Anisotropic BRDFs

Filip, Jiri
Vávra, Radomir

Interactive Image-Guided Modeling of Extruded Shapes

Cao, Yan-Pei
Ju, Tao
Fu, Zhao
Hu, Shi-Min

Anisotropic Geodesics for Live-wire Mesh Segmentation

Zhuang, Yixin
Zou, Ming
Carr, Nathan
Ju, Tao

Multiple Shape Correspondence by Dynamic Programming

Sahillioglu, Yusuf
Yemez, Yucel

Approximate Symmetry Detection in Partial 3D Meshes

Sipiran, Ivan
Gregor, Robert
Schreck, Tobias

Structure Aware Visual Cryptography

Liu, Bin
Martin, Ralph R.
Huang, Ji-Wu
Hu, Shi-Min

G2 Surface Interpolation Over General Topology Curve Networks

Salvi, Péter
Várady, Tamás

Polyline-sourced Geodesic Voronoi Diagrams on Triangle Meshes

Xu, Chunxu
Liu, Yong-Jin
Sun, Qian
Li, Jinyan
He, Ying

Fast and Scalable Mesh Superfacets

Simari, Patricio
Picciau, Giulia
Floriani, Leila De

Adaptive Multi-scale Analysis for Point-based Surface Editing

Nader, Georges
Guennebaud, Gael
Mellado, Nicolas

Fractional Reyes-Style Adaptive Tessellation for Continuous Level of Detail

Liktor, Gabor
Pan, Minghao
Dachsbacher, Carsten

Hybrid Particle-grid Modeling for Multi-scale Droplet/Spray Simulation

Yang, Lipeng
Li, Shuai
Hao, Aimin
Qin, Hong

Advanced Hybrid Particle-Grid Method with Sub-Grid Particle Correction

Um, Kiwon
Baek, Seungho
Han, JungHyun

Incompressible SPH using the Divergence-Free Condition

Kang, Nahyup
Sagong, Donghoon

Real-Time Symmetry-Preserving Deformation

Wu, Xiaokun
Wand, Michael
Hildebrandt, Klaus
Kohli, Pushmeet
Seidel, Hans-Peter

Sparse Localized Decomposition of Deformation Gradients

Huang, Zhichao
Yao, Junfeng
Zhong, Zichun
Liu, Yang
Guo, Xiaohu

2D-3D Lifting for Shape Reconstruction

Nan, Liangliang
Sharf, Andrei
Chen, Baoquan

Realistic Road Path Reconstruction from GIS Data

Nguyen, Hoang Ha
Desbenoit, Brett
Daniel, Marc

Efficient Depth Propagation for Constructing a Layered Depth Image from a Single Image

Iizuka, Satoshi
Endo, Yuki
Kanamori, Yoshihiro
Mitani, Jun
Fukui, Yukio

Automatic 3D Indoor Scene Updating with RGBD Cameras

Liu, Zhenbao
Tang, Sicong
Xu, Weiwei
Bu, Shuhui
Han, Junwei
Zhou, Kun

Making in-Front-of Cars Transparent: Sharing First-Person-Views via Dashcam

Chen, Shao-Chi
Chen, Hsin-Yi
Chen, Yi-Ling
Tsai, Hsin-Mu
Chen, Bing-Yu

Learning Natural Colors for Image Recoloring

Huang, Hao-Zhi
Zhang, Song-Hai
Martin, Ralph R.
Hu, Shi-Min

Perceptually-based Color Assignment

Kim, Hye-Rin
Yoo, Min-Joon
Kang, Henry
Lee, In-Kwon

Illuminant Aware Gamut-Based Color Transfer

Nguyen, Rang M. H.
Kim, Seon Joo
Brown, Michael S.

Single-shot High Dynamic Range Imaging Using Coded Electronic Shutter

Cho, Hojin
Kim, Seon Joo
Lee, Seungyong

Fast Feature-Oriented Visual Connection for Large Image Collections

Yan, Qingan
Xu, Zhan
Xiao, Chunxia

Perceptually-motivated Stereoscopic Film Grain

Templin, Krzysztof
Didyk, Piotr
Myszkowski, Karol
Seidel, Hans-Peter

Time-Lapse Photometric Stereo and Applications

Shen, Fangyang
Sunkavalli, Kalyan
Bonneel, Nicolas
Rusinkiewicz, Szymon
Pfister, Hanspeter
Tong, Xin


BibTeX (33-Issue 7)
                
@article{
10.1111:cgf.12468,
journal = {Computer Graphics Forum}, title = {{
Environment-Adaptive Contact Poses for Virtual Characters}},
author = {
Kang, Changgu
and
Lee, Sung-Hee
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12468}
}
                
@article{
10.1111:cgf.12469,
journal = {Computer Graphics Forum}, title = {{
Data-Driven Reconstruction of Human Locomotion Using a Single Smartphone}},
author = {
Eom, Haegwang
and
Choi, Byungkuk
and
Noh, Junyong
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12469}
}
                
@article{
10.1111:cgf.12470,
journal = {Computer Graphics Forum}, title = {{
Editing and Synthesizing Two-Character Motions using a Coupled Inverted Pendulum Model}},
author = {
Hwang, Jaepyung
and
Suh, Il Hong
and
Kwon, Taesoo
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12470}
}
                
@article{
10.1111:cgf.12471,
journal = {Computer Graphics Forum}, title = {{
Locomotion Skills for Insects with Sample-based Controller}},
author = {
Guo, Shihui
and
Chang, Jian
and
Yang, Xiaosong
and
Wang, Wencheng
and
Zhang, Jianjun
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12471}
}
                
@article{
10.1111:cgf.12472,
journal = {Computer Graphics Forum}, title = {{
A Data-Driven Framework for Visual Crowd Analysis}},
author = {
Charalambous, Panayiotis
and
Karamouzas, Ioannis
and
Guy, Stephen J.
and
Chrysanthou, Yiorgos
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12472}
}
                
@article{
10.1111:cgf.12473,
journal = {Computer Graphics Forum}, title = {{
shade.js: Adaptive Material Descriptions}},
author = {
Sons, Kristian
and
Klein, Felix
and
Sutter, Jan
and
Slusallek, Philipp
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12473}
}
                
@article{
10.1111:cgf.12475,
journal = {Computer Graphics Forum}, title = {{
Using Physically Based Rendering to Benchmark Structured Light Scanners}},
author = {
Medeiros, Esdras
and
Doraiswamy, Harish
and
Berger, Matthew
and
Silva, Claudio T.
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12475}
}
                
@article{
10.1111:cgf.12474,
journal = {Computer Graphics Forum}, title = {{
Sky Based Light Metering for High Dynamic Range Images}},
author = {
Gryaditskya, Yulia
and
Pouli, Tania
and
Reinhard, Erik
and
Seidel, Hans-Peter
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12474}
}
                
@article{
10.1111:cgf.12476,
journal = {Computer Graphics Forum}, title = {{
Sub-Pixel Anti-Aliasing Via Triangle-Based Geometry Reconstruction}},
author = {
Du, Wenjun
and
Feng, Jieqing
and
Yang, Baoguang
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12476}
}
                
@article{
10.1111:cgf.12477,
journal = {Computer Graphics Forum}, title = {{
Template-Based Sampling of Anisotropic BRDFs}},
author = {
Filip, Jiri
and
Vávra, Radomir
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12477}
}
                
@article{
10.1111:cgf.12478,
journal = {Computer Graphics Forum}, title = {{
Interactive Image-Guided Modeling of Extruded Shapes}},
author = {
Cao, Yan-Pei
and
Ju, Tao
and
Fu, Zhao
and
Hu, Shi-Min
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12478}
}
                
@article{
10.1111:cgf.12479,
journal = {Computer Graphics Forum}, title = {{
Anisotropic Geodesics for Live-wire Mesh Segmentation}},
author = {
Zhuang, Yixin
and
Zou, Ming
and
Carr, Nathan
and
Ju, Tao
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12479}
}
                
@article{
10.1111:cgf.12480,
journal = {Computer Graphics Forum}, title = {{
Multiple Shape Correspondence by Dynamic Programming}},
author = {
Sahillioglu, Yusuf
and
Yemez, Yucel
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12480}
}
                
@article{
10.1111:cgf.12481,
journal = {Computer Graphics Forum}, title = {{
Approximate Symmetry Detection in Partial 3D Meshes}},
author = {
Sipiran, Ivan
and
Gregor, Robert
and
Schreck, Tobias
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12481}
}
                
@article{
10.1111:cgf.12482,
journal = {Computer Graphics Forum}, title = {{
Structure Aware Visual Cryptography}},
author = {
Liu, Bin
and
Martin, Ralph R.
and
Huang, Ji-Wu
and
Hu, Shi-Min
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12482}
}
                
@article{
10.1111:cgf.12483,
journal = {Computer Graphics Forum}, title = {{
G2 Surface Interpolation Over General Topology Curve Networks}},
author = {
Salvi, Péter
and
Várady, Tamás
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12483}
}
                
@article{
10.1111:cgf.12484,
journal = {Computer Graphics Forum}, title = {{
Polyline-sourced Geodesic Voronoi Diagrams on Triangle Meshes}},
author = {
Xu, Chunxu
and
Liu, Yong-Jin
and
Sun, Qian
and
Li, Jinyan
and
He, Ying
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12484}
}
                
@article{
10.1111:cgf.12486,
journal = {Computer Graphics Forum}, title = {{
Fast and Scalable Mesh Superfacets}},
author = {
Simari, Patricio
and
Picciau, Giulia
and
Floriani, Leila De
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12486}
}
                
@article{
10.1111:cgf.12485,
journal = {Computer Graphics Forum}, title = {{
Adaptive Multi-scale Analysis for Point-based Surface Editing}},
author = {
Nader, Georges
and
Guennebaud, Gael
and
Mellado, Nicolas
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12485}
}
                
@article{
10.1111:cgf.12487,
journal = {Computer Graphics Forum}, title = {{
Fractional Reyes-Style Adaptive Tessellation for Continuous Level of Detail}},
author = {
Liktor, Gabor
and
Pan, Minghao
and
Dachsbacher, Carsten
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12487}
}
                
@article{
10.1111:cgf.12488,
journal = {Computer Graphics Forum}, title = {{
Hybrid Particle-grid Modeling for Multi-scale Droplet/Spray Simulation}},
author = {
Yang, Lipeng
and
Li, Shuai
and
Hao, Aimin
and
Qin, Hong
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12488}
}
                
@article{
10.1111:cgf.12489,
journal = {Computer Graphics Forum}, title = {{
Advanced Hybrid Particle-Grid Method with Sub-Grid Particle Correction}},
author = {
Um, Kiwon
and
Baek, Seungho
and
Han, JungHyun
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12489}
}
                
@article{
10.1111:cgf.12490,
journal = {Computer Graphics Forum}, title = {{
Incompressible SPH using the Divergence-Free Condition}},
author = {
Kang, Nahyup
and
Sagong, Donghoon
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12490}
}
                
@article{
10.1111:cgf.12491,
journal = {Computer Graphics Forum}, title = {{
Real-Time Symmetry-Preserving Deformation}},
author = {
Wu, Xiaokun
and
Wand, Michael
and
Hildebrandt, Klaus
and
Kohli, Pushmeet
and
Seidel, Hans-Peter
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12491}
}
                
@article{
10.1111:cgf.12492,
journal = {Computer Graphics Forum}, title = {{
Sparse Localized Decomposition of Deformation Gradients}},
author = {
Huang, Zhichao
and
Yao, Junfeng
and
Zhong, Zichun
and
Liu, Yang
and
Guo, Xiaohu
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12492}
}
                
@article{
10.1111:cgf.12493,
journal = {Computer Graphics Forum}, title = {{
2D-3D Lifting for Shape Reconstruction}},
author = {
Nan, Liangliang
and
Sharf, Andrei
and
Chen, Baoquan
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12493}
}
                
@article{
10.1111:cgf.12494,
journal = {Computer Graphics Forum}, title = {{
Realistic Road Path Reconstruction from GIS Data}},
author = {
Nguyen, Hoang Ha
and
Desbenoit, Brett
and
Daniel, Marc
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12494}
}
                
@article{
10.1111:cgf.12496,
journal = {Computer Graphics Forum}, title = {{
Efficient Depth Propagation for Constructing a Layered Depth Image from a Single Image}},
author = {
Iizuka, Satoshi
and
Endo, Yuki
and
Kanamori, Yoshihiro
and
Mitani, Jun
and
Fukui, Yukio
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12496}
}
                
@article{
10.1111:cgf.12495,
journal = {Computer Graphics Forum}, title = {{
Automatic 3D Indoor Scene Updating with RGBD Cameras}},
author = {
Liu, Zhenbao
and
Tang, Sicong
and
Xu, Weiwei
and
Bu, Shuhui
and
Han, Junwei
and
Zhou, Kun
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12495}
}
                
@article{
10.1111:cgf.12497,
journal = {Computer Graphics Forum}, title = {{
Making in-Front-of Cars Transparent: Sharing First-Person-Views via Dashcam}},
author = {
Chen, Shao-Chi
and
Chen, Hsin-Yi
and
Chen, Yi-Ling
and
Tsai, Hsin-Mu
and
Chen, Bing-Yu
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12497}
}
                
@article{
10.1111:cgf.12498,
journal = {Computer Graphics Forum}, title = {{
Learning Natural Colors for Image Recoloring}},
author = {
Huang, Hao-Zhi
and
Zhang, Song-Hai
and
Martin, Ralph R.
and
Hu, Shi-Min
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12498}
}
                
@article{
10.1111:cgf.12499,
journal = {Computer Graphics Forum}, title = {{
Perceptually-based Color Assignment}},
author = {
Kim, Hye-Rin
and
Yoo, Min-Joon
and
Kang, Henry
and
Lee, In-Kwon
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12499}
}
                
@article{
10.1111:cgf.12500,
journal = {Computer Graphics Forum}, title = {{
Illuminant Aware Gamut-Based Color Transfer}},
author = {
Nguyen, Rang M. H.
and
Kim, Seon Joo
and
Brown, Michael S.
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12500}
}
                
@article{
10.1111:cgf.12501,
journal = {Computer Graphics Forum}, title = {{
Single-shot High Dynamic Range Imaging Using Coded Electronic Shutter}},
author = {
Cho, Hojin
and
Kim, Seon Joo
and
Lee, Seungyong
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12501}
}
                
@article{
10.1111:cgf.12502,
journal = {Computer Graphics Forum}, title = {{
Fast Feature-Oriented Visual Connection for Large Image Collections}},
author = {
Yan, Qingan
and
Xu, Zhan
and
Xiao, Chunxia
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12502}
}
                
@article{
10.1111:cgf.12503,
journal = {Computer Graphics Forum}, title = {{
Perceptually-motivated Stereoscopic Film Grain}},
author = {
Templin, Krzysztof
and
Didyk, Piotr
and
Myszkowski, Karol
and
Seidel, Hans-Peter
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12503}
}
                
@article{
10.1111:cgf.12504,
journal = {Computer Graphics Forum}, title = {{
Time-Lapse Photometric Stereo and Applications}},
author = {
Shen, Fangyang
and
Sunkavalli, Kalyan
and
Bonneel, Nicolas
and
Rusinkiewicz, Szymon
and
Pfister, Hanspeter
and
Tong, Xin
}, year = {
2014},
publisher = {
The Eurographics Association and John Wiley and Sons Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/cgf.12504}
}

Browse

Recent Submissions

Now showing 1 - 38 of 38
  • Item
    Preface and Table of Contents
    (The Eurographics Association and Blackwell Publishing Ltd., 2014) J. Keyser, Y. J. Kim, and P. Wonka
  • Item
    Environment-Adaptive Contact Poses for Virtual Characters
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Kang, Changgu; Lee, Sung-Hee; J. Keyser, Y. J. Kim, and P. Wonka
    We present a novel method to generate a virtual character's multi-contact poses adaptive to the various shapes of the environment. Given the user-specified center of mass (CoM) position and direction as inputs, our method finds the potential contacts for the character in the surrounding geometry of the environment and generates a set of stable poses that are contact-rich. Major contributions of the work are in efficiently finding admissible support points for the target environment by precomputing candidate support points from a human pose database, and in automatically generating interactive poses that can maintain stable equilibrium. We develop the concept of support complexity to scale the set of precomputed support points by the geometric complexity of the environment. We demonstrate the effectiveness of our method by creating contact poses for various test cases of environments.
  • Item
    Data-Driven Reconstruction of Human Locomotion Using a Single Smartphone
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Eom, Haegwang; Choi, Byungkuk; Noh, Junyong; J. Keyser, Y. J. Kim, and P. Wonka
    Generating a visually appealing human motion sequence using low-dimensional control signals is a major line of study in the motion research area in computer graphics. We propose a novel approach that allows us to reconstruct full body human locomotion using a single inertial sensing device, a smartphone. Smartphones are among the most widely used devices and incorporate inertial sensors such as an accelerometer and a gyroscope. To find a mapping between a full body pose and smartphone sensor data, we perform low dimensional embedding of full body motion capture data, based on a Gaussian Process Latent Variable Model. Our system ensures temporal coherence between the reconstructed poses by using a state decomposition model for automatic phase segmentation. Finally, application of the proposed nonlinear regression algorithm finds a proper mapping between the latent space and the sensor data. Our framework effectively reconstructs plausible 3D locomotion sequences. We compare the generated animation to ground truth data obtained using a commercial motion capture system.
  • Item
    Editing and Synthesizing Two-Character Motions using a Coupled Inverted Pendulum Model
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Hwang, Jaepyung; Suh, Il Hong; Kwon, Taesoo; J. Keyser, Y. J. Kim, and P. Wonka
    This study aims to develop a controller for use in the online simulation of two interacting characters. This controller is capable of generalizing two sets of interaction motions of the two characters based on the relationships between the characters. The controller can exhibit similar motions to a captured human motion while reacting in a natural way to the opponent character in real time. To achieve this, we propose a new type of physical model called a coupled inverted pendulum on carts that comprises two inverted pendulum on a cart models, one for each individual, which are coupled by a relationship model. The proposed framework is divided into two steps: motion analysis and motion synthesis. Motion analysis is an offline preprocessing step, which optimizes the control parameters to move the proposed model along a motion capture trajectory of two interacting humans. The optimization procedure generates a coupled pendulum trajectory which represents the relationship between two characters for each frame, and is used as a reference in the synthesis step. In the motion synthesis step, a new coupled pendulum trajectory is planned reflecting the effects of the physical interaction, and the captured reference motions are edited based on the planned trajectory produced by the coupled pendulum trajectory generator. To validate the proposed framework, we used a motion capture data set showing two people performing kickboxing. The proposed controller is able to generalize the behaviors of two humans to different situations such as different speeds and turning speeds in a realistic way in real time.
  • Item
    Locomotion Skills for Insects with Sample-based Controller
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Guo, Shihui; Chang, Jian; Yang, Xiaosong; Wang, Wencheng; Zhang, Jianjun; J. Keyser, Y. J. Kim, and P. Wonka
    Natural-looking insect animation is very difficult to simulate. The fast movement and small scale of insects often challenge the standard motion capture techniques. As for the manual key-framing or physics-driven methods, significant amounts of time and efforts are necessary due to the delicate structure of the insect, which prevents practical applications. In this paper, we address this challenge by presenting a two-level control framework to efficiently automate the modeling and authoring of insects' locomotion. On the top level, we design a Triangle Placement Engine to automatically determine the location and orientation of insects' foot contacts, given the userdefined trajectory and settings, including speed, load, path and terrain etc. On the low-level, we relate the Central Pattern Generator to the triangle profiles with the assistance of a Controller Look-Up Table to fast simulate the physically-based movement of insects. With our approach, animators can directly author insects' behavior among a wide range of locomotion repertoire, including walking along a specified path or on an uneven terrain, dynamically adjusting to external perturbations and collectively transporting prey back to the nest.
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    A Data-Driven Framework for Visual Crowd Analysis
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Charalambous, Panayiotis; Karamouzas, Ioannis; Guy, Stephen J.; Chrysanthou, Yiorgos; J. Keyser, Y. J. Kim, and P. Wonka
    We present a novel approach for analyzing the quality of multi-agent crowd simulation algorithms. Our approach is data-driven, taking as input a set of user-defined metrics and reference training data, either synthetic or from video footage of real crowds. Given a simulation, we formulate the crowd analysis problem as an anomaly detection problem and exploit state-of-the-art outlier detection algorithms to address it. To that end, we introduce a new framework for the visual analysis of crowd simulations. Our framework allows us to capture potentially erroneous behaviors on a per-agent basis either by automatically detecting outliers based on individual evaluation metrics or by accounting for multiple evaluation criteria in a principled fashion using Principle Component Analysis and the notion of Pareto Optimality. We discuss optimizations necessary to allow real-time performance on large datasets and demonstrate the applicability of our framework through the analysis of simulations created by several widely-used methods, including a simulation from a commercial game.
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    shade.js: Adaptive Material Descriptions
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Sons, Kristian; Klein, Felix; Sutter, Jan; Slusallek, Philipp; J. Keyser, Y. J. Kim, and P. Wonka
    In computer graphics a material is a visual concept that is parameterizable and should work for arbitrary 3D assets and rendering systems. Since provided parameters and attributes as well as the capabilities of rendering systems vary considerably, a material needs to adapt to its execution environment. In current approaches, the adaptation logic is 'baked' into the rendering application based on string manipulation, compiler directives, or metaprogramming facilities. However, in order to achieve application-independent and self-contained material descriptions, the adaptation logic needs to be part of the material description itself. In this paper we present shade.js, a novel material description using a dynamic language to achieve the necessary adaptivity. A shader can inspect its execution environment and adapt to the available parameters and renderer capabilities at run time. Additionally, shade.js exploits the polymorphism that comes with non-explicit declaration of types. These two novel features allow for writing adaptable and thus more general material descriptions. Based on the concrete execution environment at run time, the accompanied compiler generates specialized shader code that is specifically typed and optimized for the target rendering system and algorithm. We evaluate shade.js with examples targeting four different rendering approaches (forward and deferred rasterization, ray-tracing, and global illumination). We show that we can improve convenience and flexibility for specifying materials without sacrificing performance.
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    Using Physically Based Rendering to Benchmark Structured Light Scanners
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Medeiros, Esdras; Doraiswamy, Harish; Berger, Matthew; Silva, Claudio T.; J. Keyser, Y. J. Kim, and P. Wonka
    Structured light scanning is ubiquituous in 3D acquisition. It is capable of capturing high geometric detail at a low cost under a variety of challenging scene conditions. Recent methods have demonstrated robustness in the presence of artifacts due to global illumination, such as inter-reflections and sub-surface scattering, as well as imperfections caused by projector defocus. For comparing approaches, however, the quantitative evaluation of structured lighting schemes is hindered by the challenges in obtaining ground truth data, resulting in a poor understanding for these methods across a wide range of shapes, materials, and lighting configurations. In this paper, we present a benchmark to study the performance of structured lighting algorithms in the presence of errors caused due to the above properties of the scene. In order to do this, we construct a synthetic structured lighting scanner that uses advanced physically based rendering techniques to simulate the point cloud acquisition process. We show that, under conditions similar to that of a real scanner, our synthetic scanner replicates the same artifacts found in the output of a real scanner. Using this synthetic scanner, we perform a quantitative evaluation of four different structured lighting techniques - gray-code patterns, micro-phase shifting, ensemble codes, and unstructured light scanning. The evaluation, performed on a variety of scenes,demonstrate that no one method is capable of adequately handling all sources of error - each method is appropriate for addressing distinct sources of error.
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    Sky Based Light Metering for High Dynamic Range Images
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Gryaditskya, Yulia; Pouli, Tania; Reinhard, Erik; Seidel, Hans-Peter; J. Keyser, Y. J. Kim, and P. Wonka
    Image calibration requires both linearization of pixel values and scaling so that values in the image correspond to real-world luminances. In this paper we focus on the latter and rather than rely on camera characterization, we calibrate images by analysing their content and metadata, obviating the need for expensive measuring devices or modeling of lens and camera combinations. Our analysis correlates sky pixel values to luminances that would be expected based on geographical metadata. Combined with high dynamic range (HDR) imaging, which gives us linear pixel data, our algorithm allows us to find absolute luminance values for each pixel-effectively turning digital cameras into absolute light meters. To validate our algorithm we have collected and annotated a calibrated set of HDR images and compared our estimation with several other approaches, showing that our approach is able to more accurately recover absolute luminance. We discuss various applications and demonstrate the utility of our method in the context of calibrated color appearance reproduction and lighting design.
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    Sub-Pixel Anti-Aliasing Via Triangle-Based Geometry Reconstruction
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Du, Wenjun; Feng, Jieqing; Yang, Baoguang; J. Keyser, Y. J. Kim, and P. Wonka
    Anti-aliasing has recently been employed as a post-processing step to adapt to the deferred shading technique in real-time applications. Some of these existing algorithms store supersampling geometric information as geometric buffer (G-buffer) to detect and alleviate sub-pixel-level aliasing artifacts. However, the anti-aliasing filter based on sampled sub-pixel geometries only may introduce unfaithful shading information to the sub-pixel color in uniform-geometry regions, and large G-buffer will increase memory storage and fetch overheads. In this paper, we present a new Triangle-based Geometry Anti-Aliasing (TGAA) algorithm, to address these problems. The coverage triangle of each screen pixel is accessed, and then, the coverage information between the triangle and neighboring sub-pixels is stored in a screen-resolution bitmask, which allows the geometric information to be stored and accessed in an inexpensive manner. Using triangle-based geometry, TGAA can exclude irrelevant neighboring shading samples and achieve faithful anti-aliasing filtering. In addition, a morphological method of estimating the geometric edges in high-frequency geometry is incorporated into the TGAA's anti-aliasing filter to complement the algorithm. The implementation results demonstrate that the algorithm is efficient and scalable for generating high-quality anti-aliased images.
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    Template-Based Sampling of Anisotropic BRDFs
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Filip, Jiri; Vávra, Radomir; J. Keyser, Y. J. Kim, and P. Wonka
    BRDFs are commonly used to represent given materials' appearance in computer graphics and related fields. Although, in the recent past, BRDFs have been extensively measured, compressed, and fitted by a variety of ana- lytical models, most research has been primarily focused on simplified isotropic BRDFs. In this paper, we present a unique database of 150 BRDFs representing a wide range of materials; the majority exhibiting anisotropic be- havior. Since time-consuming BRDF measurement represents a major obstacle in the digital material appearance reproduction pipeline, we tested several approaches estimating a very limited set of samples capable of high quality appearance reconstruction. Initially, we aligned all measured BRDFs according to the location of the anisotropic highlights. Then we propose an adaptive sampling method based on analysis of the measured BRDFs. For each BRDF, a unique sampling pattern was computed, given a predefined count of samples. Further, template-based methods are introduced based on reusing of the precomputed sampling patterns. This approach enables a more efficient measurement of unknown BRDFs while preserving the visual fidelity for the majority of tested materials. Our method exhibits better performance and stability than competing sparse sampling approaches; especially for higher numbers of samples.
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    Interactive Image-Guided Modeling of Extruded Shapes
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Cao, Yan-Pei; Ju, Tao; Fu, Zhao; Hu, Shi-Min; J. Keyser, Y. J. Kim, and P. Wonka
    A recent trend in interactive modeling of 3D shapes from a single image is designing minimal interfaces, and accompanying algorithms, for modeling a specific class of objects. Expanding upon the range of shapes that existing minimal interfaces can model, we present an interactive image-guided tool for modeling shapes made up of extruded parts. An extruded part is represented by extruding a closed planar curve, called base, in the direction orthogonal to the base. To model each extruded part, the user only needs to sketch the projected base shape in the image. The main technical contribution is a novel optimization-based approach for recovering the 3D normal of the base of an extruded object by exploring both geometric regularity of the sketched curve and image contents. We developed a convenient interface for modeling multi-part shapes and a method for optimizing the relative placement of the parts. Our tool is validated using synthetic data and tested on real-world images.
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    Anisotropic Geodesics for Live-wire Mesh Segmentation
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Zhuang, Yixin; Zou, Ming; Carr, Nathan; Ju, Tao; J. Keyser, Y. J. Kim, and P. Wonka
    We present an interactive method for mesh segmentation that is inspired by the classical live-wire interaction for image segmentation. The core contribution of the work is the definition and computation of wires on surfaces that are likely to lie at segment boundaries. We define wires as geodesics in a new tensor-based anisotropic metric, which improves upon previous metrics in stability and feature-awareness. We further introduce a simple but effective mesh embedding approach that allows geodesic paths in an anisotropic path to be computed efficiently using existing algorithms designed for Euclidean geodesics. Our tool is particularly suited for delineating segmentation boundaries that are aligned with features or curvature directions, and we demonstrate its use in creating artist-guided segmentations.
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    Multiple Shape Correspondence by Dynamic Programming
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Sahillioglu, Yusuf; Yemez, Yucel; J. Keyser, Y. J. Kim, and P. Wonka
    We present a multiple shape correspondence method based on dynamic programming, that computes consistent bijective maps between all shape pairs in a given collection of initially unmatched shapes. As a fundamental distinction from previous work, our method aims to explicitly minimize the overall distortion, i.e., the average isometric distortion of the resulting maps over all shape pairs. We cast the problem as optimal path finding on a graph structure where vertices are maps between shape extremities. We exploit as much context information as possible using a dynamic programming based algorithm to approximate the optimal solution. Our method generates coarse multiple correspondences between shape extremities, as well as denser correspondences as byproduct. We assess the performance on various mesh sequences of (nearly) isometric shapes. Our experiments show that, for isometric shape collections with non-uniform triangulation and noise, our method can compute relatively dense correspondences reasonably fast and outperform state of the art in terms of accuracy.
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    Approximate Symmetry Detection in Partial 3D Meshes
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Sipiran, Ivan; Gregor, Robert; Schreck, Tobias; J. Keyser, Y. J. Kim, and P. Wonka
    Symmetry is a common characteristic in natural and man-made objects. Its ubiquitous nature can be exploited to facilitate the analysis and processing of computational representations of real objects. In particular, in computer graphics, the detection of symmetries in 3D geometry has enabled a number of applications in modeling and reconstruction. However, the problem of symmetry detection in incomplete geometry remains a challenging task. In this paper, we propose a vote-based approach to detect symmetry in 3D shapes, with special interest in models with large missing parts. Our algorithm generates a set of candidate symmetries by matching local maxima of a surface function based on the heat diffusion in local domains, which guarantee robustness to missing data. In order to deal with local perturbations, we propose a multi-scale surface function that is useful to select a set of distinctive points over which the approximate symmetries are defined. In addition, we introduce a vote-based scheme that is aware of the partiality, and therefore reduces the number of false positive votes for the candidate symmetries. We show the effectiveness of our method in a varied set of 3D shapes and different levels of partiality. Furthermore, we show the applicability of our algorithm in the repair and completion of challenging reassembled objects in the context of cultural heritage.
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    Structure Aware Visual Cryptography
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Liu, Bin; Martin, Ralph R.; Huang, Ji-Wu; Hu, Shi-Min; J. Keyser, Y. J. Kim, and P. Wonka
    Visual cryptography is an encryption technique that hides a secret image by distributing it between some shared images made up of seemingly random black-and-white pixels. Extended visual cryptography (EVC) goes further in that the shared images instead represent meaningful binary pictures. The original approach to EVC suffered from low contrast, so later papers considered how to improve the visual quality of the results by enhancing contrast of the shared images. This work further improves the appearance of the shared images by preserving edge structures within them using a framework of dithering followed by a detail recovery operation.We are also careful to suppress noise in smooth areas.
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    G2 Surface Interpolation Over General Topology Curve Networks
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Salvi, Péter; Várady, Tamás; J. Keyser, Y. J. Kim, and P. Wonka
    The basic idea of curve network-based design is to construct smoothly connected surface patches, that interpolate boundaries and cross-derivatives extracted from the curve network. While the majority of applications demands only tangent plane (G1) continuity between the adjacent patches, curvature continuous connections (G2) may also be required. Examples include special curve network configurations with supplemented internal edges, ''masterslave'' curvature constraints, and general topology surface approximations over meshes. The first step is to assign optimal surface curvatures to the nodes of the curve network; we discuss different optimization procedures for various types of nodes. Then interpolant surfaces called parabolic ribbons are created along the patch boundaries, which carry first and second derivative constraints. Our construction guarantees that the neighboring ribbons, and thus the respective transfinite patches, will be G2 continuous. We extend Gregory's multi-sided surface scheme in order to handle parabolic ribbons, involving the blending functions, and a new sweepline parameterization. A few simple examples conclude the paper.
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    Polyline-sourced Geodesic Voronoi Diagrams on Triangle Meshes
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Xu, Chunxu; Liu, Yong-Jin; Sun, Qian; Li, Jinyan; He, Ying; J. Keyser, Y. J. Kim, and P. Wonka
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    Fast and Scalable Mesh Superfacets
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Simari, Patricio; Picciau, Giulia; Floriani, Leila De; J. Keyser, Y. J. Kim, and P. Wonka
    In the field of computer vision, the introduction of a low-level preprocessing step to oversegment images into superpixels - relatively small regions whose boundaries agree with those of the semantic entities in the scene - has enabled advances in segmentation by reducing the number of elements to be labeled from hundreds of thousands, or millions, to a just few hundred. While some recent works in mesh processing have used an analogous oversegmentation, they were not intended to be general and have relied on graph cut techniques that do not scale to current mesh sizes. Here, we present an iterative superfacet algorithm and introduce adaptations of undersegmentation error and compactness, which are well-motivated and principled metrics from the vision community. We demonstrate that our approach produces results comparable to those of the normalized cuts algorithm when evaluated on the Princeton Segmentation Benchmark, while requiring orders of magnitude less time and memory and easily scaling to, and enabling the processing of, much larger meshes.
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    Adaptive Multi-scale Analysis for Point-based Surface Editing
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Nader, Georges; Guennebaud, Gael; Mellado, Nicolas; J. Keyser, Y. J. Kim, and P. Wonka
    This paper presents a tool that enables the direct editing of surface features in large point-clouds or meshes. This is made possible by a novel multi-scale analysis of unstructured point-clouds that automatically extracts the number of relevant features together with their respective scale all over the surface. Then, combining this ingredient with an adequate multi-scale decomposition allows us to directly enhance or reduce each feature in an independent manner. Our feature extraction is based on the analysis of the scale-variations of locally fitted surface primitives combined with unsupervised learning techniques. Our tool may be applied either globally or locally, and millions of points are handled in real-time. The resulting system enables users to accurately edit complex geometries with minimal interaction.
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    Fractional Reyes-Style Adaptive Tessellation for Continuous Level of Detail
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Liktor, Gabor; Pan, Minghao; Dachsbacher, Carsten; J. Keyser, Y. J. Kim, and P. Wonka
    In this paper we present a fractional parametric splitting scheme for Reyes-style adaptive tessellation. Our parallel algorithm generates crack-free tessellation from a parametric surface, which is also free of sudden temporal changes under animation. Continuous level of detail is not addressed by existing Reyes-style methods, since these aim to produce subpixel-sized micropolygons, where topology changes are no longer noticeable. Using our method, rendering pipelines that use larger triangles, thus sensitive to geometric popping, may also benefit from the quality of the split-dice tessellation stages of Reyes. We demonstrate results on a real-time GPU implementation, going beyond the limited quality and resolution of the hardware tessellation unit. In contrast to previous split-dice methods, our split stage is compatible with the fractional hardware tessellation scheme that has been designed for continuous level of detail.
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    Hybrid Particle-grid Modeling for Multi-scale Droplet/Spray Simulation
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Yang, Lipeng; Li, Shuai; Hao, Aimin; Qin, Hong; J. Keyser, Y. J. Kim, and P. Wonka
    This paper presents a novel hybrid particle-grid method that tightly couples Lagrangian particle approach with Eulerian grid approach to simulate multi-scale diffuse materials varying from disperse droplets to dissipating spray and their natural mixture and transition, originated from a violent (high-speed) liquid stream. Despite the fact that Lagrangian particles are widely employed for representing individual droplets and Eulerian grid-based method is ideal for volumetric spray modeling, using either one alone has encountered tremendous difficulties when effectively simulating droplet/spray mixture phenomena with high fidelity. To ameliorate, we propose a new hybrid model to tackle such challenges with many novel technical elements. At the geometric level, we employ the particle and density field to represent droplet and spray respectively, modeling their creation from liquid as well as their seamless transition. At the physical level, we introduce a drag force model to couple droplets and spray, and specifically, we employ Eulerian method to model the interaction among droplets and marry it with the widelyused Lagrangian model. Moreover, we implement our entire hybrid model on CUDA to guarantee the interactive performance for high-effective physics-based graphics applications. The comprehensive experiments have shown that our hybrid approach takes advantages of both particle and grid methods, with convincing graphics effects for disperse droplets and spray simulation.
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    Advanced Hybrid Particle-Grid Method with Sub-Grid Particle Correction
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Um, Kiwon; Baek, Seungho; Han, JungHyun; J. Keyser, Y. J. Kim, and P. Wonka
    This paper proposes a novel hybrid particle-grid approach to liquid simulation, which uses the fluid-implicitparticle (FLIP) method to resolve the liquid motion and a grid-based particle correction method to complement FLIP. The correction process addresses the high-frequency errors in FLIP ensuring that the particles are properly distributed. The proposed approach enables the corrective procedure to avoid directly processing the particle relationships and supports flexible corrective forces. The proposed technique effectively and efficiently improves the distribution of the particles and therefore enhances the overall simulation quality. The experimental results confirm that the technique is able to conserve the liquid volume and to produce dynamic surface motions, thin liquid sheets, and smooth surfaces without disturbing artifacts such as bumpy noise.
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    Incompressible SPH using the Divergence-Free Condition
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Kang, Nahyup; Sagong, Donghoon; J. Keyser, Y. J. Kim, and P. Wonka
    In this paper, we present a novel SPH framework to simulate incompressible fluid that satisfies both the divergencefree condition and the density-invariant condition. In our framework, the two conditions are applied separately. First, the divergence-free condition is enforced when solving the momentum equation. Later, the density-invariant condition is applied after the time integration of the particle positions. Our framework is a purely Lagrangian approach so that no auxiliary grid is required. Compared to the previous density-invariant based SPH methods, the proposed method is more accurate due to the explicit satisfaction of the divergence-free condition. We also propose a modified boundary particle method for handling the free-slip condition. In addition, two simple but effective methods are proposed to reduce the particle clumping artifact induced by the density-invariant condition.
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    Real-Time Symmetry-Preserving Deformation
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Wu, Xiaokun; Wand, Michael; Hildebrandt, Klaus; Kohli, Pushmeet; Seidel, Hans-Peter; J. Keyser, Y. J. Kim, and P. Wonka
    In this paper, we address the problem of structure-aware shape deformation: We specifically consider deformations that preserve symmetries of the shape being edited. While this is an elegant approach for obtaining plausible shape variations from minimal assumptions, a straightforward optimization is numerically expensive and poorly conditioned. Our paper introduces an explicit construction of bases of linear spaces of shape deformations that exactly preserve symmetries for any user-defined level of detail. This permits the construction of low-dimensional spaces of low-frequency deformations that preserve the symmetries. We obtain substantial speed-ups over alternative approaches for symmetry-preserving shape editing due to (i) the sub-space approach, which permits low-res editing, (ii) the removal of redundant, symmetric information, and (iii) the simplification of the numerical formulation due to hard-coded symmetry preservation. We demonstrate the utility in practice by applying our framework to symmetry-preserving co-rotated iterative Laplace surface editing of models with complex symmetry structure, including partial and nested symmetry.
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    Sparse Localized Decomposition of Deformation Gradients
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Huang, Zhichao; Yao, Junfeng; Zhong, Zichun; Liu, Yang; Guo, Xiaohu; J. Keyser, Y. J. Kim, and P. Wonka
    Sparse localized decomposition is a useful technique to extract meaningful deformation components out of a training set of mesh data. However, existing methods cannot capture large rotational motion in the given mesh dataset. In this paper we present a new decomposition technique based on deformation gradients. Given a mesh dataset, the deformation gradient field is extracted, and decomposed into two groups: rotation field and stretching field, through polar decomposition. These two groups of deformation information are further processed through the sparse localized decomposition into the desired components. These sparse localized components can be linearly combined to form a meaningful deformation gradient field, and can be used to reconstruct the mesh through a least squares optimization step. Our experiments show that the proposed method addresses the rotation problem associated with traditional deformation decomposition techniques, making it suitable to handle not only stretched deformations, but also articulated motions that involve large rotations.
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    2D-3D Lifting for Shape Reconstruction
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Nan, Liangliang; Sharf, Andrei; Chen, Baoquan; J. Keyser, Y. J. Kim, and P. Wonka
    We present an algorithm for shape reconstruction from incomplete 3D scans by fusing together two acquisition modes: 2D photographs and 3D scans. The two modes exhibit complementary characteristics: scans have depth information, but are often sparse and incomplete; photographs, on the other hand, are dense and have high resolution, but lack important depth information. In this work we fuse the two modes, taking advantage of their complementary information, to enhance 3D shape reconstruction from an incomplete scan with a 2D photograph. We compute geometrical and topological shape properties in 2D photographs and use them to reconstruct a shape from an incomplete 3D scan in a principled manner. Our key observation is that shape properties such as boundaries, smooth patches and local connectivity, can be inferred with high confidence from 2D photographs. Thus, we register the 3D scan with the 2D photograph and use scanned points as 3D depth cues for lifting 2D shape structures into 3D. Our contribution is an algorithm which significantly regularizes and enhances the problem of 3D reconstruction from partial scans by lifting 2D shape structures into 3D. We evaluate our algorithm on various shapes which are loosely scanned and photographed from different views, and compare them with state-of-the-art reconstruction methods.
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    Realistic Road Path Reconstruction from GIS Data
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Nguyen, Hoang Ha; Desbenoit, Brett; Daniel, Marc; J. Keyser, Y. J. Kim, and P. Wonka
    We introduce a new approach to construct smooth piecewise curves representing realistic road paths. Given a GIS database of road networks in which sampled points are organized in 3D polylines, our method creates horizontal, then vertical curves, and finally combines them to produce 3D road paths. We first estimate the possibility of each point of being a junction between two separate primitive curve segments. Next, we design a tree-traversal algorithm to expand sequences of local best fit primitives which are then merged together with respect to the G1 continuity constraint and civil engineering rules. We apply the Levenberg-Marquardt method to minimize the error between the resulting curve and the sampled points while preserving the G1 continuity.
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    Efficient Depth Propagation for Constructing a Layered Depth Image from a Single Image
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Iizuka, Satoshi; Endo, Yuki; Kanamori, Yoshihiro; Mitani, Jun; Fukui, Yukio; J. Keyser, Y. J. Kim, and P. Wonka
    In this paper, we propose an interactive technique for constructing a 3D scene via sparse user inputs. We represent a 3D scene in the form of a Layered Depth Image (LDI) which is composed of a foreground layer and a background layer, and each layer has a corresponding texture and depth map. Given user-specified sparse depth inputs, depth maps are computed based on superpixels using interpolation with geodesic-distance weighting and an optimization framework. This computation is done immediately, which allows the user to edit the LDI interactively. Additionally, our technique automatically estimates depth and texture in occluded regions using the depth discontinuity. In our interface, the user paints strokes on the 3D model directly. The drawn strokes serve as 3D handles with which the user can pull out or push the 3D surface easily and intuitively with real-time feedback. We show our technique enables efficient modeling of LDI that produce sufficient 3D effects.
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    Automatic 3D Indoor Scene Updating with RGBD Cameras
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Liu, Zhenbao; Tang, Sicong; Xu, Weiwei; Bu, Shuhui; Han, Junwei; Zhou, Kun; J. Keyser, Y. J. Kim, and P. Wonka
    Since indoor scenes are frequently changed in daily life, such as re-layout of furniture, the 3D reconstructions for them should be flexible and easy to update. We present an automatic 3D scene update algorithm to indoor scenes by capturing scene variation with RGBD cameras. We assume an initial scene has been reconstructed in advance in manual or other semi-automatic way before the change, and automatically update the reconstruction according to the newly captured RGBD images of the real scene update. It starts with an automatic segmentation process without manual interaction, which benefits from accurate labeling training from the initial 3D scene. After the segmentation, objects captured by RGBD camera are extracted to form a local updated scene. We formulate an optimization problem to compare to the initial scene to locate moved objects. The moved objects are then integrated with static objects in the initial scene to generate a new 3D scene. We demonstrate the efficiency and robustness of our approach by updating the 3D scene of several real-world scenes.
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    Making in-Front-of Cars Transparent: Sharing First-Person-Views via Dashcam
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Chen, Shao-Chi; Chen, Hsin-Yi; Chen, Yi-Ling; Tsai, Hsin-Mu; Chen, Bing-Yu; J. Keyser, Y. J. Kim, and P. Wonka
    Visual obstruction caused by a preceding vehicle is one of the key factors threatening driving safety. One possible solution is to share the first-person-view of the preceding vehicle to unveil the blocked field-of-view of the following vehicle. However, the geometric inconsistency caused by the camera-eye discrepancy renders view sharing between different cars a very challenging task. In this paper, we present a first-person-perspective image rendering algorithm to solve this problem. Firstly, we contour unobstructed view as the transferred region, then by iteratively estimating local homography transformations and performing perspective-adaptive warping using the estimated transformations, we are able to locally adjust the shape of the unobstructed view so that its perspective and boundary could be matched to that of the occluded region. Thus, the composited view is seamless in both the perceived perspective and photometric appearance, creating an impression as if the preceding vehicle is transparent. Our system improves the driver's visibility and thus relieves the burden on the driver, which in turn increases comfort. We demonstrate the usability and stability of our system by performing its evaluation with several challenging data sets collected from real-world driving scenarios.
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    Learning Natural Colors for Image Recoloring
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Huang, Hao-Zhi; Zhang, Song-Hai; Martin, Ralph R.; Hu, Shi-Min; J. Keyser, Y. J. Kim, and P. Wonka
    We present a data-driven method for automatically recoloring a photo to enhance its appearance or change a viewer's emotional response to it. A compact representation called a RegionNet summarizes color and geometric features of image regions, and geometric relationships between them. Correlations between color property distributions and geometric features of regions are learned from a database of well-colored photos. A probabilistic factor graph model is used to summarize distributions of color properties and generate an overall probability distribution for color suggestions. Given a new input image, we can generate multiple recolored results which unlike previous automatic results, are both natural and artistic, and compatible with their spatial arrangements.
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    Perceptually-based Color Assignment
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Kim, Hye-Rin; Yoo, Min-Joon; Kang, Henry; Lee, In-Kwon; J. Keyser, Y. J. Kim, and P. Wonka
    Color assignment is a complex task of incorporating and balancing area configuration, color harmony, and user's intent. In this paper, we present a novel method for automatic color assignment based on theories of color perception. We define color assignment as an optimization problem with respect to the color relationships as well as the spatial configuration of input segments. We also suggest possible constraints that are suitable for taskspecific purposes and for enhancing visual appeal. Our colorization scheme is useful in many applications such as infographics, computer-aided design, and visual presentation. The user study shows that our method generates perceptually pleasing results over a variety of data sets.
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    Illuminant Aware Gamut-Based Color Transfer
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Nguyen, Rang M. H.; Kim, Seon Joo; Brown, Michael S.; J. Keyser, Y. J. Kim, and P. Wonka
    This paper proposes a new approach for color transfer between two images. Our method is unique in its consideration of the scene illumination and the constraint that the mapped image must be within the color gamut of the target image. Specifically, our approach first performs a white-balance step on both images to remove color casts caused by different illuminations in the source and target image. We then align each image to share the same 'white axis' and perform a gradient preserving histogram matching technique along this axis to match the tone distribution between the two images. We show that this illuminant-aware strategy gives a better result than directly working with the original source and target image's luminance channel as done by many previous methods. Afterwards, our method performs a full gamut-based mapping technique rather than processing each channel separately. This guarantees that the colors of our transferred image lie within the target gamut. Our experimental results show that this combined illuminant-aware and gamut-based strategy produces more compelling results than previous methods. We detail our approach and demonstrate its effectiveness on a number of examples.
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    Single-shot High Dynamic Range Imaging Using Coded Electronic Shutter
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Cho, Hojin; Kim, Seon Joo; Lee, Seungyong; J. Keyser, Y. J. Kim, and P. Wonka
    Typical high dynamic range (HDR) imaging approaches based on multiple images have difficulties in handling moving objects and camera shakes, suffering from the ghosting effect and the loss of sharpness in the output HDR image. While there exist a variety of solutions for resolving such limitations, most of the existing algorithms are susceptible to complex motions, saturation, and occlusions. In this paper, we propose an HDR imaging approach using the coded electronic shutter which can capture a scene with row-wise varying exposures in a single image. Our approach enables a direct extension of the dynamic range of the captured image without using multiple images, by photometrically calibrating rows with different exposures. Due to the concurrent capture of multiple exposures, misalignments of moving objects are naturally avoided with significant reduction in the ghosting effect. To handle the issues with under-/over-exposure, noise, and blurs, we present a coherent HDR imaging process where the problems are resolved one by one at each step. Experimental results with real photographs, captured using a coded electronic shutter, demonstrate that our method produces a high quality HDR images without the ghosting and blur artifacts.
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    Fast Feature-Oriented Visual Connection for Large Image Collections
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Yan, Qingan; Xu, Zhan; Xiao, Chunxia; J. Keyser, Y. J. Kim, and P. Wonka
    Deriving the visual connectivity across large image collections is a computationally expensive task. Different from current image-oriented match graph construction methods which build on pairwise image matching, we present a novel and scalable feature-oriented image matching algorithm for large collections. Our method improves the match graph construction procedure in three ways. First, instead of building trees repeatedly, we put the feature points of the input image collection into a single kd-tree and select the leaves as our anchor points. Then we construct an anchor graph from which each feature can intelligently find a small portion of related candidates to match. Finally, we design a new form of adjacency matrix for fast feature similarity measuring, and return all the matches in different photos across the whole dataset directly. Experiments show that our feature-oriented correspondence algorithm can explore visual connectivity between images with significant improvement in speed.
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    Perceptually-motivated Stereoscopic Film Grain
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Templin, Krzysztof; Didyk, Piotr; Myszkowski, Karol; Seidel, Hans-Peter; J. Keyser, Y. J. Kim, and P. Wonka
    Independent management of film grain in each view of a stereoscopic video can lead to visual discomfort. The existing alternative is to project the grain onto the scene geometry. Such grain, however, looks unnatural, changes object perception, and emphasizes inaccuracies in depth arising during 2D-to-3D conversion. We propose an advanced method of grain positioning that scatters the grain in the scene space. In a series of perceptual experiments, we estimate the optimal parameter values for the proposed method, analyze the user preference distribution among the proposed and the two existing methods, and show influence of the method on the object perception.
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    Time-Lapse Photometric Stereo and Applications
    (The Eurographics Association and John Wiley and Sons Ltd., 2014) Shen, Fangyang; Sunkavalli, Kalyan; Bonneel, Nicolas; Rusinkiewicz, Szymon; Pfister, Hanspeter; Tong, Xin; J. Keyser, Y. J. Kim, and P. Wonka
    This paper presents a technique to recover geometry from time-lapse sequences of outdoor scenes. We build upon photometric stereo techniques to recover approximate shadowing, shading and normal components allowing us to alter the material and normals of the scene. Previous work in analyzing such images has faced two fundamental difficulties: 1. the illumination in outdoor images consists of time-varying sunlight and skylight, and 2. the motion of the sun is restricted to a near-planar arc through the sky, making surface normal recovery unstable. We develop methods to estimate the reflection component due to skylight illumination. We also show that sunlight directions are usually non-planar, thus making surface normal recovery possible. This allows us to estimate approximate surface normals for outdoor scenes using a single day of data. We demonstrate the use of these surface normals for a number of image editing applications including reflectance, lighting, and normal editing.