Results 1 - 10 of 28

Tag-Cloud Drawing: Algorithms for Cloud Visualization

by Owen Kaser, Daniel Lemire , 2007
"... Tag clouds provide an aggregate of tag-usage statistics. They are typically sent as in-line HTML to browsers. However, display mechanisms suited for ordinary text are not ideal for tags, because font sizes may vary widely on a line. As well, the typical layout does not account for relationships that ..."
Abstract - Cited by 77 (2 self) - Add to MetaCart
Tag clouds provide an aggregate of tag-usage statistics. They are typically sent as in-line HTML to browsers. However, display mechanisms suited for ordinary text are not ideal for tags, because font sizes may vary widely on a line. As well, the typical layout does not account for relationships that may be known between tags. This paper presents models and algorithms to improve the display of tag clouds that consist of in-line HTML, as well as algorithms that use nested tables to achieve a more general 2-dimensional layout in which tag relationships are considered. The first algorithms leverage prior work in typesetting and rectangle packing, whereas the second group of algorithms leverage prior work in Electronic Design Automation. Experiments show our algorithms can be efficiently implemented and perform well.
(Show Context)

Using Curves to Enhance Parallel Coordinate Visualisations

by Martin Graham And, Martin Graham, Jessie Kennedy
"... This paper introduces a number of refinements to the Parallel Coordinates visualisation metaphor for multidimensional data. Firstly, the traditional set of poly-lines are replaced with a collection of smooth curves across the attribute axes, allowing individual data elements to be traced under certa ..."
Abstract - Cited by 22 (0 self) - Add to MetaCart
This paper introduces a number of refinements to the Parallel Coordinates visualisation metaphor for multidimensional data. Firstly, the traditional set of poly-lines are replaced with a collection of smooth curves across the attribute axes, allowing individual data elements to be traced under certain limitations; normally impossible due to the `crossing problem'. Then the notion of spreading out points on axes with a few discrete values is introduced, which leads onto a simple focus+context technique when the user selects values on such axes.

How important is the ”mental map”? — An empirical investigation of a dynamic graph layout algorithm

by Helen C. Purchase, Eve Hoggan - Graph Drawing, volume 4372 of Lecture Notes in Computer Science , 2006
"... Abstract. While some research has been performed on the human un-derstanding of static graph layout algorithms, dynamic graph layout al-gorithms have only recently been developed sufficiently to enable similar investigations. This paper presents the first empirical analysis of a dy-namic graph layou ..."
Abstract - Cited by 20 (0 self) - Add to MetaCart
Abstract. While some research has been performed on the human un-derstanding of static graph layout algorithms, dynamic graph layout al-gorithms have only recently been developed sufficiently to enable similar investigations. This paper presents the first empirical analysis of a dy-namic graph layout algorithm, focusing on the assumption that maintain-ing the “mental map ” between time-slices assists with the comprehension of the evolving graph. The results confirm this assumption with respect to some categories of tasks. 1
(Show Context)

Notes on Large Angle Crossing Graphs

by Vida Dujmović, Joachim Gudmundsson, Pat Morin, Thomas Wolle , 2010
"... A graph G is an α angle crossing (αAC) graph if every pair of crossing edges in G intersect at an angle of at least α. The concept of right angle crossing (RAC) graphs (α = π/2) was recently introduced by Didimo et al. [6]. It was shown that any RAC graph with n vertices has at most 4n −10 edges and ..."
Abstract - Cited by 12 (0 self) - Add to MetaCart
A graph G is an α angle crossing (αAC) graph if every pair of crossing edges in G intersect at an angle of at least α. The concept of right angle crossing (RAC) graphs (α = π/2) was recently introduced by Didimo et al. [6]. It was shown that any RAC graph with n vertices has at most 4n −10 edges and that there are infinitely many values of n for which there exists a RAC graph with n vertices and 4n − 10 edges. In this paper, we give upper and lower bounds for the number of edges in αAC graphs for all 0 < α < π/2. 1
(Show Context)

The straight-line RAC drawing problem is NP-hard

by Evmorfia N. Argyriou, Michael A. Bekos, Antonios Symvonis , 2012
"... A RAC drawing of a graph is a polyline drawing in which every pair of crossing edges intersects at right angle. In this paper, we focus on straight-line RAC drawings and demonstrate an infinite class of graphs with unique RAC combinatorial embedding. We employ members of this class in order toshow t ..."
Abstract - Cited by 10 (4 self) - Add to MetaCart
A RAC drawing of a graph is a polyline drawing in which every pair of crossing edges intersects at right angle. In this paper, we focus on straight-line RAC drawings and demonstrate an infinite class of graphs with unique RAC combinatorial embedding. We employ members of this class in order toshow thatit is NP-hardtodecide whether agraph admits a straight-line RAC drawing.
(Show Context)

On the perspectives opened by right angle crossing drawings

by Patrizio Angelini , Luca Cittadini , Giuseppe Di Battista , Walter Didimo , Fabrizio Frati , Michael Kaufmann , Antonios Symvonis - In Proc. 17th Int. Symp. Graph Drawing (GD 2009), volume 5849 of LNCS , 2010
"... Abstract. Right Angle Crossing (RAC) drawings are polyline drawings where each crossing forms four right angles. RAC drawings have been introduced because cognitive experiments provided evidence that increasing the number of crossings does not decrease the readability of the drawing if the edges cr ..."
Abstract - Cited by 9 (4 self) - Add to MetaCart
Abstract. Right Angle Crossing (RAC) drawings are polyline drawings where each crossing forms four right angles. RAC drawings have been introduced because cognitive experiments provided evidence that increasing the number of crossings does not decrease the readability of the drawing if the edges cross at right angles. We investigate to what extent RAC drawings can help in overcoming the limitations of widely adopted planar graph drawing conventions, providing both positive and negative results. First, we prove that there exist acyclic planar digraphs not admitting any straight-line upward RAC drawing and that the corresponding decision problem is NP-hard. Also, we show digraphs whose straightline upward RAC drawings require exponential area. Second, we study if RAC drawings allow us to draw bounded-degree graphs with lower curve complexity than the one required by more constrained drawing conventions. We prove that every graph with vertex-degree at most 6 (at most 3) admits a RAC drawing with curve complexity 2 (resp. 1) and with quadratic area. Third, we consider a natural non-planar generalization of planar embedded graphs. Here we give bounds for curve complexity and area different from the ones known for planar embeddings.
(Show Context)

Minimizing crossings in hierarchical digraphs with a hybridized genetic algorithm

by Pascale Kuntz, Bruno Pinaud, Rémi Lehn - J. HEURISTICS , 2006
"... Producing clear and intelligible layouts of hierarchical digraphs knows a renewed interest in information visualization. Recent experimental results show that metaheuristics are well-adapted methods for this problem. In this paper, we develop a new Hybridized Genetic Algorithm for arc crossing min ..."
Abstract - Cited by 8 (2 self) - Add to MetaCart
Producing clear and intelligible layouts of hierarchical digraphs knows a renewed interest in information visualization. Recent experimental results show that metaheuristics are well-adapted methods for this problem. In this paper, we develop a new Hybridized Genetic Algorithm for arc crossing minimization. It follows the basic scheme of a GA with two major differences: problem-based crossovers adapted from ordering GAs are combined with a local search strategy based on averaging heuristics. Computational testing was performed on a set of 180 random hierarchical digraphs of standard sizes with various structures. Results show that the Hybridized Genetic Algorithm significantly outperforms Tabu Search-which is one of the best known methods for this problem- and also a multi-start descent except for highly connected graphs.

CFB: a call for benchmarks - for software visualization

by Jonathan I. Maletic, Andrian Marcus - In 2nd IEEE Workshop of Visualizing Software for Understanding and Analysis
"... The paper argues for the need of a benchmark, or suite of benchmarks, to exercise and evaluate software visualization methods, tools, and research. The intent of the benchmark(s) must be to further and motivate research in the field of using visualization methods to support understanding and analysi ..."
Abstract - Cited by 6 (0 self) - Add to MetaCart
The paper argues for the need of a benchmark, or suite of benchmarks, to exercise and evaluate software visualization methods, tools, and research. The intent of the benchmark(s) must be to further and motivate research in the field of using visualization methods to support understanding and analysis of real world and/or large scale software systems undergoing development or evolution. The paper points to other software engineering sub-fields that have recently benefited from benchmarks and explains how these examples can assist in the development of a benchmark for software visualization. 1
(Show Context)

Elements for the description of fitness landscapes associated with local operators for layered drawings of directed graphs

by Pascale Kuntz, Bruno Pinaud, Rémi Lehn - METAHEURISTICS: COMPUTER DECISION-MAKING , 2004
"... ..."
Abstract - Cited by 4 (4 self) - Add to MetaCart
Abstract not found

Maximizing the total resolution of graphs

by E. N. Argyriou, M. A. Bekos, A. Symvonis - Proc. of 18th International Symposium on Graph Drawing (GD 2010) LNCS , 2011
"... A major factor aecting the readability of a graph drawing is its resolution. In the graph drawing literature, the resolution of a drawing is either measured based on the angles formed by consecutive edges incident to a common vertex (angular resolution) or by the angles formed at edge crossings (cro ..."
Abstract - Cited by 4 (1 self) - Add to MetaCart
A major factor aecting the readability of a graph drawing is its resolution. In the graph drawing literature, the resolution of a drawing is either measured based on the angles formed by consecutive edges incident to a common vertex (angular resolution) or by the angles formed at edge crossings (crossing resolution). In this paper, we introduce the notion of total resolution, that is, the minimum of the angular and crossing resolution. To the best of our knowledge, this is the rst time where the problem of maximizing the total resolution of a graph over all its drawings is studied. The main contribution of the paper consists of drawings of asymptotically optimal total resolution for complete graphs (circular drawings) and for complete bipartite graphs (2-layered drawings). In addition, we present and experimentally evaluate a force-directed based algorithm that constructs drawings of large total resolution.
(Show Context)