30-Issue 8

Permanent URI for this collection


Table of Contents


Simplex and Diamond Hierarchies: Models and Applications

Weiss, K.
Floriani, L. De

Learning Boundary Edges for 3D‐Mesh Segmentation

Benhabiles, Halim
Lavoué, Guillaume
Vandeborre, Jean‐Philippe
Daoudi, Mohamed

Non‐Linear Beam Tracing on a GPU

Liu, Baoquan
Wei, Li‐Yi
Yang, Xu
Ma, Chongyang
Xu, Ying‐Qing
Guo, Baining
Wu, Enhua

Finding Syntactic Structures from Human Motion Data

Park, Jong Pil
Lee, Kang Hoon
Lee, Jehee

Stroke Correspondence Construction Using Manifold Learning

Liu, Dongquan
Chen, Quan
Yu, Jun
Gu, Huiqin
Tao, Dacheng
Seah, Hock Soon

Context‐Based Coding of Adaptive Multiresolution Meshes

Tycowicz, Christoph von
Kälberer, Felix
Polthier, Konrad

Example‐Driven Deformations Based on Discrete Shells

Fröhlich, Stefan
Botsch, Mario

Making Imperfect Shadow Maps View‐Adaptive: High‐Quality Global Illumination in Large Dynamic Scenes

Ritschel, Tobias
Eisemann, Elmar
Ha, Inwoo
Kim, James D. K.
Seidel, Hans‐Peter

A Survey of Specularity Removal Methods

Artusi, Alessandro
Banterle, Francesco
Chetverikov, Dmitry

Pre‐computed Gathering of Multi‐Bounce Glossy Reflections

Laurijssen, Jurgen
Wang, Rui
Lagae, Ares
Dutré, Philip

Convolution‐Based Simulation of Homogeneous Subsurface Scattering

Munoz, Adolfo
Echevarria, Jose I.
Seron, Francisco J.
Gutierrez, Diego

Visualizing Strain Anisotropy in Mantle Flow Fields

Obermaier, H.
Billen, M. I.
Hagen, H.
Hering‐Bertram, M.
Hamann, B.

Social Network Clustering and Visualization using Hierarchical Edge Bundles

Jia, Yuntao
Garland, Michael
Hart, John C.

Perceptually Based Appearance Modification for Compliant Appearance Editing

Law, Alvin J.
Aliaga, Daniel G.
Sajadi, Behzad
Majumder, Aditi
Pizlo, Zygmunt

State‐of‐the‐Art Report on Temporal Coherence for Stylized Animations

Bénard, Pierre
Bousseau, Adrien
Thollot, Joëlle

Visualisation Techniques for Using Spatial Augmented Reality in the Design Process of a Car

Menk, Christoffer
Jundt, Eduard
Koch, Reinhard

A Flexible Approach for Output‐Sensitive Rendering of Animated Characters

Beacco, A.
Spanlang, B.
Andujar, C.
Pelechano, N.

An Optimal Control Approach for Texture Metamorphosis

Kabul, Ilknur
Pizer, Stephen M.
Rosenman, Julian
Niethammer, Marc

Hierarchical Deformation of Locally Rigid Meshes

Manson, Josiah
Schaefer, Scott

Computational Plenoptic Imaging

Wetzstein, Gordon
Ihrke, Ivo
Lanman, Douglas
Heidrich, Wolfgang

A General BRDF Representation Based on Tensor Decomposition

Bilgili, Ahmet
Öztürk, Aydn
Kurt, Murat

A New QEM for Parametrization of Raster Images

Yin, Xuetao
Femiani, John
Wonka, Peter
Razdan, Anshuman

Reviewers


32nd EUROGRAPHICS General Assembly


Computational Aesthetics 2011 in Vancouver, Canada, August 5–7, 2011, Sponsored by Eurographics, in Collaboration with ACM SIGGRAPH

Isenberg, Tobias
Cunningham, Douglas


BibTeX (30-Issue 8)
                
@article{
http::/diglib.eg.org/handle/10.1111/000_cgf_30_8_toc,
-,
journal = {Computer Graphics Forum}, title = {{
Table of Contents}},
author = {}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
http://diglib.eg.org/handle/10.1111/000_cgf_30_8_toc}
-}
}
                
@article{
10.1111:j.1467-8659.2011.01853.x,
journal = {Computer Graphics Forum}, title = {{
Simplex and Diamond Hierarchies: Models and Applications}},
author = {
Weiss, K.
 and
Floriani, L. De
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.01853.x}
}
                
@article{
10.1111:j.1467-8659.2011.01967.x,
journal = {Computer Graphics Forum}, title = {{
Learning Boundary Edges for 3D‐Mesh Segmentation}},
author = {
Benhabiles, Halim
 and
Lavoué, Guillaume
 and
Vandeborre, Jean‐Philippe
 and
Daoudi, Mohamed
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.01967.x}
}
                
@article{
10.1111:j.1467-8659.2011.01905.x,
journal = {Computer Graphics Forum}, title = {{
Non‐Linear Beam Tracing on a GPU}},
author = {
Liu, Baoquan
 and
Wei, Li‐Yi
 and
Yang, Xu
 and
Ma, Chongyang
 and
Xu, Ying‐Qing
 and
Guo, Baining
 and
Wu, Enhua
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.01905.x}
}
                
@article{
10.1111:j.1467-8659.2011.01968.x,
journal = {Computer Graphics Forum}, title = {{
Finding Syntactic Structures from Human Motion Data}},
author = {
Park, Jong Pil
 and
Lee, Kang Hoon
 and
Lee, Jehee
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.01968.x}
}
                
@article{
10.1111:j.1467-8659.2011.01969.x,
journal = {Computer Graphics Forum}, title = {{
Stroke Correspondence Construction Using Manifold Learning}},
author = {
Liu, Dongquan
 and
Chen, Quan
 and
Yu, Jun
 and
Gu, Huiqin
 and
Tao, Dacheng
 and
Seah, Hock Soon
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.01969.x}
}
                
@article{
10.1111:j.1467-8659.2011.01972.x,
journal = {Computer Graphics Forum}, title = {{
Context‐Based Coding of Adaptive Multiresolution Meshes}},
author = {
Tycowicz, Christoph von
 and
Kälberer, Felix
 and
Polthier, Konrad
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.01972.x}
}
                
@article{
10.1111:j.1467-8659.2011.01974.x,
journal = {Computer Graphics Forum}, title = {{
Example‐Driven Deformations Based on Discrete Shells}},
author = {
Fröhlich, Stefan
 and
Botsch, Mario
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.01974.x}
}
                
@article{
10.1111:j.1467-8659.2011.01998.x,
journal = {Computer Graphics Forum}, title = {{
Making Imperfect Shadow Maps View‐Adaptive: High‐Quality Global Illumination in Large Dynamic Scenes}},
author = {
Ritschel, Tobias
 and
Eisemann, Elmar
 and
Ha, Inwoo
 and
Kim, James D. K.
 and
Seidel, Hans‐Peter
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.01998.x}
}
                
@article{
10.1111:j.1467-8659.2011.01971.x,
journal = {Computer Graphics Forum}, title = {{
A Survey of Specularity Removal Methods}},
author = {
Artusi, Alessandro
 and
Banterle, Francesco
 and
Chetverikov, Dmitry
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.01971.x}
}
                
@article{
10.1111:j.1467-8659.2011.02001.x,
journal = {Computer Graphics Forum}, title = {{
Pre‐computed Gathering of Multi‐Bounce Glossy Reflections}},
author = {
Laurijssen, Jurgen
 and
Wang, Rui
 and
Lagae, Ares
 and
Dutré, Philip
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02001.x}
}
                
@article{
10.1111:j.1467-8659.2011.02034.x,
journal = {Computer Graphics Forum}, title = {{
Convolution‐Based Simulation of Homogeneous Subsurface Scattering}},
author = {
Munoz, Adolfo
 and
Echevarria, Jose I.
 and
Seron, Francisco J.
 and
Gutierrez, Diego
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02034.x}
}
                
@article{
10.1111:j.1467-8659.2011.02036.x,
journal = {Computer Graphics Forum}, title = {{
Visualizing Strain Anisotropy in Mantle Flow Fields}},
author = {
Obermaier, H.
 and
Billen, M. I.
 and
Hagen, H.
 and
Hering‐Bertram, M.
 and
Hamann, B.
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02036.x}
}
                
@article{
10.1111:j.1467-8659.2011.02037.x,
journal = {Computer Graphics Forum}, title = {{
Social Network Clustering and Visualization using Hierarchical Edge Bundles}},
author = {
Jia, Yuntao
 and
Garland, Michael
 and
Hart, John C.
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02037.x}
}
                
@article{
10.1111:j.1467-8659.2011.02035.x,
journal = {Computer Graphics Forum}, title = {{
Perceptually Based Appearance Modification for Compliant Appearance Editing}},
author = {
Law, Alvin J.
 and
Aliaga, Daniel G.
 and
Sajadi, Behzad
 and
Majumder, Aditi
 and
Pizlo, Zygmunt
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02035.x}
}
                
@article{
10.1111:j.1467-8659.2011.02075.x,
journal = {Computer Graphics Forum}, title = {{
State‐of‐the‐Art Report on Temporal Coherence for Stylized Animations}},
author = {
Bénard, Pierre
 and
Bousseau, Adrien
 and
Thollot, Joëlle
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02075.x}
}
                
@article{
10.1111:j.1467-8659.2011.02066.x,
journal = {Computer Graphics Forum}, title = {{
Visualisation Techniques for Using Spatial Augmented Reality in the Design Process of a Car}},
author = {
Menk, Christoffer
 and
Jundt, Eduard
 and
Koch, Reinhard
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02066.x}
}
                
@article{
10.1111:j.1467-8659.2011.02065.x,
journal = {Computer Graphics Forum}, title = {{
A Flexible Approach for Output‐Sensitive Rendering of Animated Characters}},
author = {
Beacco, A.
 and
Spanlang, B.
 and
Andujar, C.
 and
Pelechano, N.
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02065.x}
}
                
@article{
10.1111:j.1467-8659.2011.02067.x,
journal = {Computer Graphics Forum}, title = {{
An Optimal Control Approach for Texture Metamorphosis}},
author = {
Kabul, Ilknur
 and
Pizer, Stephen M.
 and
Rosenman, Julian
 and
Niethammer, Marc
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02067.x}
}
                
@article{
10.1111:j.1467-8659.2011.02074.x,
journal = {Computer Graphics Forum}, title = {{
Hierarchical Deformation of Locally Rigid Meshes}},
author = {
Manson, Josiah
 and
Schaefer, Scott
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02074.x}
}
                
@article{
10.1111:j.1467-8659.2011.02073.x,
journal = {Computer Graphics Forum}, title = {{
Computational Plenoptic Imaging}},
author = {
Wetzstein, Gordon
 and
Ihrke, Ivo
 and
Lanman, Douglas
 and
Heidrich, Wolfgang
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111:j.1467-8659.2011.02073.x}
}
                
@article{
10.1111:j.1467-8659.2011.02072.x,
journal = {Computer Graphics Forum}, title = {{
A General BRDF Representation Based on Tensor Decomposition}},
author = {
Bilgili, Ahmet
 and
Öztürk, Aydn
 and
Kurt, Murat
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02072.x}
}
                
@article{
10.1111:j.1467-8659.2011.02071.x,
journal = {Computer Graphics Forum}, title = {{
A New QEM for Parametrization of Raster Images}},
author = {
Yin, Xuetao
 and
Femiani, John
 and
Wonka, Peter
 and
Razdan, Anshuman
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02071.x}
}
                
@article{
10.1111:j.1467-8659.2011.02080.x,
journal = {Computer Graphics Forum}, title = {{
Reviewers}},
author = {}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02080.x}
}
                
@article{
10.1111:j.1467-8659.2011.02068.x,
journal = {Computer Graphics Forum}, title = {{
32nd EUROGRAPHICS General Assembly}},
author = {}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02068.x}
}
                
@article{
10.1111:j.1467-8659.2011.02076.x,
journal = {Computer Graphics Forum}, title = {{
Computational Aesthetics 2011 in Vancouver, Canada, August 5–7, 2011, Sponsored by Eurographics, in Collaboration with ACM SIGGRAPH}},
author = {
Isenberg, Tobias
 and
Cunningham, Douglas
}, year = {
2011},
publisher = {
The Eurographics Association and Blackwell Publishing Ltd.},
ISSN = {1467-8659},
DOI = {
10.1111/j.1467-8659.2011.02076.x}
}

Browse

Recent Submissions

Now showing 1 - 26 of 26
  • Item
    Table of Contents
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Eduard Groeller and Holly Rushmeier
  • Item
    Simplex and Diamond Hierarchies: Models and Applications
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Weiss, K.; Floriani, L. De; Eduard Groeller and Holly Rushmeier
    Hierarchical spatial decompositions are a basic modelling tool in a variety of application domains. Several papers on this subject deal with hierarchical simplicial decompositions generated through regular simplex bisection. Such decompositions, originally developed for finite elements, are extensively used as the basis for multi‐resolution models of scalar fields, such as terrains, and static or time‐varying volume data. They have also been used as an alternative to quadtrees and octrees as spatial access structures. The primary distinction among all such approaches is whether they treat the simplex or clusters of simplices, called diamonds, as the modelling primitive. This leads to two classes of data structures and to different query approaches. We present the hierarchical models in a dimension‐independent manner, and organize the description of the various applications, primarily interactive terrain rendering and isosurface extraction, according to the dimension of the domain.
  • Item
    Learning Boundary Edges for 3D‐Mesh Segmentation
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Benhabiles, Halim; Lavoué, Guillaume; Vandeborre, Jean‐Philippe; Daoudi, Mohamed; Eduard Groeller and Holly Rushmeier
    This paper presents a 3D‐mesh segmentation algorithm based on a learning approach. A large database of manually segmented 3D‐meshes is used to learn a boundary edge function. The function is learned using a classifier which automatically selects from a pool of geometric features the most relevant ones to detect candidate boundary edges. We propose a processing pipeline that produces smooth closed boundaries using this edge function. This pipeline successively selects a set of candidate boundary contours, closes them and optimizes them using a snake movement. Our algorithm was evaluated quantitatively using two different segmentation benchmarks and was shown to outperform most recent algorithms from the state‐of‐the‐art.
  • Item
    Non‐Linear Beam Tracing on a GPU
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Liu, Baoquan; Wei, Li‐Yi; Yang, Xu; Ma, Chongyang; Xu, Ying‐Qing; Guo, Baining; Wu, Enhua; Eduard Groeller and Holly Rushmeier
    Beam tracing combines the flexibility of ray tracing and the speed of polygon rasterization. However, beam tracing so far only handles linear transformations; thus, it is only applicable to linear effects such as planar mirror reflections but not to non‐linear effects such as curved mirror reflection, refraction, caustics and shadows. In this paper, we introduce non‐linear beam tracing to render these non‐linear effects. Non‐linear beam tracing is highly challenging because commodity graphics hardware supports only linear vertex transformation and triangle rasterization. We overcome this difficulty by designing a non‐linear graphics pipeline and implementing it on top of a commodity GPU. This allows beams to be non‐linear where rays within the same beam do not have to be parallel or intersect at a single point. Using these non‐linear beams, real‐time GPU applications can render secondary rays via polygon streaming similar to how they render primary rays. A major strength of this methodology is that it naturally supports fully dynamic scenes without the need to pre‐store a scene database. Utilizing our approach, non‐linear ray tracing effects can be rendered in real‐time on a commodity GPU under a unified framework.
  • Item
    Finding Syntactic Structures from Human Motion Data
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Park, Jong Pil; Lee, Kang Hoon; Lee, Jehee; Eduard Groeller and Holly Rushmeier
    We present a new approach to motion rearrangement that preserves the syntactic structures of an input motion automatically by learning a context‐free grammar from the motion data. For grammatical analysis, we reduce an input motion into a string of terminal symbols by segmenting the motion into a series of subsequences, and then associating a group of similar subsequences with the same symbol. To obtain the most repetitive and precise set of terminals, we search for an optimial segmentation such that a large number of subsequences can be clustered into groups with little error. Once the input motion has been encoded as a string, a grammar induction algorithm is employed to build up a context‐free grammar so that the grammar can reconstruct the original string accurately as well as generate novel strings sharing their syntactic structures with the original string. Given any new strings from the learned grammar, it is straightforward to synthesize motion sequences by replacing each terminal symbol with its associated motion segment, and stitching every motion segment sequentially. We demonstrate the usefulness and flexibility of our approach by learning grammars from a large diversity of human motions, and reproducing their syntactic structures in new motion sequences.
  • Item
    Stroke Correspondence Construction Using Manifold Learning
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Liu, Dongquan; Chen, Quan; Yu, Jun; Gu, Huiqin; Tao, Dacheng; Seah, Hock Soon; Eduard Groeller and Holly Rushmeier
    Stroke correspondence construction is a precondition for generating inbetween frames from a set of key frames. In our case, each stroke in a key frame is a vector represented as a Disk B‐Spline Curve (DBSC) which is a flexible and compact vector format. However, it is not easy to construct correspondences between multiple DBSC strokes effectively because of the following points: (1) with the use of shape descriptors, the dimensionality of the feature space is high; (2) the number of strokes in different key frames is usually large and different from each other and (3) the length of corresponding strokes can be very different. The first point makes matching difficult. The other two points imply ‘many to many’ and ‘part to whole’ correspondences between strokes. To solve these problems, this paper presents a DBSC stroke correspondence construction approach, which introduces a manifold learning technique to the matching process. Moreover, in order to handle the mapping between unequal numbers of strokes with different lengths, a stroke reconstruction algorithm is developed to convert the ‘many to many’ and ‘part to whole’ stroke correspondences to ‘one to one’ compound stroke correspondence.
  • Item
    Context‐Based Coding of Adaptive Multiresolution Meshes
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Tycowicz, Christoph von; Kälberer, Felix; Polthier, Konrad; Eduard Groeller and Holly Rushmeier
    Multiresolution meshes provide an efficient and structured representation of geometric objects. To increase the mesh resolution only at vital parts of the object, adaptive refinement is widely used. We propose a lossless compression scheme for these adaptive structures that exploits the parent–child relationships inherent to the mesh hierarchy. We use the rules that correspond to the adaptive refinement scheme and store bits only where some freedom of choice is left, leading to compact codes that are free of redundancy. Moreover, we extend the coder to sequences of meshes with varying refinement. The connectivity compression ratio of our method exceeds that of state‐of‐the‐art coders by a factor of 2–7. For efficient compression of vertex positions we adapt popular wavelet‐based coding schemes to the adaptive triangular and quadrangular cases to demonstrate the compatibility with our method. Akin to state‐of‐the‐art coders, we use a zerotree to encode the resulting coefficients. Using improved context modelling we enhanced the zerotree compression, cutting the overall geometry data rate by 7% below those of the successful Progressive Geometry Compression. More importantly, by exploiting the existing refinement structure we achieve compression factors that are four times greater than those of coders which can handle irregular meshes.
  • Item
    Example‐Driven Deformations Based on Discrete Shells
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Fröhlich, Stefan; Botsch, Mario; Eduard Groeller and Holly Rushmeier
    Despite the huge progress made in interactive physics‐based mesh deformation, manipulating a geometrically complex mesh or posing a detailed character is still a tedious and time‐consuming task. Example‐driven methods significantly simplify the modelling process by incorporating structural or anatomical knowledge learned from example poses. However, these approaches yield counter‐intuitive, non‐physical results as soon as the shape space spanned by the example poses is left. In this paper, we propose a modelling framework that is both example‐driven and physics‐based and thereby overcomes the limitations of both approaches. Based on an extension of the discrete shell energy we derive mesh deformation and mesh interpolation techniques that can be seamlessly combined into a simple and flexible mesh‐based inverse kinematics system.
  • Item
    Making Imperfect Shadow Maps View‐Adaptive: High‐Quality Global Illumination in Large Dynamic Scenes
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Ritschel, Tobias; Eisemann, Elmar; Ha, Inwoo; Kim, James D. K.; Seidel, Hans‐Peter; Eduard Groeller and Holly Rushmeier
    We propose an algorithm to compute interactive indirect illumination in dynamic scenes containing millions of triangles. It makes use of virtual point lights (VPL) to compute bounced illumination and a point‐based scene representation to query indirect visibility, similar to Imperfect Shadow Maps (ISM). To ensure a high fidelity of indirect light and shadows, our solution is made view‐adaptive by means of two orthogonal improvements: First, the VPL distribution is chosen to provide more detail, that is, more dense VPL sampling, where these contribute most to the current view. Second, the scene representation for indirect visibility is adapted to ensure geometric detail where it affects indirect shadows in the current view.
  • Item
    A Survey of Specularity Removal Methods
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Artusi, Alessandro; Banterle, Francesco; Chetverikov, Dmitry; Eduard Groeller and Holly Rushmeier
    The separation of reflection components is an important issue in computer graphics, computer vision and image processing. It provides useful information for the applications that need consistent object surface appearance, such as stereo reconstruction, visual recognition, tracking, objects re‐illumination and dichromatic editing. In this paper we will present a brief survey of recent advances in separation of reflection components, also known as specularity (highlights) removal. Several techniques that try to tackle the problem from different points of view have been proposed so far. In this survey, we will overview these methods and we will present a critical analysis of their benefits and drawbacks.
  • Item
    Pre‐computed Gathering of Multi‐Bounce Glossy Reflections
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Laurijssen, Jurgen; Wang, Rui; Lagae, Ares; Dutré, Philip; Eduard Groeller and Holly Rushmeier
    Recent work in interactive global illumination addresses diffuse and moderately glossy indirect lighting effects, but high‐frequency effects such as multi‐bounce reflections on highly glossy surfaces are often ignored. Accurately simulating such effects is important to convey the realistic appearance of materials such as chrome and shiny metal. In this paper, we present an efficient method for visualizing multi‐bounce glossy reflections at interactive rates under environment lighting. Our main contribution is a pre‐computation–based method which efficiently gathers subsequent highly glossy reflection passes modelled with a non‐linear transfer function representation based on the von Mises–Fisher distribution. We show that our gathering method is superior to scattered sampling. To exploit the sparsity of the pre‐computed data, we apply perfect spatial hashing. As a result, we are able to visualize multi‐bounce glossy reflections at interactive rates at a low pre‐computation cost.
  • Item
    Convolution‐Based Simulation of Homogeneous Subsurface Scattering
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Munoz, Adolfo; Echevarria, Jose I.; Seron, Francisco J.; Gutierrez, Diego; Eduard Groeller and Holly Rushmeier
    This paper introduces a new method for simulating homogeneous subsurface light transport in translucent objects. Our approach is based on irradiance convolutions over a multi‐layered representation of the volume for light transport, which is general enough to obtain plausible depictions of translucent objects based on the diffusion approximation. We aim at providing an efficient physically based algorithm that can apply arbitrary diffusion profiles to general geometries. We obtain accurate results for a wide range of materials, on par with the hierarchical method by Jensen and Buhler.
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    Visualizing Strain Anisotropy in Mantle Flow Fields
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Obermaier, H.; Billen, M. I.; Hagen, H.; Hering‐Bertram, M.; Hamann, B.; Eduard Groeller and Holly Rushmeier
    The evolution of strain and development of material anisotropy in models of the Earth’s mantle flow convey important information about how to interpret the geometric relationship between observation of seismic anisotropy and the actual mantle flow field. By combining feature extraction techniques such as path line integration and tensor accumulation, we compute time‐varying strain vector fields that build the foundation for a number of feature extraction and visualization techniques. The proposed field segmentation, clustering, histograms and multi‐volume visualization techniques facilitate an intuitive understanding of three‐dimensional strain in such flow fields, overcoming limitations of previous methods such as 2‐D line plots and slicing. We present applications of our approach to an artificial time varying flow data set and a real world example of stationary flow in a subduction zone and discuss the challenges of processing these geophysical data sets as well as the insights gained.
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    Social Network Clustering and Visualization using Hierarchical Edge Bundles
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Jia, Yuntao; Garland, Michael; Hart, John C.; Eduard Groeller and Holly Rushmeier
    The hierarchical edge bundle (HEB) method generates useful visualizations of dense graphs, such as social networks, but requires a predefined clustering hierarchy, and does not easily benefit from existing straight‐line visualization improvements. This paper proposes a new clustering approach that extracts the community structure of a network and organizes it into a hierarchy that is flatter than existing community‐based clustering approaches and maps better to HEB visualization. Our method not only discovers communities and generates clusters with better modularization qualities, but also creates a balanced hierarchy that allows HEB visualization of unstructured social networks without predefined hierarchies. Results on several data sets demonstrate that this approach clarifies real‐world communication, collaboration and competition network structure and reveals information missed in previous visualizations. We further implemented our techniques into a social network visualization application on facebook.com and let users explore the visualization and community clustering of their own social networks.
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    Perceptually Based Appearance Modification for Compliant Appearance Editing
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Law, Alvin J.; Aliaga, Daniel G.; Sajadi, Behzad; Majumder, Aditi; Pizlo, Zygmunt; Eduard Groeller and Holly Rushmeier
    Projection‐based appearances are used in a variety of computer graphics applications to impart different appearances onto physical surfaces using digitally controlled projector light. To achieve a compliant appearance, all points on the physical surface must be altered to the colours of the desired target appearance; otherwise, an incompliant appearance results in a misleading visualization. Previous systems typically assume to operate with compliant appearances or restrict themselves to the simpler case of white surfaces. To achieve compliancy, one may change the physical surface's albedo, increase the amount of projector light radiance available or modify the target appearance's colours. This paper presents an approach to modify a target appearance to achieve compliant appearance editing without altering the physical surface or the projector setup. Our system minimally alters the target appearance's colours while maintaining cues important for perceptual similarity (e.g. colour constancy). First, we discuss how to measure colour compliancy. Next, we describe our approach to partition the physical surface into patches based on the surface's colours and the target appearance's colours. Finally, we describe our appearance optimization process, which computes a compliant appearance that is as perceptually similar as possible to the target appearance's colours. We perform several real‐world projection‐based appearances and compare our results to naïve approaches, which either ignore compliancy or simply reduce the appearance's overall brightness.
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    State‐of‐the‐Art Report on Temporal Coherence for Stylized Animations
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Bénard, Pierre; Bousseau, Adrien; Thollot, Joëlle; Eduard Groeller and Holly Rushmeier
    Non‐photorealistic rendering (NPR) algorithms allow the creation of images in a variety of styles, ranging from line drawing and pen‐and‐ink to oil painting and watercolour. These algorithms provide greater flexibility, control and automation over traditional drawing and painting. Despite significant progress over the past 15 years, the application of NPR to the generation of stylized animations remains an active area of research. The main challenge of computer‐generated stylized animations is to reproduce the look of traditional drawings and paintings while minimizing distracting flickering and sliding artefacts present in hand‐drawn animations. These goals are inherently conflicting and any attempt to address the temporal coherence of stylized animations is a trade‐off. This state‐of‐the‐art report is motivated by the growing number of methods proposed in recent years and the need for a comprehensive analysis of the trade‐offs they propose. We formalize the problem of temporal coherence in terms of goals and compare existing methods accordingly. We propose an analysis for both line and region stylization methods and discuss initial steps towards their perceptual evaluation. The goal of our report is to help uninformed readers to choose the method that best suits their needs, as well as motivate further research to address the limitations of existing methods.
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    Visualisation Techniques for Using Spatial Augmented Reality in the Design Process of a Car
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Menk, Christoffer; Jundt, Eduard; Koch, Reinhard; Eduard Groeller and Holly Rushmeier
    If spatial augmented reality is used in the design process of a car, then one of the most important issues is that the virtual content is projected with a very high visual quality onto the real object, because based on this projection design decisions are made. Especially, the visualised colours on the real object should not be distinguishable from corresponding real reference colours. In this paper, we introduce a new approach for the augmentation of real objects which is able to match the requirements of a design process. We present a new rendering method with ray tracing which increases the visual quality of the projection images in comparison to existing methods. The desired values of these images have further to be adjusted according to the material, the ambient light and the local orientation of the projector. For this purpose, we develop a physically based computation which exactly determines the corresponding projection intensities for these values by using three‐dimensional lookup tables at every projector pixel. Since not all of the desired values can be represented with an intensity of the projector, an adjustment has to be computed for these values. Therefore, we conduct a user study with design experts who work in the automotive industry and use the results to propose a new adjustment method for such values. Finally, we compare our methods to existing procedures and conclude which ones are suitable for the design process of a car.
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    A Flexible Approach for Output‐Sensitive Rendering of Animated Characters
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Beacco, A.; Spanlang, B.; Andujar, C.; Pelechano, N.; Eduard Groeller and Holly Rushmeier
    Rendering detailed animated characters is a major limiting factor in crowd simulation. In this paper we present a new representation for 3D animated characters which supports output‐sensitive rendering. Our approach is flexible in the sense that it does not require us to pre‐define the animation sequences beforehand, nor to pre‐compute a dense set of pre‐rendered views for each animation frame. Each character is encoded through a small collection of textured boxes storing colour and depth values. At runtime, each box is animated according to the rigid transformation of its associated bone and a fragment shader is used to recover the original geometry using a dual‐depth version of relief mapping. Unlike competing output‐sensitive approaches, our compact representation is able to recover high‐frequency surface details and reproduces view‐motion parallax effectively. Our approach drastically reduces both the number of primitives being drawn and the number of bones influencing each primitive, at the expense of a very slight per‐fragment overhead. We show that, beyond a certain distance threshold, our compact representation is much faster to render than traditional level‐of‐detail triangle meshes. Our user study demonstrates that replacing polygonal geometry by our impostors produces negligible visual artefacts.
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    An Optimal Control Approach for Texture Metamorphosis
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Kabul, Ilknur; Pizer, Stephen M.; Rosenman, Julian; Niethammer, Marc; Eduard Groeller and Holly Rushmeier
    In this paper, we introduce a new texture metamorphosis approach for interpolating texture samples from a source texture into a target texture. We use a new energy optimization scheme derived from optimal control principles which exploits the structure of the metamorphosis optimality conditions. Our approach considers the change in pixel position and pixel appearance in a single framework. In contrast to previous techniques that compute a global warping based on feature masks of textures, our approach allows to transform one texture into another by considering both intensity values and structural features of textures simultaneously. We demonstrate the usefulness of our approach for different textures, such as stochastic, semi‐structural and regular textures, with different levels of complexities. Our method produces visually appealing transformation sequences with no user interaction.
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    Hierarchical Deformation of Locally Rigid Meshes
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Manson, Josiah; Schaefer, Scott; Eduard Groeller and Holly Rushmeier
    We propose a method for calculating deformations of models by deforming a low‐resolution mesh and adding details while ensuring that the details we add satisfy a set of constraints. Our method builds a low‐resolution representation of a mesh by using edge collapses and performs an as‐rigid‐as‐possible deformation on the simplified mesh. We then add back details by reversing edge‐collapses so that the shape of the mesh is locally preserved. While adding details, we deform the mesh to match the predicted positions of constraints so that constraints on the full‐resolution mesh are met. Our method operates on meshes with arbitrary triangulations, satisfies constraints over the full‐resolution mesh and converges quickly.
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    Computational Plenoptic Imaging
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Wetzstein, Gordon; Ihrke, Ivo; Lanman, Douglas; Heidrich, Wolfgang; Eduard Groeller and Holly Rushmeier
    The plenoptic function is a ray‐based model for light that includes the colour spectrum as well as spatial, temporal and directional variation. Although digital light sensors have greatly evolved in the last years, one fundamental limitation remains: all standard CCD and CMOS sensors integrate over the dimensions of the plenoptic function as they convert photons into electrons; in the process, all visual information is irreversibly lost, except for a two‐dimensional, spatially varying subset—the common photograph. In this state‐of‐the‐art report, we review approaches that optically encode the dimensions of the plenoptic function transcending those captured by traditional photography and reconstruct the recorded information computationally.
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    A General BRDF Representation Based on Tensor Decomposition
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Bilgili, Ahmet; Öztürk, Aydn; Kurt, Murat; Eduard Groeller and Holly Rushmeier
    Generating photo‐realistic images through Monte Carlo rendering requires efficient representation of light–surface interaction and techniques for importance sampling. Various models with good representation abilities have been developed but only a few of them have their importance sampling procedure. In this paper, we propose a method which provides a good bidirectional reflectance distribution function (BRDF) representation and efficient importance sampling procedure. Our method is based on representing BRDF as a function of tensor products. Four‐dimensional measured BRDF tensor data are factorized using Tucker decomposition. A large data set is used for comparing the proposed BRDF model with a number of well‐known BRDF models. It is shown that the underlying model provides good approximation to BRDFs.
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    A New QEM for Parametrization of Raster Images
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Yin, Xuetao; Femiani, John; Wonka, Peter; Razdan, Anshuman; Eduard Groeller and Holly Rushmeier
    We present an image processing method that converts a raster image to a simplical two‐complex which has only a small number of vertices (base mesh) plus a parametrization that maps each pixel in the original image to a combination of the barycentric coordinates of the triangle it is finally mapped into. Such a conversion of a raster image into a base mesh plus parametrization can be useful for many applications such as segmentation, image retargeting, multi‐resolution editing with arbitrary topologies, edge preserving smoothing, compression, etc. The goal of the algorithm is to produce a base mesh such that it has a small colour distortion as well as high shape fairness, and a parametrization that is globally continuous visually and numerically. Inspired by multi‐resolution adaptive parametrization of surfaces and quadric error metric, the algorithm converts pixels in the image to a dense triangle mesh and performs error‐bounded simplification jointly considering geometry and colour. The eliminated vertices are projected to an existing face. The implementation is iterative and stops when it reaches a prescribed error threshold. The algorithm is feature‐sensitive, i.e. salient feature edges in the images are preserved where possible and it takes colour into account thereby producing a better quality triangulation.
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    Reviewers
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Eduard Groeller and Holly Rushmeier
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    32nd EUROGRAPHICS General Assembly
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Eduard Groeller and Holly Rushmeier
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    Computational Aesthetics 2011 in Vancouver, Canada, August 5–7, 2011, Sponsored by Eurographics, in Collaboration with ACM SIGGRAPH
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Isenberg, Tobias; Cunningham, Douglas; Eduard Groeller and Holly Rushmeier