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GRAPP 2008 Abstracts |
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Conference
Area 1 - Geometry and Modeling
Area 2 - Rendering
Area 3 - Animation and Simulation
Area 4 - Interactive Environments
Special Sessions
Art, Science and Technology, Virtual tools for Cultural Heritage
Multimedia Collaborative Virtual Environments
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Area 1 - Geometry and Modeling |
Paper Nr.: |
59 |
Title: |
GEOMETRIC ALGORITHMS ON CUDA |
Author(s): |
Antonio J. Rueda and Lidia Ortega |
Abstract: |
The recent launch of the NVIDIA CUDA technology has opened a new era
in the young field of GPGPU (General Purpose computation on GPUs).
This technology allows the design and implementation of parallel algorithms
in a much simpler way than previous approaches based on shader programming.
The present work explores the possibilities of CUDA for solving basic
geometric problems on 3D meshes like the point inclusion test or the
self-intersection detection. A solution to these problems can be implemented
in CUDA with only a small fraction of the effort required to design
and implement an equivalent solution using shader programming, and
the results are impressive when compared to a CPU execution. |
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Paper Nr.: |
60 |
Title: |
VORONOI DIAGRAM AND ITS APPLICATION TO SPATIAL CALIBRATION FOR GAMMA CAMERA IMAGES |
Author(s): |
Brian D. Maisler, Hong Liu, J. E. McKisson, Yishi Li and Eric Kvam |
Abstract: |
Gamma
camera images obtained from PSPMT detectors and segmented crystal
scintillators to be used for scintimammography are often distorted and
blurred. Our software application is used to restore flood-field gamma
camera images and map the peak positions of individual charge clusters
back to the positions of the corresponding source scintillations. Since
the exact position of scintillation in a crystal grain is not
controllable due to the randomness of scattering, a region-to-region
location map is more statistically sound than a point-to-point position
map. Traditionally, an array of rectangles centered at the restored
peaks of charge clusters is mapped to an array of crystal grains from
which the source scintillations are emitted. We observe that the
mapping is essentially a nearest neighborhood problem and innovatively
introduce the Voronoi diagram to replace the rectangular array. The
natural fit of the Voronoi diagram to the essence of neighborhood
problem significantly improves the likelihood of correct mapping. It
also makes our mapping method adaptable to apply to crystal plates in
other geometric configurations. We implement the computations of
Voronoi diagrams via OpenGL. As an empirical software solution, the
images restored from raw flood field images illustrate high level
uniformity and linearity. |
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Paper Nr.: |
63 |
Title: |
CORNER DETECTION ON CURVES |
Author(s): |
Neeta Nain, Vijay Laxmi and Bhavitavya Bhadviya |
Abstract: |
Detection
of discontinuity plays an important role in image registration, image
comparison, image segmentation, time sequence analysis and object
recognition. This paper presents a new approach for Corner Detection
using First Order Difference Chain-Encoding. Since the proposed method
is based on integer operations it is very simple and efficient.
Preliminary results are presented and evaluation with respect to
standard corner detectors is done as a benchmark. |
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Paper Nr.: |
71 |
Title: |
QUALITY PERCEPTION OF SIMPLIFIED MODELS: NSA VS QSLIM |
Author(s): |
Frutuoso G. M. Silva and Samuel S. Silva |
Abstract: |
Quality
perception of simplified models is an important aspect for several
applications. But, it is normally evaluated only based on the analysis
of geometrical errors of the simplified models. However, the analysis
of geometrical errors is not enough to evaluate the quality of the
simplified models. The quality of the simplified models and the
execution times are the main aspects that distinguish the
simplification algorithms. These algorithms have a great interest in a
variety of areas, since they allow the replacement of large models by
approximations with far fewer cells for manipulation and visualization
purposes. This paper presents a comparison between two simplification
algorithms, NSA and Qslim, and shows the difference between geometrical
and graphical quality. The comparison of results was made using the
PolyMeCo tool. It is a tool which enhances how users perform mesh
analysis and comparison, by providing an environment where several
visualization options and metrics are available and can be used in a
coordinated way. |
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Paper Nr.: |
82 |
Title: |
ANALYSIS OF POINT CLOUDS - Using Conformal Geometric Algebra |
Author(s): |
Dietmar Hildenbrand and Eckhard Hitzer |
Abstract: |
This paper presents some basics for the
analysis of point clouds using the geometrically intuitive
mathematical framework of conformal geometric algebra. In this
framework it is easy to compute with osculating circles for the
description of local curvature. Also methods for the fitting of
spheres as well as bounding spheres are presented. In a nutshell,
this paper provides a starting point for shape analysis based on
this new, geometrically intuitive and promising technology. |
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Paper Nr.: |
85 |
Title: |
DETECTION OF FACES IN WIRE-FRAME POLYHEDRA - Interactive Modelling of Uniform Polyhedra |
Author(s): |
Hidetoshi Nonaka |
Abstract: |
This
paper presents an interactive modelling system of uniform polyhedra
including regular polyhedra, semi-regular polyhedra, and intersected
concave polyhedra. In our system, user can virtually "make" and
"handle" them interactively. The coordinate of vertices are computed
without the knowledge of faces, solids, or metric information, but only
with the isomorphic graph structure. After forming a wire-frame
polyhedron, the faces are detected semi-automatically through
user-computer interaction. This sytem can be applied to recreational
mathematics, computer assisted education of the graph theory, and so on. |
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Paper Nr.: |
86 |
Title: |
MESH SIMPLIFICATION USING DISTANCE LABELS FOR VIEW-INDEPENDENT SILHOUETTE PRESERVATION |
Author(s): |
Susana Mata, Luis Pastor and Angel Rodríguez |
Abstract: |
Multiresolution
modelling presents itself as a good approach in order to reach a
compromise between quality and performance in the rendering of complex
scenes.
Within this framework, the detection and preservation of outstanding
features, such us silhouettes, become of great importance.
The goal of this paper is to present a technique based on Distance
Transforms
that allows to classify the mesh's elements according to their
proximity to
\nuevo{both the internal and }the external contour and makes use of
this information for weighting the
approximation error
which will be tolerated during the mesh simplification
process.
The approach followed in this work precomputes silhouettes for a given
set of cameras and performs an estimation for any other point of view.
The obtained results are evaluated in two ways: visually and using an
objective
metric that
measures the geometrical difference between two polygonal meshes. |
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Paper Nr.: |
96 |
Title: |
THE GROUNDED HEIGHTMAP TREE - A New Data Structure for Terrain Representation |
Author(s): |
J. Alonso and R. Joan-Arinyo |
Abstract: |
Terrain modeling is a fast growing field with many applications such as
computer graphics, resource management, Earth and environmental sciences,
civil and military engineering, surveying and photogrammetry and
games programming.
One of the most widely used terrain model is the Digital Elevation
Model (DEM). A DEM is a simple regularly spaced grid of elevation
points that represent the continuous variation of relief over space.
DEMs require simple storage and are compatible with
satellite data. However, they do not easily account for overhangs.
In this work we report on the Grounded Heightmap Tree, a new data
structure for terrain representation built as a generalization of the
DEM. The new data structure allows to naturally represent terrain
overhangs.
We illustrate the performance of the Grounded Heightmap Tree when
applied to represent terrains that undergo big changes.
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Paper Nr.: |
98 |
Title: |
EXPERIMENTAL STUDY OF BOUNDING BOX ALGORITHMS |
Author(s): |
Darko Dimitrov, Mathias Holst, Christian Knauer and Klaus Kriegel |
Abstract: |
The
computation of the minimum-volume bounding box of a point set in R^3 is
a hard problem. The best known exact algorithm requires O(n^3) time, so
several approximation algorithms and heuristics are preferred in
practice. Among them, the algorithm based on PCA (Principal Component
Analysis) plays an important role. Recently, it has been shown that the
discrete PCA algorithm may fail to approximate the minimum-volume
bounding box even for a large constant factor. Moreover, this happens
only for some very special examples with point clusters. As an
alternative, it has been proven that the continuous version of PCA
overcomes these problems.
The contribution of this paper is two-fold. First, we study the impact
of the recent theoretical results on applications of several PCA
variants in practice. We analyze the advantages and disadvantages of
the different variants on realistic inputs, randomly generated inputs,
and specially constructed (worst case) instances. Second, we evaluate
and compare the performances of several existing bounding box
algorithms. |
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Paper Nr.: |
101 |
Title: |
IMAGE-BASED 3D TORSO BODY MODELING |
Author(s): |
YoungJun Kim, Kunwoo Lee and Wontae Kim |
Abstract: |
This
paper proposes an image-based 3D modeling algorithm for a 3D torso of
the human body. This approach provides an easy and practical way of
modeling so that doctors can obtain the subject’s 3D data without
additional equipment such as a 3D scanner or MRI. To achieve this goal,
a 3D template model with feature points is prepared, and then a 3D
model of the subject is reconstructed from orthogonal photographs by
deforming the 3D template model. An appropriate number of feature
points and their positions are derived. Procrustes Analysis and Radial
Basis Functions (RBFs) are applied for the deformation. After the
deformations, images are mapped onto the mesh for visualization. |
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Paper Nr.: |
102 |
Title: |
SURFACE-SURFACE INTERSECTION BY HERMITE INTERPOLATION |
Author(s): |
Eng-Wee Chionh |
Abstract: |
A
fast heuristic to approximate the intersection curve of two surface
patches was originally proposed by Sederberg and Nishita. The patches
are rationally parametrized and they cut each other transversely. This
paper reports a simple generalization that greatly improves the
accuracy of the original heuristic. The generalization eihter avoids or
attenuates the approximation error. Avoidance is achieved when the
improved heuristic produces the exact intersection curve; attenuation
is accomplished with an aggregate square distance formula guiding the
selection of a generalized constraint for a better fit. |
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Paper Nr.: |
105 |
Title: |
A HIERARCHICAL SPATIAL INDEX FOR TRIANGULATED SURFACES |
Author(s): |
Leila De Floriani, Marianna Facinoli, Paola Magillo and Debora Dimitri |
Abstract: |
We present the PM2-Triangle quadtree (PM2T-quadtree),
a new hierarchical spatial index for triangle meshes
which has been designed
for performing spatial queries on triangle-based terrain models.
The PM2T-quadtree is based on a recursive space decomposition into
square blocks.
Here, we propose a highly compact data structure encoding a PM2T-quadtree,
which decouples the spatial indexing structure from the combinatorial
description of the mesh.
We compare the PM2T-quadtree against other spatial indexes
by considering the structure of the underlying domain subdivision,
the storage costs
of their data structures and the performance in geometric queries. |
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Paper Nr.: |
108 |
Title: |
EFFICIENT FACE-BASED NON-SPLIT CONNECTIVITY COMPRESSION FOR QUAD AND TRIANGLE-QUAD MESHES |
Author(s): |
D. R. Khattab, Y. M. Abd El-Latif, M. S. Abdel Wahab and M. F. Tolba |
Abstract: |
In
this paper we present an efficient face based connectivity coding
technique for the special class of quadrilateral and the hybrid
triangular-quadrilateral meshes. This work extends the main ideas of
non-split encoding presented by the first contribution of the authors
(Khattab, Abd El-Latif, Abdel Wahab and Tolba, 2007) for triangle
meshes and improves over the compression results provided so far for
existing face based connectivity compression techniques. It achieves an
average compression ratio of 2.17 bits per quad and bit per vertex for
simple quadrilateral meshes and bit rates of 1.84 bits per polygon and
1.85 bits per vertex for the simple hybrid triangle-quad meshes |
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Paper Nr.: |
116 |
Title: |
APPROXIMATE G1 CUBIC SURFACES FOR DATA APPROXIMATION |
Author(s): |
Yingbin Liu and Stephen Mann |
Abstract: |
This
paper presents a piecewise cubic approximation method with approximate
$G^1$ continuity. For a given triangular mesh of points with arbitrary
topology, one cubic triangular B\'ezier patch surface is constructed.
The resulting surfaces have $G^1$ continuity at the vertex points, but
only requires approximate $G^1$ continuity along the
macro-patch boundaries so as to lower the patch degree. While our
scheme cannot generate the surfaces in as high quality as Loop's sextic
scheme, they are of half the polynomial degree, and of far better shape
quality than the results of interpolating split domain schemes. |
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Paper Nr.: |
120 |
Title: |
CONTROL POLYGON BASED TEXTURE SYNTHESIS ON BIQUADRATIC BĒZIER RATIONAL SURFACES |
Author(s): |
Rupesh N. Shet, H. E. Bez and E. A. Edirisinghe |
Abstract: |
Existing
texture synthesis algorithms fail to deliver effectively in application
areas where progressive rendering of texture is required. To provide a
practical solution to this problem we propose a novel algorithm for
progressive-texture synthesis on surfaces, which makes use of the
Embedded Zero-tree of Wavelet (EZW) idea proposed by Shapiro et al.,
1993 which is capable of prioritising the coefficients of a DWT
decomposed image according to their visual significance. We demonstrate
the use of the proposed algorithm on texturing a single biquadratic
surface and two smoothly joined biquadratic surfaces. It is further
shown that the proposed texture synthesis approach on Bézier patches
allows the algorithm's general use in texture synthesis on many common
surface topologies and can be generalised for arbitrarily shaped
surfaces. We provide experimental results to prove the effectiveness of
the proposed approach, when synthesising textures of regular, irregular
and stochastic nature. Further experimental results are provided to
illustrate the practical use of the proposed texture synthesis
algorithm in resource constrained application domains. |
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Paper Nr.: |
122 |
Title: |
GEOMETRICAL DEGENERACY REMOVAL BY VIRTUAL DISTURBANCES - An Application to Surface Reconstruction from Point Slice Samples |
Author(s): |
Oscar Ruiz, Eliana Vasquez, Sebastian Peña and Miguel Granados |
Abstract: |
In
surface reconstruction from slice samples (typical in medical imaging,
coordinate measurement machines, stereolithography, etc.) the available
methods attack the geometrical and topological aspects or a combination
of these. Topological methods classify the events occurred in the
2-manifold between two consecutive slices. Geometrical methods
synthesize the surface based on local proximity of contours in
consecutive slices. Many of these methods work with modifications of
Voronoi - Delaunay (VD) techniques, applied on slices i and i+1.
Superimposed 2D Voronoi Diagrams VDi and VDi+1 (used in surface
reconstruction) present topological problems if, for example, a site of
VDi lies on an site or an edge of VDi+1. The usual treatment of this
problem in literature is to apply a geometrical disturbance to either
VDi or VDi+1, thus eliminating the degeneracy. Recent works seek to
quantify the amount of the disturbance applied in relation to the
probability distribution of the event “change in the topology of VD”.
In this article, in contrast, virtual disturbances are proposed and
implemented, which allow for the application of subsequent steps of the
algorithm at hand (in this case, tetrahedra construction for surface
reconstruction) regardless of to the geometrical exception. Tetrahedra
(or any other downstream constructs) can then be instantiated as per
non-degenerate conditions. Although this method is applied for surface
reconstruction, it gives insight as to how to circumvent degeneracies
in procedures based on VD methods.
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Paper Nr.: |
123 |
Title: |
VISUALIZING MULTIPLE SCALAR FIELDS ON A SURFACE |
Author(s): |
Mohammed Mostefa Mesmoudi, Leila De Floriani and Paola Magillo |
Abstract: |
In (Mesmoudi et al., 2007b), the authors presented a theoretical visualization technique, called Atmosphere
Upper Bound Level (AUBL) that allows to a scalar field to be visualized on a surface. They showed how
this visualization technique can be used to extract the morphology of the scalar field and how can be used
in other applications. In this paper, we present our experimental results obtained from the implementation of
AUBL technique. Furthermore, we generalize the AUBL concept to a new visualization technique that allows a
graphical representation of more than one scalar field defined on the surface. This later technique that we call
Generalized AUBL (GAUBL), has the advantage to be interactive and displays the scalar fields separately and
uses transparencies for comparison purposes or displays them simultaneously to highlight the dependencies
and interactions between scalar fields. As a special case, a multi-valued scalar field can be handled by GAUBL. |
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Paper Nr.: |
124 |
Title: |
GPU-BASED NORMAL MAP GENERATION |
Author(s): |
Jesus Gumbau, Carlos Gonzalez and Miguel Chover |
Abstract: |
This
work presents a method for the generation of normal maps from two
polygonal models: a very detailed one with a high polygonal density,
and a coarser one which will be used for the real-time rendering. This
method generates the normal map of the high resolution model which can
be applied to the coarser model to improve its shading. The normal maps
are completely generated on the graphics hardware. |
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Paper Nr.: |
126 |
Title: |
HAPCO:
REAL TIME SIMULATION OF INTERACTION BETWEEN DEFORMABLE OBJECTS WITH
HAPTIC FEEDBACK FOR SOLVING FRICTION MULTIPLE CONTACTS |
Author(s): |
Nadjet Talbi, Pierre Joli, Zhi-Qiang Feng and Abderrahmane Kheddar |
Abstract: |
In
this paper we present HapCo, a real time physics-based simulator of
interaction between deformable objects with haptic force feedback for
scenarios involving friction multiple contacts. The discrete modeling
of the elastic bodies is achieved by the Finite Element Method (FEM).
In real time, the rigid displacements are applied to an elastic object
by means of a PHANTOM desktop. A force is computed and returned to this
haptic device when a collision occurs with a second clamped elastic
solid. This force feedback takes into account the linear elasticity
laws and the friction contact laws (Signorini and Coulomb) of the
elastic bodies in contact. So, we introduce two algorithms to calculate
efficiently the friction multi-contact forces occurring between two
deformable objects. These two algorithms are based on the bi-potential
formulation of the contact laws, offering the control of the solution
at each contact point through a unique operator of projection as well
as a better force feedback stability . According to the rendering
visual feedback given, the elastic deformations of the bodies computed
by the Finite Element Method look physically realistic. |
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Paper Nr.: |
145 |
Title: |
AN EXTENSION TO THE BEZIER SUB-DIVISION METHOD TO COMPLETELY APPROXIMATE CURVES AND SURFACES |
Author(s): |
Andreas Savva, Vasso Stylianou and George Portides |
Abstract: |
Sub-division
splines generate a number of new control points calculated fron the old
control points. Both control polygons/grids define the same
curve/surface. At each iteration the resulting new points are much
greater in number than the old points and lie nearer to the actual
curves. After a number of iterations, the generated points lie on the
actual curve, very close to each other, and by displaying them on a
computer screen the result is a smooth curve/surface. This paper
describes a method, which is an extension to the Bezier sub-division
method, where the resulting curve is an approximation curve which
interpolates only the first and the last control points. The method is
also derived for surfaces and some results are illustrated. |
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Paper Nr.: |
149 |
Title: |
A PEN AND PAPER METAPHOR FOR ORCHID MODELING |
Author(s): |
Burkhard Wuensche, Glen McCord, Beryl Plimmer, Greg Gilbert and Christian Hirsch |
Abstract: |
The creation of 3D computer models is an essential task for many applications in science, engineering and arts
and is frequently performed by untrained users. In many cases speed and simplicity of the modeling process is
more important than matching the geometry of the modeled object exactly. Sketch-based modeling has been
suggested as an important tool for such applications.
In this paper we take the pen and paper metaphor a step further and introduce a paper sculpting metaphor.
Using these techniques we present an efficient and effective tool for orchid modeling. We discuss the inherent
properties of orchid flowers and use them to develop constraints for representing the complex surface shapes
of orchids with simple 2D sketches. Surface details are added using noise functions.
Additional surface modifications are possible using the paper sculpting metaphor. By computing inherent
bending axis from the skeleton of a sketched 2D shape the user is able to warp leaf-like structures like if they
were cut from a piece of paper. The intuitive object manipulation of our tool means that an otherwise complex
model can be rapidly created by an inexperienced, non-artistic user in a short period of time. |
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Paper Nr.: |
187 |
Title: |
BEYOND GRAPHICS: INFORMATION - An Overview of Infovis Practices in the Field of the Architectural Heritage |
Author(s): |
J. Y. Blaise and I. Dudek |
Abstract: |
Understanding
and representing the evolution of architectural artefacts over time
requires a careful examination of heterogeneous, questionable pieces of
data. Accordingly, our position is that computer graphics can and will
support such investigation if and only if they are designed, above all,
as information visualisation disposals (may the visual result be
realistic or not). But contemporary practices often fail to reach this
goal. In this paper, we propose possible explanations, and argue why we
believe the problem has more to do with a lack of appropriate
methodology than with technologies. As an answer, we introduce a global
methodological framework that claims to be at the intersection of
figurative architectural representation and of information
visualisation. We finally back up this claim by presenting past and
contemporary examples showing there has been a bridge between the above
mentioned fields, a bridge that we today need to rebuild with or
against computer technologies. |
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Area 2 - Rendering
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Paper Nr.: |
11 |
Title: |
FINE ARTS EDUTAINMENT- The Amateur Painter |
Author(s): |
João Rodrigues, Daniel Almeida, Samuel Nunes, João Carvalho, Vera Brito and Hans du Buf |
Abstract: |
A
new scheme for painterly rendering (NPR) has been developed. This
scheme is based on visual perception, in particular the multi-scale
line/edge representation in the visual cortex. The Amateur Painter
(TAP) is the user interface on top of the rendering scheme. It allows
to (semi)automatically create paintings from photographs, with
different types of brush strokes and colour manipulations. In contrast
to similar painting tools, TAP has a set of menus that reflects the
procedure followed by a normal painter. In addition, menus and options
have been designed such that they are very intuitive, avoiding a jungle
of sub-menus with options from image processing that children and
laymen do not understand. Our goal is to create a tool that is
extremely easy to use, with the possibility that the user becomes
interested in painting techniques, styles, and fine arts in general. |
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Paper Nr.: |
58 |
Title: |
FROM VOLUME SPLATTING TO RAYCASTING - A Smooth Transition |
Author(s): |
Guillaume Gilet, Jean-Michel Dischler and Luc Soler |
Abstract: |
Splatting-based
methods are well suited to render large hierarchical structured or
unstructured point-based volumetric datasets.
However, as for most object-order volume rendering methods, one major
problem still remains the processing of huge amount
of elements usually necessary to represent highly detailed densely
sampled datasets, which can lead to poor performance. Resampling into
3D textures to apply hardware-based raycasting is a common way of
improving framerate in such cases but often with a certain precision
loss related to limited texture memory. Switching between these two
rendering techniques is interesting in order to keep the advantages of
both and has thus been proposed before, but not in a smooth and
hierarchical manner. In this paper, we show that for most point-based
volumetric datasets, some parts of the model can be rendered more
efficiently with a texture-based method, whereas other parts can be
rendered as usual using splatting. We address the issue of providing a
smooth hierarchical transition between the two methods using a
data-dependent approach based on a per-pixel ray-driven rendering
scheme. In practice, our transition scheme allows users a good control
of the performance/quality trade-off. Through a comparison with
standard hierarchical EWA splatting, we show that our smooth transition
can lead to an improvement of framerate without introducing visual
inconsistencies or artifacts. |
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Paper Nr.: |
80 |
Title: |
GENERIC BRDF SAMPLING - A Sampling Method for Global Illumination |
Author(s): |
Rosana Montes, Carlos Ureña, Ruben Garcia and Miguel Lastra |
Abstract: |
This
paper introduces a new BRDF sampling method with reduced variance,
which is based on a hierarchical adaptive parameterless PDF. This PDF
is based also on rejection sampling with a bounded average number of
trials, even in regions where the BRDF does exhibit high variations.
Our algorithm works in an appropiate way with both physical and
analytical reflectance models. Reflected directions are sampled by
using importance sampling of the BRDF times the cosine term. This fact
improves computation of reflected radiance when Monte-Carlo integration
is used in Global Illumination. Test images have been obtained by using
a Monte-Carlo rendering system, and they show reduced variance as
compared with those obtained by other known techniques. |
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Paper Nr.: |
81 |
Title: |
TIME-VARYING MULTIMODAL VOLUME RENDERING WITH 3D TEXTURES |
Author(s): |
Pascual Abellán, Sergi Grau and Dani Tost |
Abstract: |
In this paper, we propose a rendering method for multimodal and
time-varying data based on 3D texture mapping. Our method takes as
input two registered voxel models: one with static data and the other
with time-varying values. It visualizes the fusion of data through
time steps of different sizes, forward and backward. At each frame we
use one 3D texture for each modality. We compute and compose a set of
view-aligned texture slices. For each texel of a slice, we perform a
fetch to each 3D texture and realize fusion and shading using a
fragment shader. We codify the two shading transfer functions on
auxiliary 1D textures. Moreover, the weight of each modality in
fusion is not constant but defined through a 2D fusion transfer
function implemented as a 2D texture. We benefit from frame-to-frame
coherence to avoid reloading the time-varying data texture at each
frame. Instead, we update it at each frame using a 2D texture that
run-length encodes the variation of property values through time. The
3D texture updating is done entirely on the GPU, which significantly
speeds up rendering. Our method is fast and versatile and it provides
a good insight into multimodal data. |
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Paper Nr.: |
89 |
Title: |
OBJECTIVE QUALITY SELECTION FOR HYBRID LOD MODELS |
Author(s): |
Tom Jehaes, Wim Lamotte and Klaas Tack |
Abstract: |
The
problem of rendering large virtual 3D environments at interactive
framerates has traditionally been solved by using polygonal
Level-of-Detail (LoD) techniques, for which either a series of discrete
models or one progressive model were determined during preprocessing.
At runtime, several metrics such as distance, projection size and scene
importance are used to scale the objects to such a resolution that a
target framerate is maintained in order to provide a satisfactory user
experience. In recent years however, image-based techniques have
received a lot of interest from the research community because of their
ability to represent complex models in a compact way, thereby also
decreasing the time needed for rendering. One of the questions however
that should be given some more consideration is when to switch from
polygonal rendering to image-based rendering. In this paper we explore
this topic further and provide a solution using an objective image
quality metric which tries to optimize render quality. We test the
presented solution on both desktop and mobile systems. |
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Paper Nr.: |
90 |
Title: |
QUASI-CONVOLUTION PYRAMIDAL BLURRING |
Author(s): |
Martin Kraus |
Abstract: |
Efficient
image blurring techniques based on the pyramid algorithm can be
implemented on modern graphics hardware; thus, image blurring with
arbitrary blur width is possible in real time even for large images.
However, pyramidal blurring methods do not achieve the image quality
provided by convolution filters; in particular, the shape of the
corresponding filter kernel varies locally, which potentially results
in objectionable rendering artifacts. In this work, a new analysis
filter is designed that significantly reduces this variation for a
particular pyramidal blurring technique. Moreover, an efficient
implementation for programmable graphics hardware is presented. The
proposed method is named "quasi-convolution pyramidal blurring" since
the resulting effect is very close to image blurring based on a
convolution filter for many applications.
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Paper Nr.: |
99 |
Title: |
A DIRECT VOLUME RENDERING FRAMEWORK FOR THE INTERACTIVE EXPLORATION OF HIGHER-ORDER AND MULTIFIELD DATA |
Author(s): |
Felix Manke and Burkhard Wünsche |
Abstract: |
Direct
Volume Rendering is a popular method for displaying volumetric data
sets without generating intermediate representations. The technique is
most frequently applied to scalar data and few specialized techniques
exist for visualizing higher-order data, such as tensor fields,
directly. This is a serious limitation because progress in medical
imaging, satellite technology and numerical simulations has made
higher-order and multifield data sets a common entity in medicine,
science and engineering.
In this paper we present a framework for the interactive exploration of
complex data sets using direct volume rendering. This is achieved by
applying modern SE design technologies to modularize the direct volume
rendering pipeline and by exploiting the latest advances in graphics
hardware and shading languages to modify rendering effects and to
compute derived data sets at runtime.
We discuss how the framework can be used to mimic the latest
specialized direct volume rendering algorithms and to interactively
explore and gain new insight into high-order and multifield data sets.
The capabilities of the framework are demonstrated by two simple case
studies and the efficiency and effectiveness of the framework is
evaluated. |
|
Paper Nr.: |
104 |
Title: |
REAL-TIME VIEW-DEPENDENT VISUALIZATION OF REAL WORLD GLOSSY SURFACES |
Author(s): |
Claus B. Madsen, Bjarne K. Mortensen and Jens R. Andersen |
Abstract: |
A
technique for real-time visualization of glossy surfaces is presented.
The technique is aimed at recreating the view-dependent appearance of
glossy surfaces under some fixed illumination conditions. The
visualized surfaces can be actual real world surfaces or they can be
surfaces for which the appearance is precomputed with a global
illumination renderer. The approach taken is to image to surface from a
large number of viewpoints
distributed over the viewsphere. From these images the reflected
radiance in different direction is sampled and a parameterized model is
fitted to these radiance samples. Two different models are explored: a
very low parameter model inspired by the Phong reflection model, and a
general Spherical Harmonics model. It is concluded that the Phong-based
model is best suited for this type of application. |
|
Paper Nr.: |
107 |
Title: |
A GENERALIZATION APPROACH FOR 3D VIEWING DEFORMATIONS OF SINGLE-CENTER PROJECTIONS |
Author(s): |
Matthias Trapp and Jürgen Döllner |
Abstract: |
This
paper presents a novel image-based approach to efficiently generate
real-time non-planar projections of arbitrary 3D scenes such as
panorama and fish-eye views. The real-time creation of such projections
has a multitude of applications, e.g., in geovirtual environments and
in augmented reality. Our rendering technique is based on dynamically
created cube map textures in combination with shader programs that
calculate the specific projections. We discuss two different approaches
to create such cubemaps and introduce possible optimizations. Our
technique can be applied within a single rendering pass, is easy to
implement, and exploits the capability of modern programmable graphics
hardware completely. Further, we present an approach to customize and
combine different planar as well as non-planar projections. We have
integrated our technique into an existing real-time rendering framework
and demonstrate its performance on large scale datasets such as virtual
3D city and terrain models. |
|
Paper Nr.: |
110 |
Title: |
SUGGESTIVE CONTOURS OVER POINT-SET IMPLICITS |
Author(s): |
João Proença, Joaquim Jorge and Mario Costa Sousa |
Abstract: |
We present a system that combines large point-set implicit surfaces with fast line-based rendering. We devised
a new process for extracting suggestive contours quickly by using particles scattered throughout the surface to
identify areas of interest, followed by clustering and line-fitting. Furthermore, we improve on state-of-the-art
methods for extracting silhouettes and feature-lines by harnessing the descriptive power of the surface representation.
This provides heuristics for fast determination of curvature and allows for the local regeneration of
shape-depicting line elements after editing operations. While visual examples illustrate the high quality of the
drawings obtained with our application, as well as the high detail it can provide for more complex models,
run-times show comparatively higher performance over similar approaches for the same number of points. |
|
Paper Nr.: |
128 |
Title: |
A
Psychophysical Study of Foveal Gradient Based Selective RenderingA
PSYCHOPHYSICAL STUDY OF FOVEAL GRADIENT BASED SELECTIVE RENDERING |
Author(s): |
Veronica Sundstedt |
Abstract: |
High-fidelity
rendering of complex scenes at interactive rates is one of the primary
goals of computer graphics. Since high-fidelity rendering is
computationally expensive, perceptual strategies such as visual
attention have been explored to achieve this goal. Inattentional
Blindness (IB) experiments have shown that observers conducting a task
can fail to see an object, although it is located within the foveal
region (2°). However,
previous attention based algorithms assumed that IB would be restricted
to the area outside the foveal region, selectively rendering the areas
around task-related objects in high quality and the surrounding areas
in lower quality. This paper describes a
psychophysical forced-choice preference experiment assessing if
participants, performing a task or free-viewing animations, would fail
to notice rendering quality degradation within the foveal region. The
effect of prior knowledge on the level of perceived
quality is also studied. The study involves 64 participants in four
conditions: performing a task, or free-viewing a scene, while being
naive or informed about assessing rendering quality. Our results show
that participants fail to notice the additional reduction in quality,
decreasing the overall computation 13 times. There was also a
significant difference in the results if free-viewing participants were
informed. |
|
Paper Nr.: |
140 |
Title: |
DISPLACEMENT PATCHES FOR GPU-ORIENTED VIEW-DEPENDENT RENDERING |
Author(s): |
Yotam Livny, Gilad Bauman and Jihad El-Sana |
Abstract: |
In
this paper we present a new approach for interactive view-dependent
rendering of large polygonal datasets, which relies on advanced
features of modern graphics hardware. Our preprocessing algorithm
starts by generating a simplified representation of the input mesh. It
then builds a multiresolution hierarchy for the simplified model. For
each face in the hierarchy, it generates and assigns a displacement map
that resembles the original surface represented by that face. At
runtime, the multiresolution hierarchy is used to select a coarse
view-dependent level-of-detail representation, which is sent to the
graphics hardware. The GPU then refines the coarse representation by
replacing each face with a planar patch, which is elevated according to
the assigned displacement map. Experimental results show that our
implementation achieves quality images at high rates. |
|
Paper Nr.: |
183 |
Title: |
REAL-TIME MIXED REALITY WITH GPU TECHNIQUES |
Author(s): |
Tobias Franke and Yvonne Jung |
Abstract: |
In
this paper, we propose a combination of modern GPU-based methods that
are able to generate high-quality, interactive real-time rendering for
augmented and mixed reality applications. We also present a new
approach to estimate surface reflection functions and materials from
images using genetic algorithms. |
|
Paper Nr.: |
195 |
Title: |
TOWARDS PROBE-LESS AUGMENTED REALITY - A Position Paper |
Author(s): |
Claus B. Madsen and Michael Nielsen |
Abstract: |
The
main problem area for Augmented Reality is ensuring that the
illumination of the virtual objects is continuously consistent with the
illumination in the real scene. State of the art in the area typically
requires the real scene illumination conditions be captured as a High
Dynamic Range environment map of the scene. The environment map is then
used for shading and shadowing. Handling the real and the virtual
shadows and their interaction is the single most difficult aspect. This
paper presents a completely different approach to determining the
illumination conditions in the real scene. Based on an assumption that
the scene is outdoor we automatically detect shadows in the image and
use this information to determine the ratio of sky irradiance to sun
irradiance. We then present how to convert this information into
radiance levels for both the sky and the sun. When combined with a
computation of the Sun's position based on date, time and information
about position on the Earth, we arrive at a full illumination model
applicable for rendering virtual objects into real scenes.
|
|
|
Area 3 - Animation and Simulation
|
Paper Nr.: |
56 |
Title: |
MODELING AND SIMULATING MOBILE ROBOT ENVIRONMENTS |
Author(s): |
Oliver Kutter, Christian Hilker, Alexander Simon and Bärbel Mertsching |
Abstract: |
According
to the requirements of our ongoing research on algorithms of robot
vision and manipulation, we present a newly developed simulation
framework for mobile robot environments called SIMORE. A dynamic 3D
environment has been created in which simulated robots, sensors and
actors can be manipulated. Multiple methods to operate a robot are
provided including control by manual input devices, graphical user
interface and program commands. The interface to the simulator is
transparent so that the control commands can be directly transferred to
the real hardware platform after successful simulation tests. In
addition to the 3D graphics engine the simulator has a physics engine
to guarantee a correct physical behavior. The modeling of all objects
(visual and dynamic) can be done in modeling software. Simulations can
run either in an offline mode, in which actions are predefined, or in
an online mode, where an operator can directly manipulate the simulated
system by manual input devices. The simulation framework is designed to
be modular and flexible in order to allow future extensions and
enhancements such as inclusion of additional sensors. |
|
Paper Nr.: |
72 |
Title: |
DIRECTABLE AND STYLIZED HAIR SIMULATION |
Author(s): |
Yosuke Kazama, Eiji Sugisaki and Shigeo Morishima |
Abstract: |
Creating
natural looking hair motion is considered as one of the most difficult
and time consuming tasks in CG animation so that it has been
challenging. A detailed physics model is an essential to create
convincing hair animation. However, hair animation created by a
detailed hair dynamics might not be desired result for creators. For
this reason, both detailed and editable hair simulation system is
required in contemporary CG world. In this paper, therefore, we propose
External Force Field (EFF) for hair motion constructed by motion
capture system. Furthermore, we develop a system for editing the
obtained hair motion. First, we capture an environment around a subject
by motion capture system, and then define EFF. Secondly, we develop a
hair motion editing system based on EFF for creating creator-oriented
hair animation. Consequently, our editing system enables creators to
create desired hair animation intuitively without a physical
discontinuity. |
|
Paper Nr.: |
79 |
Title: |
EFFICIENT INVERSE KINEMATICS ALGORITHM BASED ON CONFORMAL GEOMETRIC ALGEBRA - Using Reconfigurable Hardware |
Author(s): |
Dietmar Hildenbrand, Holger Lange, Florian Stock and Andreas Koch |
Abstract: |
This paper presents a very efficient
approach for algorithms developed based on conformal geometric
algebra using reconfigurable hardware. We use the inverse kinematics
of the arm of a virtual human as an example, but we are convinced
that this approach can be used in a wide field of computer animation
applications. We describe the original algorithm on a very high
geometrically intuitive level as well as the resulting optimized
algorithm based on symbolic calculations of a computer algebra
system. The main focus then is to demonstrate our approach for the
hardware implementation of this algorithm leading to a very
efficient implementation. |
|
Paper Nr.: |
109 |
Title: |
A FULLY GPU-IMPLEMENTED RIGID BODY SIMULATOR |
Author(s): |
Álvaro del Monte, Roberto Torres, Pedro J. Martín and Antonio Gavilanes |
Abstract: |
In
this paper we study how to implement a fully GPU-based rigid body
simulator by programming shaders for every phase of the simulation. We
analyze the pros and cons of different approaches, and point out the
bottlenecks we have detected. We also apply the developed techniques to
two case studies, comparing them with the analogous versions running on
CPU. |
|
Paper Nr.: |
112 |
Title: |
DTW-CURVE FOR CLASSIFICATION OF LOGICALLY SIMILAR MOTIONS |
Author(s): |
Yang Yuedong, Zhao Qinping, Hao Aiminand Wu Weihe |
Abstract: |
Logical
classification of motion data is the precondition of motion editing and
behaviour recognition. The typical distance metrics of sequences can
not identify logical relation between motions well. Based on the
traditional DTW distance metrics, this paper proposes strategies
bidirectional DTW and segment DTW, both of which could improve the
robustness of identifying logically related motions, and then proposes
a DTW-Curve method which is used to compare the logical similarity
between the motions. The generation of DTW-Curve includes three steps.
Firstly, motions should be normalized to remove the global translation
and align the global orientation. Secondly, motions are resampled to
cluster local frames and remove redundant frames. Finally, DTW-Curve is
generated under the control of different thresholds. DTW-Curve may
produce many statistical properties, which could be used to
unsupervised logical classification of motions. We propose two types of
statistical properties, and classify motion data by using hierarchical
clustering procedure. The experiment results demonstrate that the
logical classification based on DTW-Curve has better classification
performance and robustness. |
|
Paper Nr.: |
117 |
Title: |
INTERACTIVE RECONSTRUCTION AND VISUALIZATION OF DYNAMIC 3D ULTRASOUND DATA SETS |
Author(s): |
Timo Ropinski, Borislav Petkov, Larissa Fabritz and Klaus Hinrichs |
Abstract: |
In
this paper we describe techniques which have been developed in order to
interactively visualize dynamic 3D ultrasound (US) volume data sets
acquired using a small animal 2D US scanner. The 2D frames are acquired
at different spatial positions and gated based on the ECG signal. For
the reconstruction process a user interface is specified, which allows
the user to select 2D frames acquired during different ECG phases at
different spatial locations. Thus it is possible to reconstruct and
visualize a volumetric model based on several 2D frames for different
phases of the heart cycle. To improve the interactive visualization, we
facilitate filtering techniques, which have been implemented on the GPU. |
|
Paper Nr.: |
132 |
Title: |
RAY-TRACED COLLISION DETECTION FOR DEFORMABLE BODIES |
Author(s): |
Everton Hermann, François Faure and Bruno Raffin |
Abstract: |
This
paper presents a new approach to collision detection and modeling
between deformable volumetric bodies. It allows deep intersections
while alleviating the difficulties of distance field update.
A ray is shot from each surface vertex in the direction of the inward
normal. A collision is detected when the first intersection belongs to
an inward surface triangle of another body.
A contact force between the vertex and the matching point is then
created. Experiments show that this approach is fast and more robust
than traditional proximity-based collisions. |
|
Paper Nr.: |
134 |
Title: |
REALISTIC RAIN RENDERING |
Author(s): |
Yoshiki Mizukami, Katsuhiro Sasaki and Katsumi Tadamura |
Abstract: |
This
paper proposes a method for rendering realistic three-dimensional
raining scene.
This proposed method gives two main contributions to rendering raining
scene. The first one is to propose a simple model that deals with
temporal-spatial localities such as wind effect, density and intensity
of rainfall, and raindrop brightness, so as to represent environmental
conditions that differs on a scene-to-scene basis.
The other one is to propose a raindrop trajectory computing method
whose computation load immunes to the number of raindrop, wind effect
and complicated camera movement. Due to the above-mentioned
contributions, the proposed method can represent essential aspects in
raining scene, such as spatial changes of rain in urban canyon or
temporal changes due to the moving wisp of rain. |
|
Paper Nr.: |
153 |
Title: |
SIMULATION OF CONSTRUCTION PROCESSES WITHIN VIRTUAL ENVIRONMENTS |
Author(s): |
Alcínia Zita Sampaio and Pedro Gameiro Henriques |
Abstract: |
Three-dimensional
geometric models have been used to present architectural and
engineering works, showing their final configuration. But, when the
clarification of a detail or the constitution of a construction step in
needed, these models are not appropriate because they do not allow the
observation of the construction activity. Models that could present
dynamically changes of the building geometry are a good support on
education in civil engineering domain. Techniques of geometric
modelling and virtual reality were used to obtain interactive models
that could visually simulate the construction activity. The
applications explain the construction work of a cavity wall and a
bridge. These models allow the visualization of the physical
progression of the work following a planned construction sequence, the
observation of details of the form of every component of the works and
support the study of the type and method of operation of the equipment
applied in the construction. The models present distinct advantage as
educational aids in first-degree courses in Civil Engineering. The use
of Virtual Reality techniques in the development of educational
applications brings new perspectives to the teaching of subjects
related to the field of civil construction |
|
Paper Nr.: |
194 |
Title: |
AUTOMATIC COMPOSITION OF DRAMATIC MOVEMENT - Analysis and Algorithm for Creating Contemporary Dance Sequences |
Author(s): |
Asako Soga and Bin Umino |
Abstract: |
We
have developed an automatic composition system for contemporary dance
by using 3DCG animation. Our goal is to develop some useful tools in
dance education such as creation-support system for teachers and
self-study system for students. Our approach is not creating natural
connection but creating conceptual sequences. As a result of previous
experiment, we recognize the connecting method is not so important for
contemporary dancers. We try to create short sequences that have
dramatic stories according to the structure of Chinese poetry in
ancient times. The basic movements of contemporary dance are classified
and analyzed. The algorithm for automatic composition is integrated to
create utilitarian choreographies for lessons. This system is valuable
for online virtual dance experimentation and exploration by teachers
and choreographers involved in creative practices, improvisation,
creative movement, or dance composition. |
|
|
Area 4 - Interactive Environments
|
Paper Nr.: |
44 |
Title: |
LOCALIZATION IN AN INTERACTIVE SYSTEM |
Author(s): |
Juan J. Jiménez, Francisco R. Feito and Rafael J. Segura |
Abstract: |
The
localization of the nearest parts of an object to a device is usually
solved by means of a proximity measurement of each one of the features
that form this object to the device. In order to perform this
efficiently, hierarchical decompositions of the space or of the object
are used, so that the features of objects are classified into several
types of cells, usually rectangular. In this paper we propose a
solution based on
the classification of a set of points located on the device in a
spatial decomposition named tetra-tree. Using this type of spatial
decomposition gives us several qualitative properties that allow us a
more realistic and intuitive visual interaction. In order to show these
properties we have compared an interaction system based on tetra-trees
to one based on octrees. |
|
Paper Nr.: |
61 |
Title: |
IMAGE QUALITY IN IMAGE-BASED REPRESENTATIONS OF REAL-WORLD ENVIRONMENTS - Perceived Smoothness of Viewpoint Transitions |
Author(s): |
Filippo Speranza, Akshay Bhatia and Robert Laganière |
Abstract: |
In
this study, we investigated the effect of viewpoint density and speed
of motion on perceived smoothness of viewpoint transitions. The effect
of viewpoint density was examined for two types of viewer motion:
forward and lateral motion. In both cases, we found that perceived
smoothness varies with viewpoint density. We also found the number of
viewpoints required to maintain a certain level of perceived smoothness
varies inversely with speed of movement represented. |
|
Paper Nr.: |
73 |
Title: |
A SIP SPATIAL AUDIO SERVER FOR THE EVE PLATFORM |
Author(s): |
Ch. Bouras, V. Triglianos and Th. Tsiatsos |
Abstract: |
When
it comes to 3D Virtual Environments it is well known that 3D sound is
of great importance to the whole interactive experience. The percept of
sound is a major counterpart for the eyesight, since it describes the
location, the momentum and the attitude towards the listener, of each
surrounding entity. The sound can offer precision of spatial perception
that cannot be achieved by the eye itself. Thus the support of 3D
surround sound of high fidelity is mandatory for a 3D Virtual platform.
The evolution of Internet telephony led to the introduction of new
session establishment and management protocols. The most important of
them, the Session Initiation Protocol (SIP), is a robust, lightweight
reliable and fast application-layer control (signaling) protocol that
is highly adopted for creating, modifying and terminating sessions.
This protocol can be of extreme importance in establishing audio
sessions for multi-user platforms. This paper presents the work done
for developing a SIP 3D spatial audio server for a multi-user virtual
environments platform, called EVE, in order to support 3D spatial audio |
|
Paper Nr.: |
74 |
Title: |
A MULTI-CAMERA FRAMEWORK FOR INTERACTIVE VIDEO GAMES |
Author(s): |
Tom Cuypers, Cedric Vanaken, Yannick Francken, Frank Van Reeth and Philippe Bekaert |
Abstract: |
We
present a framework that allows for a straightforward development of
multi-camera controlled interactive video games. Compared to
traditional gaming input devices, cameras provide players with many
degrees of freedom and a natural kind of interaction. The use of
cameras can even obsolete the need for special clothing or other
tracking devices. This partly accounted for the success of the
currently popular single-camera video games like the Sony Eyetoy.
However, these games are fairly limited in the use of 3D scene
information. Using multi-camera setups, this limitation can be
surpassed, but typically many different image processing and computer
vision techniques are involved. Our framework divides multi-camera
based games into basic algorithms that are easily combinable into
several sequentially executed stages. Therefore the amount of effort to
develop new games can significantly be reduced. The capabilities of our
framework are demonstrated with a number of conceptual games, proving
that multi-camera controlled video games can be created with
off-the-shelf hardware. |
|
Paper Nr.: |
84 |
Title: |
A 3D SIMULATION OF A GAME OF BILLIARDS USING A HAPTIC DEVICE |
Author(s): |
Lucio Tommaso De Paolis, Giovanni Aloisio and Marco Pulimeno |
Abstract: |
Recently
the computer entertainment technology has generated a great deal of
interest among researchers and developers who have recognized the
potential to create new and exciting forms of human computer
interaction. Performance improvements in graphics hardware and the
diffusion of the low cost haptic interfaces have made it possible to
visualize complex virtual environments and provided opportunities to
interact with these in a more realistic way. In this paper a Virtual
Reality application of a game of billiards is presented. By means of a
commercial haptic interface a force feedback is provided, thus
rendering the interaction realistic and exciting to the user; the
introduction of the force feedback allows the user to actually feel the
contact between cue and ball. The virtual environment has been built
using the development environment XVR and rigid body dynamics have been
simulated utilizing the ODE library. |
|
Paper Nr.: |
119 |
Title: |
GENERATING HUMAN INTERACTIVE BEHAVIOURS USING THE WINDOWED VITERBI ALGORITHM |
Author(s): |
Yue Zheng, Yulia Hicks, Dave Marshall and Darren Cosker |
Abstract: |
In
this paper, we propose a new approach for generating interactive
behaviours for virtual characters, namely the windowed Viterbi
algorithm, capable of doing so in real-time. Consequently, we compare
the performance of the standard Viterbi algorithm and the windowed
Viterbi algorithm within our system. Our system tracks and analyses the
behaviour of a real person in video input and produces a fully
articulated three dimensional (3D) character interacting with the
person in the video input. Our system is model-based. Prior to
tracking, we train a collection of dual Hidden Markov Model (HMM) on 3D
motion capture (MoCap) data representing a number of interactions
between
two people. Then using the dual HMM, we generate a moving virtual
character reacting to (the motion of) a real person. In this article,
we present the detailed evaluation of using the windowed Viterbi
algorithms within our system, and show that our approach
is suitable for generating interactive behaviours in real-time.
|
|
Paper Nr.: |
121 |
Title: |
A TOOL SUPPORTING MODEL BASED USER INTERFACE DESIGN IN 3D VIRTUAL ENVIROMENTS |
Author(s): |
Joan De Boeck, Chris Raymaekers and Karin Coninx |
Abstract: |
Although
interactive virtual environments (IVE) have the capability to offer
intuitive and easy to use interfaces, their creation is often a long
and expensive process, in which specialists play a key role. The
–Project–
approach investigates how the use of high-level specifications may help
to overcome this problem: instead of coding an IVE using a low level
programming language, high-level models are used. As such a modelbased
process combines a series of models containing a mixture of manual and
automatic processes. The usefulness of a model based process relies on
available tool support. Supporting the –Project– process, this paper
introduces –Tool–. This tool has been used in order to develop a series
of demonstrators, all based on
real-life cases. From this experience, the –Project– approach and more
particular –Tool– have proven to be useful to develop interactive
virtual environments using high-level specifications. |
|
Paper Nr.: |
125 |
Title: |
A DIYD (DO IT YOURSELF DESIGN) SYSTEM FOR VEHICLE DESIGN BASED ON 3D VISUALIZATION AND ONTOLOGIES |
Author(s): |
Lambros Makris, Nikolaos Karatzoulis, Dimitrios Tzovaras and Evangelos Bekiaris |
Abstract: |
The
customization level of vehicles is growing in order to deal with
increasing user needs. Web browsers are becoming the focal point of
vehicle customization, forming personalized market places where users
can select and preview various setups. However the state of the art for
the completion of the transaction is still very much characterized by a
face-to-face sales situation. Direct sales over the internet, without
sales person contacts, are still a small segment of the market, of only
a few percent, for European manufacturers. This paper presents an
Intelligent DIY e-commerce system for vehicle design, based on 3D
Visualization and Ontologies that aims at enabling a suitable
representation of products with the most realistic possible
visualization outcome in order to help prospective customers in their
decision. The platform, designed for the vehicle sector, includes all
the practicable electronic commerce variants and its on-line product
configuration process is controlled by an ontology that was created
using the OWL Web Ontology Language. |
|
Paper Nr.: |
127 |
Title: |
ANIMATING AND RENDERING VIRTUAL HUMANS - Extending X3D for Real Time Rendering and Animation of Virtual Characters |
Author(s): |
Yvonne Jung |
Abstract: |
In
this paper, we focus on the different aspects of real time
visualization and animation of realistic virtual characters. The common
goal was to come up with solutions based on the concepts of the open
ISO standard X3D and if necessary to propose generalized extensions to
the standard.
First we describe the high level control language PML and its
implementation, which is also suitable for non-graphics experts. Then
we focus on realistic rendering, how X3D must be extended to allow
special effects and realization of novel rendering algorithms,
including skin and emotion rendering.
Next we explain the challenges of dynamics related to virtual
characters covering play-back and blending of pre-defined animations,
online simulation of locomotion and last but not least hair simulation. |
|
Paper Nr.: |
129 |
Title: |
AUGMENTING 3D CITY MODELS WITH VISUALIZATION OF REAL-TIME METEOROLOGICAL PHENOMENA |
Author(s): |
Frank Steinicke, Jörg Mensmann, Klaus Hinrichs, Jan de Buhr, Kai Rothaus and Antonio Krüger |
Abstract: |
General
interest in visualizations of digital 3D city models is growing
rapidly, and several applications are already available that display
such models very realistically. Many authors have emphasized the
importance of the effects of realistic illumination for computer
generated images, and this applies especially to the context of 3D city
visualization. However, current 3D city visualization applications
rarely implement techniques for achieving realistic illumination, in
particular the effects caused by current weather-related phenomena. At
most, some geospatial visualization systems render artificial
skies—sometimes with a georeferenced determination of the sun
position—to give the user the impression of a real sky. However, such
artificial renderings are not sufficient for real simulation purposes.
In this paper we present techniques to augment visualizations of
digital 3D city models with real-time display of georeferenced
meteorological phenomena. For this purpose we retrieve weather
information from different sources, i. e., real-time images from
cameras and radar data from web-based weather services, and we use this
information in the rendering process for realistic visualization of
different weather-related issues, such as clouds, rain, fog, etc. Our
approach is not limited to a specific setup, and we have evaluated the
results in a user study presented in this paper. |
|
Paper Nr.: |
130 |
Title: |
A FRAMEWORK FOR 4-D BIOMEDICAL IMAGE PROCESSING, VISUALIZATION AND ANALYSIS |
Author(s): |
Matteo Campana, Barbara Rizzi, Camilo Melani, Paul Bourgine, Nadine Peyrieras and Alessandro Sarti |
Abstract: |
Today,
studies on biological systems are often realized acquiring, processing
and analyzing 4-D image datasets. In this paper we present a software
framework that aims at providing support for managing multidimensional
biological images, designing and validating new image processing
algorithms, and analyzing processed images through different
visualization techniques. Finally we present a real scenario where the
framework has been used for the segmentation of biological cell
membranes and nuclei imaged from live zebrafish embryos. |
|
Paper Nr.: |
141 |
Title: |
AN INTERACTIVE 3D VISUALIZATION MODEL BY LIVE STREAMING FOR REMOTE SCIENTIFIC VISUALIZATION |
Author(s): |
Eriko Touma, Satomi Hara, Mari Kurumi, Yuri Shirakawa, Chisato Ishikawa, Masami Takata, Takeshi Horinouchi and Kazuki Joe |
Abstract: |
Recent improvement of high-end GPUs has made it possible to perform real-time 3D visualization
such as volume rendering and 3D contour plot for scientific data locally.
A web browser based remote 3D visualization by visualization servers is attractive,
but data transfer overhead prevents from performing interactive operations.
We propose an interactive remote 3D visualization model by live streaming for geophysical fluids research.
In this model, we use live streaming flash media for the web browser based operations keeping minimum quality of data analysis
and minimum bit rate for live streaming of flash media.
Preliminary experiments with a prototype system validate the effectiveness of our proposing model. |
|
Paper Nr.: |
179 |
Title: |
A SCIENCE OF INTERACTION - A Multidimensional Canvas |
Author(s): |
Robert Spence |
Abstract: |
A
recently proposed search for a science of interaction will involve the
creation of a multidimensional canvas composed of many features:
complex perceptual and cognitive processes, the many approaches to
interaction design, the many models of interaction and the vast range
of interaction modalities. In any attempt to meet this challenge this
paper urges emphasis on precise definitions, especially for
visualization and interaction, and reports the results of an
exploratory study. |
|
Paper Nr.: |
185 |
Title: |
SPLITTING THE SCENE GRAPH - Using Spatial Relationship Graphs Instead of Scene Graphs in Augmented Reality |
Author(s): |
Florian Echtler, Manuel Huber, Daniel Pustka, Peter Keitler and Gudrun Klinker |
Abstract: |
Scene graphs have been a core element
of 3D graphics since the publication of Inventor. However, in
Virtual and Augmented Reality applications, 3D graphics
are often interleaved with and controlled by real-world data
provided by pose trackers, cameras and other kinds of sensors.
In such a setup, the generalized concept of a Spatial Relationship
Graph (SRG) might be better suited as an underlying data structure
to describe the application and its components. In this paper, we
will give an overview of the SRG concept, describe its difference
to a scene graph and provide an example AR application built upon
a SRG-based tracking library. |
|
Paper Nr.: |
189 |
Title: |
REGISTRATION APPROACHES FOR AUGMENTED REALITY - A Crucial Aspect for Successful Industrial Application |
Author(s): |
Katharina Pentenrieder and Peter Meier |
Abstract: |
In the past years, a variety of Augmented Reality (AR)-based applications were created, aiming to support
industrial processes. Although these first demonstrator applications or prototypes cover all parts of the industrial
product process - design, planning and production, service and maintenance - only a few of them actually
turned into established and applied solutions. Reasons for this lack of acceptance are - amongst others - their
insufficient usability and accuracy.
One crucial step in the accuracy chain for an Augmented Reality system is the registration of real and virtual
world. This paper presents different approaches for industrial registration, which are being investigated in the
context of an Augmented Reality based factory planning application. The resulting toolbox promises to be
helpful and valuable for general application in industrial AR. To support the choice for an optimal registration
method for a given scenario, the toolbox is currently being evaluated according to usability and accuracy
criteria. The current state of this evaluation as well as future planned studies are also outlined here. |
|
Paper Nr.: |
191 |
Title: |
THE
FUTURE OF PARALLEL COMPUTING: GPU VS CELL - General Purpose Planning
against Fast Graphical Computation Architectures, which is the Best
Solution for General Purposes Computation? |
Author(s): |
Luca Bianchi, Riccardo Gatti and Luca Lombardi |
Abstract: |
Complex
models require high performance computing (HPC) which means Parallel
Computing. That is a fact. The question we try to address in this paper
is "which is the best suitable solution for HPC contexts such as
rendering? Will it be possible to use it in General Purpose
elaborations?" We start from these questions and analyze two different
approaches, IBM CELL and the well known GPGPU, showing how changing our
minds and breaking some assumptions can lead to unexpected results and
open a whole set of new possibilities. We talk about rendering, but
quickly move slightly towards general purpose computation, because many
algorithms used in Visual Simulations are not only referred to
rendering issues but to a wider range of problems. |
|
|
Art, Science and Technology, Virtual tools for Cultural Heritage
|
Paper Nr.: |
115 |
Title: |
VIRTUAL
RESTORATION OF A MEDIEVAL POLYCHROME SCULPTURE - Experimentation,
Modelization, Validation and Visualization in Spectral Ray-tracing |
Author(s): |
Sylvain Dumazet, Patrick Callet and Ariane Genty |
Abstract: |
A pluridisciplinary work always in progress
involving 3D digitization, simulation, rapid prototyping,
virtual restoration of a french medieval sculpture is presented. This work is
led in the framework of a general collaboration between three academic labs,
industrial partners and Cultural institutions. The main purpose is to virtually represent a polychrome statue
of the XIIIth century in high quality spectral rendering, to simulate
its visual and original appearance at that period. The complete process used
throughout all the phases of the project mainly involves optical devices that
ensure no physical contact with the museum object.
This article describes the complete chain of engineering resources and the main
models we used for accomplishing our objective. From 3D capture without contact
to plaster replica, the complete process will be described and illustrated with
images and objects during the conference. Some sequences extracted from the
didactic and scientific movies produced will also be presented. |
|
Paper Nr.: |
143 |
Title: |
VIRTUAL ART GALLERY TOOL |
Author(s): |
Pedro Miguel Semião and Maria Beatriz Carmo |
Abstract: |
This
paper describes a set of two applications comprising the Virtual Art
Gallery tool: the Space Picker application and the Virtual Exhibition
Builder application. The purpose of this tool is to allow users to
interactively create a virtual exhibition of artworks in a pre-built
virtual model. We use X3D for the models and Java with Xj3D for the
display and handling. The works of art are handled through a MySQL
database. The solution is entirely based in free soft-ware. |
|
Paper Nr.: |
165 |
Title: |
STUDYING USERS’ ACCEPTABILITY TOWARDS 3D IMMERSIVE ENVIRONMENTS - Virtual Tours: A Case Study |
Author(s): |
Karina Rodriguez Echavarria, Craig Moore, David Morris, David Arnold, A. Delaney and R. Heath |
Abstract: |
If
information is considered the key in today’s information society, then
museums and heritage sites are of critical importance as they are
places for knowledge to be shared and experienced by individuals. For
this reason, presenting and distributing information through ICT forms
could play a critical role for the museum in order to empower the
public in their understanding of the past. The view of using ICT
contextualisation mechanisms, such as 3D immersive virtual environment,
in museums and heritage sites is explored in this research. Hence, this
paper describes efforts towards exploring the acceptability of the
interfaces and interaction techniques for Virtual Tours. We acknowledge
the difficulty of the task as 3D immersive environment do not have
defined interfaces nor visitor are believed to have replicable
experiences. However, we believe that a significant amount of studies
of this type might provide some answers to a field full of expectations
but not
enough experience in the ICT field. |
|
Paper Nr.: |
170 |
Title: |
UNDERWATER PHOTOGRAMMETRY FOR ARCHAEOLOGY, THE VENUS PROJECT FRAMEWORK |
Author(s): |
P. Drap, D. Scaradozzi, P. Gambogi and F. Gauch |
Abstract: |
This
article describes on-going developments of the VENUS European Project
(Virtual ExploratioN of Underwater Sites, http://www.venus-project.eu)
concerning the first mission to sea in Pianosa Island, Italy in October
2006. The VENUS project aims at providing scientific methodologies and
technological tools for the virtual exploration of deep underwater
archaeological sites. The VENUS project will improve the accessibility
of underwater sites by generating thorough and exhaustive 3D records
for virtual exploration. In this paper we focus on the underwater
photogrammetric approach used to survey the archaeological site of
Pianosa. After a brief presentation of the archaeological context we
shall see the calibration process in such a context. The next part of
this paper is dedicated to the survey: it is divided into two parts: a
DTM of the site (combining acoustic bathymetry and photogrammetry) and
a specific artefact plotting dedicated to the amphorae present on the
site. |
|
Paper Nr.: |
192 |
Title: |
GPU SPECTRAL VIEWER - A Tool for an Enhanced Colorimetric Perspective of Cultural Heritage |
Author(s): |
Denis Pitzalis, Philippe Colantoni, Ruven Pillay and Genevieve Aitken |
Abstract: |
During the EU IST project CRISATEL the consortium made around one hundred multispectral scans of paintings
conserved in several museums. The high resolution images obtained allow us to not only have an accurate
colour image but also to perform in depth quantitative scientific measures in the colour structure of works of
art.
One of these paintings in particular required special attention. It was Leonardo da Vinci’s “Mona Lisa”. In
order to study it a special GPU oriented software was developed. In this paper we will present how the GPU
computation and the computer vision can deliver the high performance and the analysis capability required to
study complex and subtle works of art. |
|
|
Multimedia Collaborative Virtual Environments
|
Paper Nr.: |
144 |
Title: |
A REVIEW OF COLLABORATIVE VIRTUAL ENVIRONMENT (CVE) EVALUATION METHODOLOGIES |
Author(s): |
Thrasyvoulos Tsiatsos and Konstantinidis Andreas |
Abstract: |
This paper presents several methodologies concerning the evaluation of
Collaborative Virtual Environments (CVEs). In doing so, the authors aim
to compensate for the absence of a CVE evaluating standard, with the
goal of aid-ing future evaluators in their task. Initially, the paper
discusses the general benefits of CVEs and computer supported
collaborative learning (CSCL). Based on the examined research it
continues with suggested evaluation criteria and the division of
evaluation into partitions. Following that, we discuss rec-ommended
evaluator profiles and data mining practices. The paper concludes with
a description of appropriate data analysis procedures. In the final
section, some closing remarks are made and future work is discussed. |
|
Paper Nr.: |
161 |
Title: |
DEVELOPMENT OF THE VIRTUAL ELA®-HOUSE |
Author(s): |
Milán Horváth, Csaba Dániel, Jacqueline Stark and Cecília Sik Lanyi |
Abstract: |
In
this paper, the rationale for the development and the process of
creating the Virtual ELA®-House are described. The Virtual ELA®-House
is an innovative therapy program designed for use with clients with
language and speech disorders and/or with other cognitive
neuropsychological disorders, which result from brain damage, e.g.
aphasia, apraxia of speech, neglect, etc. The Virtual Reality setting
is chosen as a modern and relevant therapy setting which imitates real
everyday life scenarios. Computer supported cognitive and language
therapy allows for repetitive application in the clinical and home
setting which is necessary for learning to take place. The advantages
of employing a software program based on a Virtual Environment, in
particular the ELA®-virtual house, are discussed. |
|
Paper Nr.: |
163 |
Title: |
PRESENTING INTERACTIVE MULTIMEDIA DOCUMENTS WITHIN VIRTUAL ENVIRONMENTS |
Author(s): |
Paulo N. M. Sampaio, Laura M. Rodriguez Peralta and João Pedro D. Pereira |
Abstract: |
Different
languages and tools have been used for the modelling and building
Virtual Reality applications which can be applied in different domains.
These tools are each time more sophisticated providing means for the
author of a 3D environment to build his model intuitively. However,
these languages and APIs used for building virtual environments are
still limited when it comes to integrate multimedia content inside
these applications. This paper presents a generic and extensible
solution for the presentation of integrated Interactive Multimedia
Documents within Virtual Reality applications. |
|
Paper Nr.: |
164 |
Title: |
EMBEDDING MULTIMEDIA CONTENT WITHIN VIRTUAL ENVIRONMENTS - The OGRE Approach |
Author(s): |
Paulo N. M. Sampaio, Roberto Ivo C. de Freitas and Gonçalo Nuno P. Cardoso |
Abstract: |
Most of the tools and languages for modeling Virtual Reality
environments, such as VRML, X3D, Java3D, etc. do not provide means of
describing the synchronized presentation of multimedia content inside
these environments. Multimedia has demonstrated its capabilities of
motivating users and capturing their attention, which is an interesting
characteristic when we want to provide a higher degree of immersion
inside Virtual Reality applications. This paper presents a robust and
generic solution for the integrated presentation of different kinds of
media objects inside virtual environments based on the Graphical Engine
OGRE. |
|
Paper Nr.: |
172 |
Title: |
A MODEL FOR WIRELESS SENSOR NETWORKS SUPPORTED COOPERATIVE WORK |
Author(s): |
Lina M. Pestana Leão de Brito and Laura M. Rodríguez Peralta |
Abstract: |
Collaboration
is essential to Wireless Sensor Networks due to the typical resource
limitations of the sensor nodes. In fact, the main functions of the
network cannot be accomplished without collaboration among sensor
nodes. Most of the work found in literature only focuses a specific
type of collaboration, associated with the accomplishment of a certain
task, such as signal processing, computing, routing, etc. In this
paper, we present a graph-based model of cooperative work for WSNs.
This model is called Wireless Sensor Networks Supported Cooperative
Work (WSNSCW) and considers the specific requirements of the WSNs. |
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