7 Search Results for "Bl�mer, Johannes"

Document
Short Paper
DOI: 10.4230/LIPIcs.GIScience.2023.62
An Evaluation of the Impact of Ignition Location Uncertainty on Forest Fire Ignition Prediction Using Bayesian Logistic Regression (Short Paper)

Authors: David Röbl, Rizwan Bulbul, Johannes Scholz, Mortimer M. Müller, and Harald Vacik

Published in: LIPIcs, Volume 277, 12th International Conference on Geographic Information Science (GIScience 2023)

Abstract
This study investigates the impact of location uncertainty on the predictive performance of Bayesian Logistic Regression (BLR) for forest fire ignition prediction in Austria. Historical forest fire ignitions are used to create a dataset for training models with the capability to assess the general forest fire ignition susceptibility. Each recorded fire ignition contains a timestamp, the estimated location of the ignition and a radius defining the area within which the unknown true location of the ignition point is located. As the values of the predictive features are calculated based on the assumed location, and not the unknown true location, the training data is biased due to input uncertainties. This study is set to assess the impact of input data uncertainty on the predictive performance of the model. For this we use a data binning approach that splits the input data into groups based on their location uncertainty and use them later for training multiple BLR models. The predictive performance of the models is then compared based on their accuracy, area under the receiver operating characteristic curve (AUC) scores and brier scores. The study revealed that higher location uncertainty leads to decreased accuracy and AUC score, accompanied by an increase in the brier score, while demonstrating that the BLR model trained on a smaller high-quality dataset outperforms the model trained on the full dataset, despite its smaller size. The study’s contribution is to provide insights into the practical implications of location uncertainty on the quality of forest fire susceptibility predictions, with potential implications for forest risk management and forest fire documentation.
Cite as

David Röbl, Rizwan Bulbul, Johannes Scholz, Mortimer M. Müller, and Harald Vacik. An Evaluation of the Impact of Ignition Location Uncertainty on Forest Fire Ignition Prediction Using Bayesian Logistic Regression (Short Paper). In 12th International Conference on Geographic Information Science (GIScience 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 277, pp. 62:1-62:7, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{robl_et_al:LIPIcs.GIScience.2023.62,
  author =	{R\"{o}bl, David and Bulbul, Rizwan and Scholz, Johannes and M\"{u}ller, Mortimer M. and Vacik, Harald},
  title =	{{An Evaluation of the Impact of Ignition Location Uncertainty on Forest Fire Ignition Prediction Using Bayesian Logistic Regression}},
  booktitle =	{12th International Conference on Geographic Information Science (GIScience 2023)},
  pages =	{62:1--62:7},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-288-4},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{277},
  editor =	{Beecham, Roger and Long, Jed A. and Smith, Dianna and Zhao, Qunshan and Wise, Sarah},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.GIScience.2023.62},
  URN =		{urn:nbn:de:0030-drops-189576},
  doi =		{10.4230/LIPIcs.GIScience.2023.62},
  annote =	{Keywords: Forest Fire Prediction, Ignition Location Uncertainty, Bayesian Logistic Regression, Bayesian Inference, Probabilistic Programming}
}
Document
Short Paper
DOI: 10.4230/LIPIcs.GIScience.2023.63
Calculating Shadows with U-Nets for Urban Environments (Short Paper)

Authors: Dominik Rothschedl, Franz Welscher, Franziska Hübl, Ivan Majic, Daniele Giannandrea, Matthias Wastian, Johannes Scholz, and Niki Popper

Published in: LIPIcs, Volume 277, 12th International Conference on Geographic Information Science (GIScience 2023)

Abstract
Shadow calculation is an important prerequisite for many urban and environmental analyses such as the assessment of solar energy potential. We propose a neural net approach that can be trained with 3D geographical information and predict the presence and depth of shadows. We adapt a U-Net algorithm traditionally used in biomedical image segmentation and train it on sections of Styria, Austria. Our two-step approach first predicts binary existence of shadows and then estimates the depth of shadows as well. Our results on the case study of Styria, Austria show that the proposed approach can predict in both models shadows with over 80% accuracy which is satisfactory for real-world applications, but still leaves room for improvement.
Cite as

Dominik Rothschedl, Franz Welscher, Franziska Hübl, Ivan Majic, Daniele Giannandrea, Matthias Wastian, Johannes Scholz, and Niki Popper. Calculating Shadows with U-Nets for Urban Environments (Short Paper). In 12th International Conference on Geographic Information Science (GIScience 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 277, pp. 63:1-63:6, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{rothschedl_et_al:LIPIcs.GIScience.2023.63,
  author =	{Rothschedl, Dominik and Welscher, Franz and H\"{u}bl, Franziska and Majic, Ivan and Giannandrea, Daniele and Wastian, Matthias and Scholz, Johannes and Popper, Niki},
  title =	{{Calculating Shadows with U-Nets for Urban Environments}},
  booktitle =	{12th International Conference on Geographic Information Science (GIScience 2023)},
  pages =	{63:1--63:6},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-288-4},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{277},
  editor =	{Beecham, Roger and Long, Jed A. and Smith, Dianna and Zhao, Qunshan and Wise, Sarah},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.GIScience.2023.63},
  URN =		{urn:nbn:de:0030-drops-189581},
  doi =		{10.4230/LIPIcs.GIScience.2023.63},
  annote =	{Keywords: Neural Net, U-Net, Residual Net, Shadow Calculation}
}
Document
Short Paper
DOI: 10.4230/LIPIcs.GIScience.2023.82
Harnessing the Sunlight on Facades - an Approach for Determining Vertical Photovoltaic Potential (Short Paper)

Authors: Franz Welscher, Ivan Majic, Franziska Hübl, Rizwan Bulbul, and Johannes Scholz

Published in: LIPIcs, Volume 277, 12th International Conference on Geographic Information Science (GIScience 2023)

Abstract
The paper deals with the calculation of the photovoltaic potential of vertical structures. Photovoltaic systems are a core technology for producing renewable energy. As roughly 50% of the population on planet Earth lives in urban environments, the production of renewable energy in urban contexts is of particular interest. As several papers have elaborated on the photovoltaic potential of roofs, this paper focuses on vertical structures. Hence, we present a methodology to extract facades suitable for photovoltaic installation, calculate their southness and percentage of shaded areas. The approach is successfully tested, based on a dataset located in the city of Graz, Styria (Austria). The results show the wall structures of each building, the respective shadow depth, and their score based on a multi-criteria analysis that represents the suitability for the installation of a photovoltaic system.
Cite as

Franz Welscher, Ivan Majic, Franziska Hübl, Rizwan Bulbul, and Johannes Scholz. Harnessing the Sunlight on Facades - an Approach for Determining Vertical Photovoltaic Potential (Short Paper). In 12th International Conference on Geographic Information Science (GIScience 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 277, pp. 82:1-82:7, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{welscher_et_al:LIPIcs.GIScience.2023.82,
  author =	{Welscher, Franz and Majic, Ivan and H\"{u}bl, Franziska and Bulbul, Rizwan and Scholz, Johannes},
  title =	{{Harnessing the Sunlight on Facades - an Approach for Determining Vertical Photovoltaic Potential}},
  booktitle =	{12th International Conference on Geographic Information Science (GIScience 2023)},
  pages =	{82:1--82:7},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-288-4},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{277},
  editor =	{Beecham, Roger and Long, Jed A. and Smith, Dianna and Zhao, Qunshan and Wise, Sarah},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.GIScience.2023.82},
  URN =		{urn:nbn:de:0030-drops-189777},
  doi =		{10.4230/LIPIcs.GIScience.2023.82},
  annote =	{Keywords: Vertical Photovoltaics, Facades, Southness, Multi-Criteria-Analysis, Shadow}
}
Document
DOI: 10.4230/LIPIcs.STACS.2020.43
Identifiability of Graphs with Small Color Classes by the Weisfeiler-Leman Algorithm

Authors: Frank Fuhlbrück, Johannes Köbler, and Oleg Verbitsky

Published in: LIPIcs, Volume 154, 37th International Symposium on Theoretical Aspects of Computer Science (STACS 2020)

Abstract
It is well known that the isomorphism problem for vertex-colored graphs with color multiplicity at most 3 is solvable by the classical 2-dimensional Weisfeiler-Leman algorithm (2-WL). On the other hand, the prominent Cai-Fürer-Immerman construction shows that even the multidimensional version of the algorithm does not suffice for graphs with color multiplicity 4. We give an efficient decision procedure that, given a graph G of color multiplicity 4, recognizes whether or not G is identifiable by 2-WL, that is, whether or not 2-WL distinguishes G from any non-isomorphic graph. In fact, we solve the more general problem of recognizing whether or not a given coherent configuration of maximum fiber size 4 is separable. This extends our recognition algorithm to directed graphs of color multiplicity 4 with colored edges. Our decision procedure is based on an explicit description of the class of graphs with color multiplicity 4 that are not identifiable by 2-WL. The Cai-Fürer-Immerman graphs of color multiplicity 4 distinctly appear here as a natural subclass, which demonstrates that the Cai-Fürer-Immerman construction is not ad hoc. Our classification reveals also other types of graphs that are hard for 2-WL. One of them arises from patterns known as (n₃)-configurations in incidence geometry.
Cite as

Frank Fuhlbrück, Johannes Köbler, and Oleg Verbitsky. Identifiability of Graphs with Small Color Classes by the Weisfeiler-Leman Algorithm. In 37th International Symposium on Theoretical Aspects of Computer Science (STACS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 154, pp. 43:1-43:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{fuhlbruck_et_al:LIPIcs.STACS.2020.43,
  author =	{Fuhlbr\"{u}ck, Frank and K\"{o}bler, Johannes and Verbitsky, Oleg},
  title =	{{Identifiability of Graphs with Small Color Classes by the Weisfeiler-Leman Algorithm}},
  booktitle =	{37th International Symposium on Theoretical Aspects of Computer Science (STACS 2020)},
  pages =	{43:1--43:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-140-5},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{154},
  editor =	{Paul, Christophe and Bl\"{a}ser, Markus},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2020.43},
  URN =		{urn:nbn:de:0030-drops-119046},
  doi =		{10.4230/LIPIcs.STACS.2020.43},
  annote =	{Keywords: Graph Isomorphism, Weisfeiler-Leman Algorithm, Cai-F\"{u}rer-Immerman Graphs, coherent Configurations}
}
Document
DOI: 10.4230/LIPIcs.ISAAC.2018.46
Coresets for Fuzzy K-Means with Applications

Authors: Johannes Blömer, Sascha Brauer, and Kathrin Bujna

Published in: LIPIcs, Volume 123, 29th International Symposium on Algorithms and Computation (ISAAC 2018)

Abstract
The fuzzy K-means problem is a popular generalization of the well-known K-means problem to soft clusterings. We present the first coresets for fuzzy K-means with size linear in the dimension, polynomial in the number of clusters, and poly-logarithmic in the number of points. We show that these coresets can be employed in the computation of a (1+epsilon)-approximation for fuzzy K-means, improving previously presented results. We further show that our coresets can be maintained in an insertion-only streaming setting, where data points arrive one-by-one.
Cite as

Johannes Blömer, Sascha Brauer, and Kathrin Bujna. Coresets for Fuzzy K-Means with Applications. In 29th International Symposium on Algorithms and Computation (ISAAC 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 123, pp. 46:1-46:12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

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@InProceedings{blomer_et_al:LIPIcs.ISAAC.2018.46,
  author =	{Bl\"{o}mer, Johannes and Brauer, Sascha and Bujna, Kathrin},
  title =	{{Coresets for Fuzzy K-Means with Applications}},
  booktitle =	{29th International Symposium on Algorithms and Computation (ISAAC 2018)},
  pages =	{46:1--46:12},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-094-1},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{123},
  editor =	{Hsu, Wen-Lian and Lee, Der-Tsai and Liao, Chung-Shou},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ISAAC.2018.46},
  URN =		{urn:nbn:de:0030-drops-99942},
  doi =		{10.4230/LIPIcs.ISAAC.2018.46},
  annote =	{Keywords: clustering, fuzzy k-means, coresets, approximation algorithms, streaming}
}
Document
DOI: 10.4230/DagSemProc.07381.1
07381 Abstracts Collection – Cryptography

Authors: Johannes Blömer, Dan Boneh, Ronald Cramer, and Ueli Maurer

Published in: Dagstuhl Seminar Proceedings, Volume 7381, Cryptography (2008)

Abstract
From 16.09.2007 to 21.09.2007 the Dagstuhl Seminar 07381 ``Cryptography'' was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available.
Cite as

Johannes Blömer, Dan Boneh, Ronald Cramer, and Ueli Maurer. 07381 Abstracts Collection – Cryptography. In Cryptography. Dagstuhl Seminar Proceedings, Volume 7381, pp. 1-19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)

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@InProceedings{blomer_et_al:DagSemProc.07381.1,
  author =	{Bl\"{o}mer, Johannes and Boneh, Dan and Cramer, Ronald and Maurer, Ueli},
  title =	{{07381 Abstracts Collection – Cryptography}},
  booktitle =	{Cryptography},
  pages =	{1--19},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2008},
  volume =	{7381},
  editor =	{Johannes Bl\"{o}mer and Dan Boneh and Ronald Cramer and Ueli Maurer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.07381.1},
  URN =		{urn:nbn:de:0030-drops-12935},
  doi =		{10.4230/DagSemProc.07381.1},
  annote =	{Keywords: Cryptography, information security, public-key cryptography, cryptographic protocols, security proofs}
}
Document
DOI: 10.4230/DagSemProc.07381.2
07381 Executive Summary - Cryptography

Authors: Johannes Blömer, Dan Boneh, Ronald Cramer, and Ueli Maurer

Published in: Dagstuhl Seminar Proceedings, Volume 7381, Cryptography (2008)

Abstract
The topics covered in the seminar spanned most areas of cryptography, in one way or another, both in terms of the types of schemes (public-key cryptography, symmetric cryptography, hash functions and other cryptographic functions, multi-party protocols, etc.) and in terms of the mathematical methods and techniques used (algebra, number theory, elliptic curves, probability theory, information theory, combinatorics, quantum theory, etc.). The range of applications addressed in the various talks was broad, ranging from secure communication, key management, authentication, digital signatures and payment systems to e-voting and Internet security. While the initial plan had been to focus more exclusively on public-key cryptography, it turned out that this sub-topic branches out into many other areas of cryptography and therefore the organizers decided to expand the scope, emphasizing quality rather than close adherence to public-key cryptography. This decision turned out to be a wise one. What was common to almost all the talks is that rigorous mathematical proofs for the security of the presented schemes were given. In fact, a central topic of many of the talks were proof methodologies for various contexts.
Cite as

Johannes Blömer, Dan Boneh, Ronald Cramer, and Ueli Maurer. 07381 Executive Summary - Cryptography. In Cryptography. Dagstuhl Seminar Proceedings, Volume 7381, pp. 1-2, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)

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@InProceedings{blomer_et_al:DagSemProc.07381.2,
  author =	{Bl\"{o}mer, Johannes and Boneh, Dan and Cramer, Ronald and Maurer, Ueli},
  title =	{{07381 Executive Summary - Cryptography}},
  booktitle =	{Cryptography},
  pages =	{1--2},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2008},
  volume =	{7381},
  editor =	{Johannes Bl\"{o}mer and Dan Boneh and Ronald Cramer and Ueli Maurer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.07381.2},
  URN =		{urn:nbn:de:0030-drops-12928},
  doi =		{10.4230/DagSemProc.07381.2},
  annote =	{Keywords: Cryptography, information security, public-key cryptography, cryptographic protocols, security proofs}
}
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