---
OA_place: publisher
_id: '20551'
abstract:
- lang: eng
text: "The space of codimension-2 shapes, such as curves in 3D and surfaces in 4D,
is an infinite-dimensional manifold. This thesis explores geometric structures
and dynamics on this space, with emphasis on their implications for physics, particularly
hydrodynamics.\r\n\r\nOur investigation ranges from theoretical studies of infinite-dimensional
symplectic and prequantum geometry to numerical computation of the time evolution
of shapes. The thesis presents four main contributions.\r\n\r\nIn the first part,
we introduce implicit representations of codimension-2 shapes using a class of
complex-valued functions, and prove that the space of these implicit representations
forms a prequantum bundle over the codimension-2 shape space. This reveals a new
geometric interpretation of the canonical symplectic structure on the codimension-2
shape space.\r\n\r\nIn the second part, we use implicit representations to develop
a simulation method for the dynamics of space curves. To handle chaotic systems
such as vortex filaments in hydrodynamics, we exploit the infinite degrees of
freedom, hidden in both the configuration and dynamics of implicit representations.\r\n\r\nIn
the third part, we introduce new symplectic structures on the space of space curves,
which generalize the only previously known symplectic structure on this space,
allowing for new Hamiltonian dynamics of space curves.\r\n\r\nIn the fourth part,
we apply a symplectic viewpoint to a differential geometric problem with practical
applications. We derive a new area formula for spherical polygons via prequantization. "
acknowledged_ssus:
- _id: CampIT
acknowledgement: "Projects contained in this thesis were financially supported in
part by the\r\nEuropean Research Council with grants 1. ERC Consolidator Grant 101045083
CoDiNA,\r\nand 2. the European Union’s Horizon 2020 research and innovation programme
under grant\r\nagreement No. 638176."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Sadashige
full_name: Ishida, Sadashige
id: 6F7C4B96-A8E9-11E9-A7CA-09ECE5697425
last_name: Ishida
orcid: 0000-0002-3121-3100
citation:
ama: Ishida S. Symplectic-prequantum structures and dynamics on the codimension-2
shape space. 2025. doi:10.15479/AT-ISTA-20551
apa: Ishida, S. (2025). Symplectic-prequantum structures and dynamics on the
codimension-2 shape space. Institute of Science and Technology Austria. https://doi.org/10.15479/AT-ISTA-20551
chicago: Ishida, Sadashige. “Symplectic-Prequantum Structures and Dynamics on the
Codimension-2 Shape Space.” Institute of Science and Technology Austria, 2025.
https://doi.org/10.15479/AT-ISTA-20551.
ieee: S. Ishida, “Symplectic-prequantum structures and dynamics on the codimension-2
shape space,” Institute of Science and Technology Austria, 2025.
ista: Ishida S. 2025. Symplectic-prequantum structures and dynamics on the codimension-2
shape space. Institute of Science and Technology Austria.
mla: Ishida, Sadashige. Symplectic-Prequantum Structures and Dynamics on the
Codimension-2 Shape Space. Institute of Science and Technology Austria, 2025,
doi:10.15479/AT-ISTA-20551.
short: S. Ishida, Symplectic-Prequantum Structures and Dynamics on the Codimension-2
Shape Space, Institute of Science and Technology Austria, 2025.
corr_author: '1'
date_created: 2025-10-27T10:28:52Z
date_published: 2025-10-31T00:00:00Z
date_updated: 2026-04-07T12:02:23Z
day: '31'
ddc:
- '516'
degree_awarded: PhD
department:
- _id: GradSch
- _id: ChWo
doi: 10.15479/AT-ISTA-20551
ec_funded: 1
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creator: sishida
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language:
- iso: eng
month: '10'
oa: 1
oa_version: Published Version
page: '141'
project:
- _id: 2533E772-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '638176'
name: 'Big Splash: Efficient Simulation of Natural Phenomena at Extremely Large
Scales'
- _id: 34bc2376-11ca-11ed-8bc3-9a3b3961a088
grant_number: '101045083'
name: Computational Discovery of Numerical Algorithms for Animation and Simulation
of Natural Phenomena
publication_identifier:
isbn:
- 978-3-99078-070-1
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
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- id: '12846'
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status: public
- id: '12431'
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- id: '17361'
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status: public
- id: '20580'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Christopher J
full_name: Wojtan, Christopher J
id: 3C61F1D2-F248-11E8-B48F-1D18A9856A87
last_name: Wojtan
orcid: 0000-0001-6646-5546
- first_name: Albert
full_name: Chern, Albert
last_name: Chern
title: Symplectic-prequantum structures and dynamics on the codimension-2 shape space
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: dissertation
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2025'
...
---
OA_place: publisher
_id: '19630'
abstract:
- lang: eng
text: "This thesis consists of three chapters, each corresponding to one publication.
While each of these projects tackles a topic in a different area of research,
they all share a common thread in the type of topological structure they handle
- a partition of space into volumes separated by interfaces that meet in non-manifold
junctions.\r\n\r\nIn Chapter 2, we study clusters of soap bubbles from a simulation
perspective. In particular, we develop a surface-only algorithm that couples large
scale motion and shape deformation of soap bubble clusters with the small scale
evolution of the thin film's thickness, which is responsible for visual phenomena
like surface vortices, Newton's interference patterns, capillary waves, and deformation-dependent
rupturing of films in a foam. We model film thickness as a reduced degree of freedom
in the Navier-Stokes equations and from them derive three sets of equations governing
normal and tangential motion of the soap film surface, as well as the evolution
of the thin film thickness. We discretize these equations on a non-manifold triangle
mesh, extending and adapting operators to handle complex topology. We also present
an incompressible fluid solver for 2.5D films and an advection algorithm for convecting
fields across non-manifold surface junctions. Our simulations enhance bubble solvers
with additional effects caused by convection, rippling, draining, and evaporation
of the thin film.\r\n\r\nIn Chapter 3, we introduce a multi-material non-manifold
mesh-based surface tracking algorithm that converts mesh defects, such as overlaps,
self-intersections, and inversions into topological changes. Our algorithm generalizes
prior work on manifold surface tracking with topological changes: it preserves
surface features like mesh-based methods, and it robustly handles topological
changes like level set methods. Our method also offers improved efficiency and
robustness over the state of the art. We demonstrate the effectiveness of the
approach on a range of examples, including complex soap film simulations, such
as those presented in Chapter 2, but with an order of magnitude more interacting
bubbles than what we could achieve before, and Boolean unions of non-manifold
meshes consisting of millions of triangles.\r\n\r\nLastly, in Chapter 4, we utilize
developments in the theory of random geometric complexes facilitated by observations
from Discrete Morse theory. We survey the methods and results obtained with this
new approach, and discuss some of its shortcomings. We use simulations to illustrate
the results and to form conjectures, getting numerical estimates for combinatorial,
topological, and geometric properties of weighted and unweighted Delaunay mosaics,
their dual Voronoi tessellations, and the Alpha and Wrap complexes contained in
the mosaics."
acknowledged_ssus:
- _id: ScienComp
acknowledgement: The project in Chapter 2 has received funding from the European Research
Council (ERC) under the European Union's Horizon 2020 research and innovation programme
under grant agreement No. 638176. The project in Chapter 3 was funded in part by
the European Union (ERC-2021-COG 101045083 CoDiNA). The project in Chapter 4 has
received funding from the European Research Council (ERC) under the European Union's
Horizon 2020 research and innovation programme (grant agreements No 78818 Alpha
and No 638176). It was also partially supported by the DFG Collaborative Research
Center TRR 109, 'Discretization in Geometry and Dynamics', through grant no. I02979-N35
of the Austrian Science Fund (FWF). Thank you for providing funds to support my
work.
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Peter
full_name: Synak, Peter
id: 331776E2-F248-11E8-B48F-1D18A9856A87
last_name: Synak
citation:
ama: Synak P. Methods for fluid simulation, surface tracking, and statistics of
non-manifold structures. 2025. doi:10.15479/AT-ISTA-19630
apa: Synak, P. (2025). Methods for fluid simulation, surface tracking, and statistics
of non-manifold structures. Institute of Science and Technology Austria. https://doi.org/10.15479/AT-ISTA-19630
chicago: Synak, Peter. “Methods for Fluid Simulation, Surface Tracking, and Statistics
of Non-Manifold Structures.” Institute of Science and Technology Austria, 2025.
https://doi.org/10.15479/AT-ISTA-19630.
ieee: P. Synak, “Methods for fluid simulation, surface tracking, and statistics
of non-manifold structures,” Institute of Science and Technology Austria, 2025.
ista: Synak P. 2025. Methods for fluid simulation, surface tracking, and statistics
of non-manifold structures. Institute of Science and Technology Austria.
mla: Synak, Peter. Methods for Fluid Simulation, Surface Tracking, and Statistics
of Non-Manifold Structures. Institute of Science and Technology Austria, 2025,
doi:10.15479/AT-ISTA-19630.
short: P. Synak, Methods for Fluid Simulation, Surface Tracking, and Statistics
of Non-Manifold Structures, Institute of Science and Technology Austria, 2025.
corr_author: '1'
date_created: 2025-04-29T09:39:34Z
date_published: 2025-04-29T00:00:00Z
date_updated: 2026-04-16T08:29:34Z
day: '29'
ddc:
- '519'
- '006'
degree_awarded: PhD
department:
- _id: ChWo
- _id: GradSch
doi: 10.15479/AT-ISTA-19630
ec_funded: 1
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creator: cchlebak
date_created: 2025-04-30T14:02:25Z
date_updated: 2025-04-30T14:02:25Z
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file_size: 60670543
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content_type: application/pdf
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date_created: 2025-04-30T14:02:42Z
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language:
- iso: eng
month: '04'
oa: 1
oa_version: Published Version
page: '106'
project:
- _id: 2533E772-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '638176'
name: 'Big Splash: Efficient Simulation of Natural Phenomena at Extremely Large
Scales'
- _id: 34bc2376-11ca-11ed-8bc3-9a3b3961a088
grant_number: '101045083'
name: Computational Discovery of Numerical Algorithms for Animation and Simulation
of Natural Phenomena
- _id: 266A2E9E-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '788183'
name: Alpha Shape Theory Extended
- _id: 2533E772-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '638176'
name: 'Big Splash: Efficient Simulation of Natural Phenomena at Extremely Large
Scales'
- _id: 2561EBF4-B435-11E9-9278-68D0E5697425
call_identifier: FWF
grant_number: I02979-N35
name: Persistence and stability of geometric complexes
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '8135'
relation: part_of_dissertation
status: public
- id: '17219'
relation: part_of_dissertation
status: public
- id: '8384'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Christopher J
full_name: Wojtan, Christopher J
id: 3C61F1D2-F248-11E8-B48F-1D18A9856A87
last_name: Wojtan
orcid: 0000-0001-6646-5546
title: Methods for fluid simulation, surface tracking, and statistics of non-manifold
structures
type: dissertation
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2025'
...
---
OA_place: publisher
_id: '18301'
abstract:
- lang: eng
text: Physics simulation in computer graphics can bring triangle meshes into topologically
invalid states. The method in this thesis contributed to Heiss-Synak* and Kalinov*
et al. [2024] who devised a non-manifold hybrid surface tracker—a surface tracker
that repairs explicit non-manifold triangle meshes with the help of the implicit
domain. Specifically, this thesis provides an algorithm for filling the holes
that are left after removing problematic parts of the mesh.
alternative_title:
- ISTA Master's Thesis
article_processing_charge: No
author:
- first_name: Arian
full_name: Etemadihaghighi, Arian
id: 36cea3aa-f38e-11ec-8ae0-c65ae6f6098f
last_name: Etemadihaghighi
citation:
ama: Etemadi A. Filling the holes of non-manifold self-intersecting meshes for implicit
topology changes in surface tracking. 2024. doi:10.15479/at:ista:18301
apa: Etemadi, A. (2024). Filling the holes of non-manifold self-intersecting
meshes for implicit topology changes in surface tracking. Institute of Science
and Technology Austria. https://doi.org/10.15479/at:ista:18301
chicago: Etemadi, Arian. “Filling the Holes of Non-Manifold Self-Intersecting Meshes
for Implicit Topology Changes in Surface Tracking.” Institute of Science and Technology
Austria, 2024. https://doi.org/10.15479/at:ista:18301.
ieee: A. Etemadi, “Filling the holes of non-manifold self-intersecting meshes for
implicit topology changes in surface tracking,” Institute of Science and Technology
Austria, 2024.
ista: Etemadi A. 2024. Filling the holes of non-manifold self-intersecting meshes
for implicit topology changes in surface tracking. Institute of Science and Technology
Austria.
mla: Etemadi, Arian. Filling the Holes of Non-Manifold Self-Intersecting Meshes
for Implicit Topology Changes in Surface Tracking. Institute of Science and
Technology Austria, 2024, doi:10.15479/at:ista:18301.
short: A. Etemadi, Filling the Holes of Non-Manifold Self-Intersecting Meshes for
Implicit Topology Changes in Surface Tracking, Institute of Science and Technology
Austria, 2024.
corr_author: '1'
date_created: 2024-10-11T19:52:20Z
date_published: 2024-10-15T00:00:00Z
date_updated: 2026-04-07T13:02:36Z
day: '15'
ddc:
- '000'
degree_awarded: MS
department:
- _id: GradSch
- _id: ChWo
doi: 10.15479/at:ista:18301
file:
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creator: aetemadi
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date_created: 2024-10-24T14:34:54Z
date_updated: 2024-10-24T14:34:54Z
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keyword:
- surface tracking
- non-manifold
- hole-filling
- topology change
- multi-material
- solid-modeling
language:
- iso: eng
license: https://creativecommons.org/licenses/by-sa/4.0/
month: '10'
oa: 1
oa_version: Published Version
page: '39'
publication_identifier:
issn:
- 2791-4585
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '17219'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Christopher J
full_name: Wojtan, Christopher J
id: 3C61F1D2-F248-11E8-B48F-1D18A9856A87
last_name: Wojtan
orcid: 0000-0001-6646-5546
title: Filling the holes of non-manifold self-intersecting meshes for implicit topology
changes in surface tracking
tmp:
image: /images/cc_by_sa.png
legal_code_url: https://creativecommons.org/licenses/by-sa/4.0/legalcode
name: Creative Commons Attribution-ShareAlike 4.0 International Public License (CC
BY-SA 4.0)
short: CC BY-SA (4.0)
type: dissertation
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2024'
...
---
OA_place: publisher
_id: '12358'
abstract:
- lang: eng
text: "The complex yarn structure of knitted and woven fabrics gives rise to both
a mechanical and\r\nvisual complexity. The small-scale interactions of yarns colliding
with and pulling on each\r\nother result in drastically different large-scale
stretching and bending behavior, introducing\r\nanisotropy, curling, and more.
While simulating cloth as individual yarns can reproduce this\r\ncomplexity and
match the quality of real fabric, it may be too computationally expensive for\r\nlarge
fabrics. On the other hand, continuum-based approaches do not need to discretize
the\r\ncloth at a stitch-level, but it is non-trivial to find a material model
that would replicate the\r\nlarge-scale behavior of yarn fabrics, and they discard
the intricate visual detail. In this thesis,\r\nwe discuss three methods to try
and bridge the gap between small-scale and large-scale yarn\r\nmechanics using
numerical homogenization: fitting a continuum model to periodic yarn simulations,
adding mechanics-aware yarn detail onto thin-shell simulations, and quantitatively\r\nfitting
yarn parameters to physical measurements of real fabric.\r\nTo start, we present
a method for animating yarn-level cloth effects using a thin-shell solver.\r\nWe
first use a large number of periodic yarn-level simulations to build a model of
the potential\r\nenergy density of the cloth, and then use it to compute forces
in a thin-shell simulator. The\r\nresulting simulations faithfully reproduce expected
effects like the stiffening of woven fabrics\r\nand the highly deformable nature
and anisotropy of knitted fabrics at a fraction of the cost of\r\nfull yarn-level
simulation.\r\nWhile our thin-shell simulations are able to capture large-scale
yarn mechanics, they lack\r\nthe rich visual detail of yarn-level simulations.
Therefore, we propose a method to animate\r\nyarn-level cloth geometry on top
of an underlying deforming mesh in a mechanics-aware\r\nfashion in real time.
Using triangle strains to interpolate precomputed yarn geometry, we are\r\nable
to reproduce effects such as knit loops tightening under stretching at negligible
cost.\r\nFinally, we introduce a methodology for inverse-modeling of yarn-level
mechanics of cloth,\r\nbased on the mechanical response of fabrics in the real
world. We compile a database from\r\nphysical tests of several knitted fabrics
used in the textile industry spanning diverse physical\r\nproperties like stiffness,
nonlinearity, and anisotropy. We then develop a system for approximating these
mechanical responses with yarn-level cloth simulation, using homogenized\r\nshell
models to speed up computation and adding some small-but-necessary extensions
to\r\nyarn-level models used in computer graphics.\r\n"
acknowledged_ssus:
- _id: SSU
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Georg
full_name: Sperl, Georg
id: 4DD40360-F248-11E8-B48F-1D18A9856A87
last_name: Sperl
citation:
ama: 'Sperl G. Homogenizing yarn simulations: Large-scale mechanics, small-scale
detail, and quantitative fitting. 2022. doi:10.15479/at:ista:12103'
apa: 'Sperl, G. (2022). Homogenizing yarn simulations: Large-scale mechanics,
small-scale detail, and quantitative fitting. Institute of Science and Technology
Austria. https://doi.org/10.15479/at:ista:12103'
chicago: 'Sperl, Georg. “Homogenizing Yarn Simulations: Large-Scale Mechanics, Small-Scale
Detail, and Quantitative Fitting.” Institute of Science and Technology Austria,
2022. https://doi.org/10.15479/at:ista:12103.'
ieee: 'G. Sperl, “Homogenizing yarn simulations: Large-scale mechanics, small-scale
detail, and quantitative fitting,” Institute of Science and Technology Austria,
2022.'
ista: 'Sperl G. 2022. Homogenizing yarn simulations: Large-scale mechanics, small-scale
detail, and quantitative fitting. Institute of Science and Technology Austria.'
mla: 'Sperl, Georg. Homogenizing Yarn Simulations: Large-Scale Mechanics, Small-Scale
Detail, and Quantitative Fitting. Institute of Science and Technology Austria,
2022, doi:10.15479/at:ista:12103.'
short: 'G. Sperl, Homogenizing Yarn Simulations: Large-Scale Mechanics, Small-Scale
Detail, and Quantitative Fitting, Institute of Science and Technology Austria,
2022.'
corr_author: '1'
date_created: 2023-01-24T10:49:46Z
date_published: 2022-09-22T00:00:00Z
date_updated: 2026-04-16T08:31:54Z
day: '22'
ddc:
- '000'
- '620'
degree_awarded: PhD
department:
- _id: GradSch
- _id: ChWo
doi: 10.15479/at:ista:12103
ec_funded: 1
file:
- access_level: open_access
checksum: 083722acbb8115e52e3b0fdec6226769
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creator: cchlebak
date_created: 2023-01-25T12:04:41Z
date_updated: 2023-02-02T09:29:57Z
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- iso: eng
month: '09'
oa: 1
oa_version: Published Version
page: '138'
project:
- _id: 2533E772-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '638176'
name: 'Big Splash: Efficient Simulation of Natural Phenomena at Extremely Large
Scales'
publication_identifier:
isbn:
- 978-3-99078-020-6
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
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relation: part_of_dissertation
status: public
- id: '8385'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Christopher J
full_name: Wojtan, Christopher J
id: 3C61F1D2-F248-11E8-B48F-1D18A9856A87
last_name: Wojtan
orcid: 0000-0001-6646-5546
title: 'Homogenizing yarn simulations: Large-scale mechanics, small-scale detail,
and quantitative fitting'
type: dissertation
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2022'
...
---
OA_place: publisher
_id: '839'
abstract:
- lang: eng
text: 'This thesis describes a brittle fracture simulation method for visual effects
applications. Building upon a symmetric Galerkin boundary element method, we first
compute stress intensity factors following the theory of linear elastic fracture
mechanics. We then use these stress intensities to simulate the motion of a propagating
crack front at a significantly higher resolution than the overall deformation
of the breaking object. Allowing for spatial variations of the material''s toughness
during crack propagation produces visually realistic, highly-detailed fracture
surfaces. Furthermore, we introduce approximations for stress intensities and
crack opening displacements, resulting in both practical speed-up and theoretically
superior runtime complexity compared to previous methods. While we choose a quasi-static
approach to fracture mechanics, ignoring dynamic deformations, we also couple
our fracture simulation framework to a standard rigid-body dynamics solver, enabling
visual effects artists to simulate both large scale motion, as well as fracturing
due to collision forces in a combined system. As fractures inside of an object
grow, their geometry must be represented both in the coarse boundary element mesh,
as well as at the desired fine output resolution. Using a boundary element method,
we avoid complicated volumetric meshing operations. Instead we describe a simple
set of surface meshing operations that allow us to progressively add cracks to
the mesh of an object and still re-use all previously computed entries of the
linear boundary element system matrix. On the high resolution level, we opt for
an implicit surface representation. We then describe how to capture fracture surfaces
during crack propagation, as well as separate the individual fragments resulting
from the fracture process, based on this implicit representation. We show results
obtained with our method, either solving the full boundary element system in every
time step, or alternatively using our fast approximations. These results demonstrate
that both of these methods perform well in basic test cases and produce realistic
fracture surfaces. Furthermore we show that our fast approximations substantially
out-perform the standard approach in more demanding scenarios. Finally, these
two methods naturally combine, using the full solution while the problem size
is manageably small and switching to the fast approximations later on. The resulting
hybrid method gives the user a direct way to choose between speed and accuracy
of the simulation. '
acknowledgement: "ERC H2020 programme (grant agreement no. 638176)\r\nFirst of all,
let me thank my committee members, especially my supervisor, Chris\r\nWojtan, for
supporting me throughout my PhD. Obviously, none of this work would\r\nhave been
possible without you.\r\nFurthermore, Thank You to all the people who have contributed
to this work in various\r\nways, in particular Martin Schanz and his group for providing
and supporting the\r\nHyENA boundary element library, as well as Eder Miguel and
Morten Bojsen-Hansen\r\nfor (repeatedly) proof reading and providing valuable suggestions
during the writing\r\nof this thesis.\r\nI would also like to thank Bernd Bickel,
and all the members – past and present – of his\r\nand Chris’ research groups at
IST Austria for always providing honest and insightful\r\nfeedback throughout many
joint group meetings, as well as Christopher Batty, Eitan\r\nGrinspun, and Fang
Da for many insights into boundary element methods during our\r\ncollaboration.\r\nAs
only virtual objects have been harmed in the process of creating this work, I would\r\nlike
to acknowledge the Stanford scanning repository for providing the “Bunny” and\r\n“Armadillo”
models, the AIM@SHAPE repository for “Pierre’s hand, watertight”, and\r\nS. Gainsbourg
for the “Column” via Archive3D.net. Sorry for breaking these models\r\nin many different
ways.\r\n"
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: David
full_name: Hahn, David
id: 357A6A66-F248-11E8-B48F-1D18A9856A87
last_name: Hahn
citation:
ama: Hahn D. Brittle fracture simulation with boundary elements for computer graphics.
2017. doi:10.15479/AT:ISTA:th_855
apa: Hahn, D. (2017). Brittle fracture simulation with boundary elements for
computer graphics. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:th_855
chicago: Hahn, David. “Brittle Fracture Simulation with Boundary Elements for Computer
Graphics.” Institute of Science and Technology Austria, 2017. https://doi.org/10.15479/AT:ISTA:th_855.
ieee: D. Hahn, “Brittle fracture simulation with boundary elements for computer
graphics,” Institute of Science and Technology Austria, 2017.
ista: Hahn D. 2017. Brittle fracture simulation with boundary elements for computer
graphics. Institute of Science and Technology Austria.
mla: Hahn, David. Brittle Fracture Simulation with Boundary Elements for Computer
Graphics. Institute of Science and Technology Austria, 2017, doi:10.15479/AT:ISTA:th_855.
short: D. Hahn, Brittle Fracture Simulation with Boundary Elements for Computer
Graphics, Institute of Science and Technology Austria, 2017.
corr_author: '1'
date_created: 2018-12-11T11:48:47Z
date_published: 2017-08-14T00:00:00Z
date_updated: 2026-04-08T14:20:16Z
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call_identifier: H2020
grant_number: '638176'
name: 'Big Splash: Efficient Simulation of Natural Phenomena at Extremely Large
Scales'
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publication_status: published
publisher: Institute of Science and Technology Austria
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status: public
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full_name: Wojtan, Christopher J
id: 3C61F1D2-F248-11E8-B48F-1D18A9856A87
last_name: Wojtan
orcid: 0000-0001-6646-5546
title: Brittle fracture simulation with boundary elements for computer graphics
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abstract:
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text: "Computer graphics is an extremely exciting field for two reasons. On the
one hand,\r\nthere is a healthy injection of pragmatism coming from the visual
effects industry\r\nthat want robust algorithms that work so they can produce
results at an increasingly\r\nfrantic pace. On the other hand, they must always
try to push the envelope and\r\nachieve the impossible to wow their audiences
in the next blockbuster, which means\r\nthat the industry has not succumb to conservatism,
and there is plenty of room to\r\ntry out new and crazy ideas if there is a chance
that it will pan into something\r\nuseful.\r\nWater simulation has been in visual
effects for decades, however it still remains\r\nextremely challenging because
of its high computational cost and difficult artdirectability.\r\nThe work in
this thesis tries to address some of these difficulties.\r\nSpecifically, we make
the following three novel contributions to the state-of-the-art\r\nin water simulation
for visual effects.\r\nFirst, we develop the first algorithm that can convert
any sequence of closed\r\nsurfaces in time into a moving triangle mesh. State-of-the-art
methods at the time\r\ncould only handle surfaces with fixed connectivity, but
we are the first to be able to\r\nhandle surfaces that merge and split apart.
This is important for water simulation\r\npractitioners, because it allows them
to convert splashy water surfaces extracted\r\nfrom particles or simulated using
grid-based level sets into triangle meshes that can\r\nbe either textured and
enhanced with extra surface dynamics as a post-process.\r\nWe also apply our algorithm
to other phenomena that merge and split apart, such\r\nas morphs and noisy reconstructions
of human performances.\r\nSecond, we formulate a surface-based energy that measures
the deviation of a\r\nwater surface froma physically valid state. Such discrepancies
arise when there is a\r\nmismatch in the degrees of freedom between the water
surface and the underlying\r\nphysics solver. This commonly happens when practitioners
use a moving triangle\r\nmesh with a grid-based physics solver, or when high-resolution
grid-based surfaces\r\nare combined with low-resolution physics. Following the
direction of steepest\r\ndescent on our surface-based energy, we can either smooth
these artifacts or turn\r\nthem into high-resolution waves by interpreting the
energy as a physical potential.\r\nThird, we extend state-of-the-art techniques
in non-reflecting boundaries to handle spatially and time-varying background flows.
This allows a novel new\r\nworkflow where practitioners can re-simulate part of
an existing simulation, such\r\nas removing a solid obstacle, adding a new splash
or locally changing the resolution.\r\nSuch changes can easily lead to new waves
in the re-simulated region that would\r\nreflect off of the new simulation boundary,
effectively ruining the illusion of a\r\nseamless simulation boundary between
the existing and new simulations. Our\r\nnon-reflecting boundaries makes sure
that such waves are absorbed."
acknowledgement: "First and foremost I would like to thank Chris. I have been incredibly
lucky to have\r\nyou as my advisor. Your integrity and aspiration to do the right
thing in all walks of\r\nlife is something I admire and aspire to. I also really
appreciate the fact that when\r\nworking with you it felt like we were equals. I
think we had a very synergetic work\r\nrelationship: I learned immensely from you,
but I dare say that you learned a few\r\nthings from me as well. ;)\r\nNext, I would
like to thank my amazing committee. Hao, it was a fantastic\r\nexperience working
with you. You showed me how to persevere and keep morale\r\nhigh when things were
looking the most bleak before the deadline. You are an\r\nincredible motivator and
super fun to be around! Vladimir, thanks for the shared\r\nlunches and the poker
games. Sorry for not bringing them back when I got busy.\r\nAlso, sorry for embarrassing
you by asking about your guitar playing that one\r\ntime. You really are quite awesome!
Nils, one of the friendliest and most humble\r\npeople you will meet and a top notch
researcher to boot! Thank you for joining\r\nmy committee late!\r\nI would also
like to acknowledge the Visual Computing group at IST Austria\r\nfrom whom I have
learned so much. The excellent discussions we had in reading\r\ngroups and research
meetings really helped me become a better researcher!\r\nNext, I would like to thank
all the amazing people that I met during my PhD\r\nstudies, both at IST Austria,
in Vienna and elsewhere. "
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Morten
full_name: Bojsen-Hansen, Morten
id: 439F0C8C-F248-11E8-B48F-1D18A9856A87
last_name: Bojsen-Hansen
orcid: 0000-0002-4417-3224
citation:
ama: Bojsen-Hansen M. Tracking, correcting and absorbing water surface waves. 2016.
doi:10.15479/AT:ISTA:th_640
apa: Bojsen-Hansen, M. (2016). Tracking, correcting and absorbing water surface
waves. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:th_640
chicago: Bojsen-Hansen, Morten. “Tracking, Correcting and Absorbing Water Surface
Waves.” Institute of Science and Technology Austria, 2016. https://doi.org/10.15479/AT:ISTA:th_640.
ieee: M. Bojsen-Hansen, “Tracking, correcting and absorbing water surface waves,”
Institute of Science and Technology Austria, 2016.
ista: Bojsen-Hansen M. 2016. Tracking, correcting and absorbing water surface waves.
Institute of Science and Technology Austria.
mla: Bojsen-Hansen, Morten. Tracking, Correcting and Absorbing Water Surface
Waves. Institute of Science and Technology Austria, 2016, doi:10.15479/AT:ISTA:th_640.
short: M. Bojsen-Hansen, Tracking, Correcting and Absorbing Water Surface Waves,
Institute of Science and Technology Austria, 2016.
corr_author: '1'
date_created: 2018-12-11T11:50:16Z
date_published: 2016-07-15T00:00:00Z
date_updated: 2026-04-08T14:24:06Z
day: '15'
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supervisor:
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id: 3C61F1D2-F248-11E8-B48F-1D18A9856A87
last_name: Wojtan
orcid: 0000-0001-6646-5546
title: Tracking, correcting and absorbing water surface waves
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