A Universal Point Set for 2-Outerplanar Graphs

A point set $S \subseteq \mathbb{R}^2$ is universal for a class $\cal G$ if every graph of ${\cal G}$ has a planar straight-line embedding on $S$. It is well-known that the integer grid is a quadratic-size universal point set for planar graphs, while the existence of a sub-quadratic universal point set for them is one of the most fascinating open problems in Graph Drawing. Motivated by the fact that outerplanarity is a key property for the existence of small universal point sets, we study 2-outerplanar graphs and provide for them a universal point set of size $O(n \log n)$.Comment: 23 pages, 11 figures, conference version at GD 201

3D Shape Reconstruction from Sketches via Multi-view Convolutional Networks

We propose a method for reconstructing 3D shapes from 2D sketches in the form of line drawings. Our method takes as input a single sketch, or multiple sketches, and outputs a dense point cloud representing a 3D reconstruction of the input sketch(es). The point cloud is then converted into a polygon mesh. At the heart of our method lies a deep, encoder-decoder network. The encoder converts the sketch into a compact representation encoding shape information. The decoder converts this representation into depth and normal maps capturing the underlying surface from several output viewpoints. The multi-view maps are then consolidated into a 3D point cloud by solving an optimization problem that fuses depth and normals across all viewpoints. Based on our experiments, compared to other methods, such as volumetric networks, our architecture offers several advantages, including more faithful reconstruction, higher output surface resolution, better preservation of topology and shape structure.Comment: 3DV 2017 (oral

Drawing with SAT: four methods and A tool for producing railway infrastructure schematics

Schematic drawings showing railway tracks and equipment are commonly used to visualize railway operations and to communicate system specifications and construction blueprints. Recent advances in on-line collaboration and modeling tools have raised the expectations for quickly making changes to models, resulting in frequent changes to layouts, text, and/or symbols in schematic drawings. Automating the creation of high-quality schematic views from geographical and topological models can help engineers produce and update drawings efficiently. This paper introduces four methods for automatically producing schematic railway drawings with increasing level of quality and control over the result. The final method, implemented in the open-source tool that we have developed, can use any combination of the following optimization criteria, which can have different priorities in different use cases: width and height of the drawing, the diagonal line lengths, and the number of bends. We show how to encode schematic railway drawings as an optimization problem over Boolean and numerical domains, using combinations of unary number encoding, lazy difference constraints, and numerical optimization into an incremental SAT formulation. We compare drawings resulting from each of the four methods, applied to models of real-world engineering projects and existing railway infrastructure. We also show how to add symbols and labels to the track plan, which is important for the usefulness of the final outputs. Since the proposed tool is customizable and efficiently produces high-quality drawings from railML 2.x models, it can be used (as it is or extended) both as an integrated module in an industrial design tool like RailCOMPLETE, or by researchers for visualization purposes.publishedVersio

Algorithms for visualization of graph-based structures

Buildings today are built to maintain a healthy indoor environment and an efficient energy usage which is probably why damages caused by dampness has increased since the 1960’s. A study between year 2008 and 2010 showed that 26 percent of the 110 000 examined houses had damages and flaws caused by dampness that could prove to be harmful later on. This means that one out of four bathrooms risk the chance to develop damages by dampness. Approximately 2 percent of the houses had already developed water damages. It is here where the problems appear. A house or a building that is damaged by water of dampness need time to dry out before any renovation can take place. This means that damaged parts must be removed and allowed to dry out, this takes a long time to do and the costs are high and at the same time it can cause inconvenience to the residents. Here is where the Air Gap Method enters the picture. The meaning with the method is to drain and dry out the moisture without the need to perform a larger renovation. The Air Gap Method is a so called "forgiving"-system that is if water damages occur the consequences will be small. The Air Gap method means that an air gap is created in the walls, ceiling and the floor where a heating cable in the gap heats up the air and creates an air movement. The point is to create a stack effect in the gap that with the help of the air movement transports the damp air through an opening by the ceiling. The aim of this thesis is to examine if it’s necessary with the heating cable in the air gap and if there is a specific drying out pattern of the water damaged bathroom floor. The possibility of mould growth will also be examined. The study showed that the damped floor did dry out even without a heating cable, but as one of the studies showed signs of mould growth it is shown that the risk for mould growth is higher without a heating cable. There was a seven days difference in the drying out time between the studies with and without the heating cable; this difference can be decisive for mould growth which is why the heating cable is recommended. The Air Gap method is quite easy to apply in houses with light frame constructions simply by using a smaller dimension on the studs to create the air gap in the floor and walls. The method can also be applied in apartment buildings with a concrete frame by using the room-in- room principal. When renovating existing bathrooms it’s easier to use prefabricated elements to create the air gap in the floor and walls. ~

An interaction paradigm for impact analysis

The Aerospace industry is concerned with huge software projects. Software development is an evolving process resulting in larger and larger software systems. As systems grow in size, they become more complex and hence harder to maintain. Thus it appears that the maintenance of software systems is the most expensive part of the software life-cycle, often consuming 50-90% of a project total budget. Yet while there has been much research carried out on the problems of program and system development very little work has been done on the problem of maintaining developed programs. Thus it will be essential to improve the software maintenance process and the environment for maintenance. Historically, the term Software Maintenance has been applied to the process of modifying a software program after it has been delivered and during its life time. The high cost of software during its life cycle can be attributed largely to software maintenance activities, and a major part of these activities is to deal with the modifications of the software. These modifications may involve changes at any level of abstraction of a software system (i.e design, specification, code,...). Software Maintenance has to deal with modifications which can have severe Ripple Effects at other points in the software system. Impact Analysis addresses the problem and attempts to localize these Ripple Effects. In this thesis the Software Maintenance process and more specifically the Impact Analysis process is examined. The different parts of the implementation for the Impact Analysis System are explained. The main results of the thesis are the dependencies generation and the graph tool used to visualize these dependencies as well as the impacts on general dependency graph for impact analysis purpose

Planar Open Rectangle-of-Influence Drawings

A straight line drawing of a graph is an open weak rectangle-of-influence (RI) drawing, if there is no vertex in the relative interior of the axis parallel rectangle induced by the end points of each edge. Despite recent interest of the graph drawing community in rectangle-of-influence drawings, no algorithm is known to test whether a graph has a planar open weak RI-drawing, not even for inner triangulated graphs. In this thesis, we have two major contributions. First we study open weak RI-drawings of plane graphs that must have a non-aligned frame, i.e., the graph obtained from removing the interior of every filled triangle is drawn such that no two vertices have the same coordinate. We introduce a new way to assign labels to angles, i.e., instances of vertices on faces. Using this labeling, we provide necessary and sufficient conditions characterizing those plane graphs that have open weak RI-drawings with non-aligned frame. We also give a polynomial algorithm to construct such a drawing if one exists. Our second major result is a negative result: deciding if a planar graph (i.e., one where we can choose the planar embedding) has an open weak RI-drawing is NP-complete. NP-completeness holds even for open weak RI-drawings with non-aligned frames

A combinatorial approach to orthogonal placement problems

liegt nicht vor!Wir betrachten zwei Familien von NP-schwierigen orthogonalen Platzierungsproblemen aus dem Bereich der Informationsvisualisierung von einem theoretischen und praktischen Standpunkt aus. Diese Arbeit enthält ein gemeinsames kombinatorisches Gerüst für Kompaktierungsprobleme aus dem Bereich des orthogonalen Graphenzeichnens und Beschriftungsprobleme von Punktmengen aus dem Gebiet der Computer-Kartografie. Bei den Kompaktierungsproblemen geht es darum, eine gegebene dimensionslose Beschreibung der orthogonalen Form eines Graphen in eine orthogonale Gitterzeichnung mit kurzen Kanten und geringem Flächenverbrauch zu transformieren. Die Beschriftungsprobleme haben zur Aufgabe, eine gegebene Menge von rechteckigen Labels so zu platzieren, dass eine lesbare Karte entsteht. In einer klassischen Anwendung repräsentieren die Punkte beispielsweise Städte einer Landkarte, und die Labels enthalten die Namen der Städte. Wir präsentieren neue kombinatorische Formulierungen für diese Probleme und verwenden dabei eine pfad- und kreisbasierte graphentheoretische Eigenschaft in einem zugehörigen problemspezifschen Paar von Constraint-Graphen. Die Umformulierung ermöglicht es uns, exakte Algorithmen für die Originalprobleme zu entwickeln. Umfassende experimentelle Studien mit Benchmark-Instanzen aus der Praxis zeigen, dass unsere Algorithmen, die auf linearer Programmierung beruhen, in der Lage sind, große Instanzen der Platzierungsprobleme beweisbar optimal und in kurzer Rechenzeit zu lösen. Ferner kombinieren wir die Formulierungen für Kompaktierungs- und Beschriftungsprobleme und präsentieren einen exakten algorithmischen Ansatz für ein Graphbeschriftungsproblem. Oftmals sind unsere neuen Algorithmen die ersten exakten Algorithmen für die jeweilige Problemvariante

A combinatorial approach to orthogonal placement problems

liegt nicht vor!Wir betrachten zwei Familien von NP-schwierigen orthogonalen Platzierungsproblemen aus dem Bereich der Informationsvisualisierung von einem theoretischen und praktischen Standpunkt aus. Diese Arbeit enthält ein gemeinsames kombinatorisches Gerüst für Kompaktierungsprobleme aus dem Bereich des orthogonalen Graphenzeichnens und Beschriftungsprobleme von Punktmengen aus dem Gebiet der Computer-Kartografie. Bei den Kompaktierungsproblemen geht es darum, eine gegebene dimensionslose Beschreibung der orthogonalen Form eines Graphen in eine orthogonale Gitterzeichnung mit kurzen Kanten und geringem Flächenverbrauch zu transformieren. Die Beschriftungsprobleme haben zur Aufgabe, eine gegebene Menge von rechteckigen Labels so zu platzieren, dass eine lesbare Karte entsteht. In einer klassischen Anwendung repräsentieren die Punkte beispielsweise Städte einer Landkarte, und die Labels enthalten die Namen der Städte. Wir präsentieren neue kombinatorische Formulierungen für diese Probleme und verwenden dabei eine pfad- und kreisbasierte graphentheoretische Eigenschaft in einem zugehörigen problemspezifschen Paar von Constraint-Graphen. Die Umformulierung ermöglicht es uns, exakte Algorithmen für die Originalprobleme zu entwickeln. Umfassende experimentelle Studien mit Benchmark-Instanzen aus der Praxis zeigen, dass unsere Algorithmen, die auf linearer Programmierung beruhen, in der Lage sind, große Instanzen der Platzierungsprobleme beweisbar optimal und in kurzer Rechenzeit zu lösen. Ferner kombinieren wir die Formulierungen für Kompaktierungs- und Beschriftungsprobleme und präsentieren einen exakten algorithmischen Ansatz für ein Graphbeschriftungsproblem. Oftmals sind unsere neuen Algorithmen die ersten exakten Algorithmen für die jeweilige Problemvariante