Visual content analysis applied to data and knowledge has been the main theme of the Information Visualization Conferences (iV) held since 1997 usually in London, UK. This article refers mainly to the selected papers presented in the Proceedings of iV08, the 12th International Conference on Information Visualisation*. Notes about the selected articles focus on presentational exploration, understanding of the language of visualization, along with the interactive context and culture of knowledge visualization. Projects, often conceived as cross disciplinary, comprise issues on information visualization, design visualization, knowledge domain visualization, cultural heritage knowledge visualization, web mining and open source intelligence, geo-analytics, semantic web, applications of graph theory, and visual analytics.
This article provides some notes about the visual content analysis
applied to data and knowledge in many domains. These notes refer mainly to the selected
articles presented in the Proceedings of iV08, the 12th International Conference on Information
Visualization held in London, UK*. Beyond visualization and presentational
exploration, the contributors focus on understanding of the language of
visualization, along with the interactive context and culture of knowledge
visualization. The theme for the 2008 12th International Conference Information Visualizationis "Shifting Focus to Content
Analysis and Widening Applications." Projects, often conceived as cross
disciplinary, comprise information visualization, design visualization, knowledge
visualization, cultural heritage knowledge
visualization, web mining
and open source intelligence, semantic web, applications of graph theory, and visual
analytics*. The
Symposium and Gallery of Digital Art (D-Art) accompanies the Conference. Art
works and short videos from the D-Art 2008 Gallery, along with figures taken
from the Conference papers, illustrate this article.
Figure 1. Jing Zhou, Infinity. Digital mixed media on paper
Information
visualization
Information visualization
is sometimes defined as representation + interaction, but interaction is often
given only secondary attention (Ji Soo Yi, Youn ah Kang, Stasko, & Jacko, 2007*). Several models of information
management address the data presentation, mapping, and temporal dimension issues.
According to Cottam
and Lumsdaine* (2008, pp. 51-56), the existing
information visualization models are insufficient for visualization programmers
in creating applications, especially where interaction is concerned. They are either
too broad and taxonomy based (which is good for categorizing what has been or
needs to be done, but provide little help in accomplishing those goals), or
narrowly focused on isolated aspects of the visualization problem (which allow
particular aspects of the visualization problem to be efficiently solved, but
leave heavy burdens for integrating many such narrow tools together to solve
the overarching visualization problem).The authors describe the Stencil
visualization model that can guide visualization program construction through
several stages of common application pipelines. They employ a declarative Domain-Specific
Language called the Stencil Language, thereby overcoming the interaction
shortcomings, improving the resulting visualization products, and reducing
significant barriers to visualization adoption.
Figure
2. Joohyun
Pyune. 0002. Dye sublimation printed on fabrics
Craft and Cairns* (2008, p. 44-50) overviewed methodologies
in Information Visualization design and methods for designing novel
visualizations. According to the authors, current knowledge comes in the form
of:
Design examples that
provide solutions
Taxonomies that
categorize and list artifacts
Guidelines that
recommend best practices and
Reference models that
describe how visualization systems work as a whole.
For example, the visualization
reference model proposed by Card, Mackinlay, & Shneiderman (1999) describes
activities necessary to create visualization systems that include transforming
raw data into structured data, as data tables, and then further data transformations
allowing for calculations of meta-data attributes. Visual mapping of attributes
allows mapping the structures essential to the data into the abstract visual
structures that can be interactively transformed on a screen by the users as
changes in shape, color, size, location, etc.
Figure 3. Monika Wulfers. Blue print, Disturbance 12. Digital Print on Hahnemuehle Photo Rag
A novel visualization approach
to support understanding microarray data has been implemented in close
collaboration with neurobiologists, to analyze and understand data about activity
of genes (called as gene expression or gene regulation) and, going one step
further, make a switch to combinations of genes (Tominski and Schumann*, 2008, pp. 120-126). Gene combinations bear
more information, and hence can lead to new hypotheses about the data. More and
more biological experiments are conducted based on microarray technology. The
authors present the approach that allows biologists to interactively explore
and to visually compare different combinations of genes. They developed an
analysis pipeline, for filtering of genes for data analysis, generating gene
combinations, then filtering of gene combinations and visualizing several
hundreds of gene combinations as multiple panels floating (in a way of small
multiples) in 3D. The implementation of the visualization of gene combinations
(ViGeCo) is available as a plug-in for the microarray data analysis framework
Mayday.
Figure 4. Daniel Durning. 100 Drawings No.1. Chromo Graphic Print on Rag Paper. The
phenomenal transformation from the simple line to an iconic ideal. This
composition was rendered as a final animation.
Another project accomplished in
close collaboration with biologists focused on a comparison of metabolic
networks (Bourqui and Jourdan*, 2008, pp. 638-643).
Large-scale networks such as gene networks, protein–protein interaction
networks, or metabolic networks, comprise sets of interconnected reactions that
can be modeled as small graphs called metabolic pathways. Networks, often
containing hundreds of elements, many times share some biologic functions.
Visual mining tool allows mining the newly discovered metabolic networks and
comparing them to already known ones. Such comparison could be done using
pathways (clusters). The authors helped biologists in their understanding of
the different metabolic properties of bacterial organisms belonging to a major
group (phylum) of bacteria. By defining color-coded drawing algorithms and
navigation methods they visualized the networks and their hierarchies. The network
classification hierarchy allowed comparative analysis. Navigation went through
levels: the highest level – hierarchy, intermediate level –
metabolic network, and the lowest level – metabolic pathway. Thus the
authors took advantage of network clustering when comparing networks.
Gaudin and Quigley* (2008, pp. 227-232,
Fig. 5a, 5b) present interactive structural
clustering of graphs based on node-link and matrix multi-representations. Representations of
graphs with hundreds of nodes are hardly readable.
Gaudin and Quigley, node-link graphs.
Figure 5a. A graph with 998 nodes
represents a part of the MySpace social network.
Figure 5b. Applying structural clustering
helps make the graph more readable
In this example,
nodes represent MySpace accounts (or people who have those accounts) and each
edge between two nodes represents a link between two accounts. Multi-representation
of a same graph is applied, in order to interactively cluster it, so the user
iteratively employs a clustering technique and visualizes the result. One node of the
clustered graph represents a set of nodes of the initial graph. Applying interactive
structural clustering of graphs brings the number of nodes down and thus makes
these graphs more readable (Gaudin and Quigley, pp. 227-232).
Figure 6. The LED display ceiling art (Tomitsch et al. p.101) in a Beijing shopping mall (left) and the
multimedia sky above the winter garden of the Bertelsmann residence in Berlin
(right).
The ceiling may serve as a
physical surface for information visualization. Tomitsch, Grechenig, Vande
Moere, & Renan* (2008, pp. 100-105) present a
notion of 'information sky' based on:
(1) The metaphor of the natural
sky,
(2) Historical
examples of ceiling art (such as paintings in Altamira cave or Medieval and
Renaissance frescos), and
(3) Recent computing paradigms.
Particular
models employed in computing include Mediatecture
(such as large-screen displays in public spaces fo display of visualizations
of data, weather, or stock data, for example), Ubiquitous
computing technology (user-driven applications allowing interaction over a
distance), and Ambient
display acting at the periphery of human attention.
The authors define three
categories for the information sky. Contextual information, based on the
concept of ambient display, provides awareness of information such as weather
conditions. Navigation and guidance within architectural environment using
navigational cues on the ceiling provides a sense of orientation and directions
toward exits. Storytelling – short dialogues inform people about
historical events or conversations that happened in that space.
Videos. Sphere: two visualizations by Petersen, Canig.
Interactive
information visualization applications in terms of graphics performance and
interactivity have not yet been investigated in a context of browser-based
application platforms. Web browser based applications have become very popular
in many domains, and the interactive information visualization developers must
choose the browser-based applications knowledgeably. Lammarsch, Aigner,
Bertone, Miksch, Turic, & Gärtner*
(2008, pp. 194-199) assess browser-based programming platforms by comparing
server-based rendering, Java applets, Flash, and Silverlight in terms of their
run capability, rendering graphics primitives, user-controlled animation, user
interaction, communication with a server, stability, and experience. The
authors consider server-based rendering, Flash and Java as safe bets.
Applications for mobile devices such as handhelds and smart phones make
easy to use them as desktop applications. Usage of information visualization
techniques reduces limitation caused by a small visual area for analysis, and
enhances the presentation, search, and analysis of data. Clayton et al.* (2008, pp. 264-269)
present a data analysis tool for mobile devices that is characterized by
portability, scalability and code reuse. Coordinated views enhance the user's
perception over data and diminish difficulties caused by a small display size.
The authors’ visualization techniques include the scatterplot graph with the
data geo-referenced in the maps, and the treemap visualization of hierarchical
structures.
Figure 7. Gabriele Peters. Dark Days -
Prague: isolation of the modern human being
Design Visualization
As Andrew Vande
Moere* stated earlier (2005), “there is empirical evidence showing that
designers use information visualization as a creative concept for determining
the design outcome. Vice versa, interdisciplinary concepts, such as design
cognition, user engagement, aesthetics, and art, can enhance information
visualization. Current trend of information aesthetic visualization is focused
on employing visual and interactive aesthetics to represent data in pleasurable
and intelligible way. While discussing contemporary
methods that represent abstract information in a physical way, Vande Moere* (2008, pp. 469-474) introduces five
different degrees of ‘data physicality’, which differ in the level of
abstraction of how data is mapped and perceived by human senses: ambient
display, pixel sculptures, object augmentation, data sculptures, and alternative
modality. The author stresses the potential of information visualization as a
communication medium in its own right, which proliferates beyond the ubiquitous
pixel-based, light-emitting surfaces of today.
Figure 8.
Tim Portlock. Images created in a 3D modelling application after
abandoned buildings. A series of prints about the decline of urban space.
Non-photorealistic
rendering (NPR) is a relatively new field that focuses on viewer engagement by
the use of stylization, abstraction, and expressiveness (Gatzidis,
Papakonstantinou, Brujic-Okretic, & Baker*,
2008, pp. 475-480). Evaluation studies of such approaches support the developments
in NPR techniques. The most notable include psychological, architectural, and
medical applications, space perception in immersive environment, depiction with
the use of texture, learning applications, and visualizing natural phenomena.
New techniques in visualization
design that may aid comprehension in analysis of complex data include methods
such as mechanical, symbolic, and natural analogies (Brath, 2008, pp. 481-484).
Creating new visualizations may result from computational generation or designs
done by information designers with the use of analogy (mechanical, natural and
biologic, or iconic analogies) and metaphors. Challenges associated with
creating novel visualizations include metaphor entrapment and validation of the
implementation effectiveness.
Figure 9. Hans Dehlinger. Quadrat 60-60-2. Generative
line oriented pen-plotter pencil drawing.
Knowledge Domain Visualization
Remo Burkhard introduced “Knowledge Visualization” as the name for
a field that investigates the use of visual representations to transfer
knowledge between at least two people. Then he proposed, with Martin Eppler, a
systematic “Knowledge Visualization Framework.” They suggested applying the
understanding of the field as a problem solver, not only a meta-science. Agent-based
crowd simulation tools have been primarily used in architecture and urban
planning for analytical purposes, such as the simulation of pedestrians or fire
escape scenarios in buildings. Because of the high cost-benefit ratio, they
were only rarely used for communication purposes, for example for marketing
purposes. To bridge the fields of architecture and commercial crowd simulation,
Burkhard, Bischof, & Herzog* (2008, pp. 403-408)
discuss crowd simulations for analytical purposes and case studies done with
commercial software Massive. They consider this relevant for architects, urban
designers, communication and PR experts, and for researchers in the fields of
architecture, knowledge visualization, communication science, and agent-based
simulations.
Figure 10. Mark Stock. “p71-169” The emerging form of a blob of
fluid. Simulations of the self-interaction of an initially-spherical fluid
interface and tracked its evolution into ever-more complex forms.
Francis T. Marchese* (2008, pp. 75-81) explores early visualizations, for instance, the development of the chemical table, with a history of over 300 years,
as the textbook case of information visualization. The quality of the periodic
table of elements as an early visualization
achievement inspired Ralph Lengler and Martin J. Eppler*to create a periodic table of 100 visualization methods. Also,
Visual Literacy.org* published the
“Interactive Knowledge Maps of Tools, Books, Researchers, Success Factors, and
Methods in the Visualization Field.”
Figure 11. LiQuin Tan. Rusty Faces. Large-scale
printing on metal materials
In their article "Seven Types of Visual Ambiguity: On the
Merits and Risks of Multiple Interpretations of Collaborative Visualizations"
Eppler, Mengis, & Bresciani* (2008, pp. 391-396)
examined visual ambiguity. Visuals
catalyze collaboration. Ambiguity or the
openness to multiple interpretations typifies visualizations such as sketches,
diagrams, visual metaphors, etc., sometimes causing misunderstandings but often
offering the potential to reveal new insights, facilitate ad-hoc discoveries,
reframe issues, increase identification, or stimulate group sense making.
William Empson wrote, “'Ambiguity' itself can mean an indecision as to what you
mean, an intention to mean several things, a probability that one or other or
both of two things has been meant, and the fact that a statement has several
meanings” (Empson, 1932, 5, citation after Eppler et al., 2008, pp. 391-396). Thus,
an arrow can be used to represent a vector (with position, orientation, and
magnitude), a transition, a designator (i.e. pointing to an object), or a
casual or temporal relationship. Two simple examples of intended perceptual
(visual) ambiguity are: a picture of a duck that becomes a rabbit (Jastrow, J.,
1899, The Mind's Eye, Popular Science Monthly, Vol.54, pp. 299-312) and an old lady
that can also be seen as the profile of a young one (Boring, E. G., 1930, A New
Ambiguous Figure, American Journal of Psychology, Vol. 42, p. 444). Roland Barthes
performed semiotic analyses of the rhetoric of images that he considered
polysemic (with many messages).
Figure 12. John Antoine Labadie.
Biodendrite_groupXX. One of visualizations in the fields of chemistry,
mathematics, physics, and nanotechnology
The connotations of the image depend on the context of the image
and the characteristics of the viewer. Ambiguity allows for flexibility over
time, re-interpretations, and the coexistence of several perspectives. It can
become strategic (as a communication device) or perceived (unintentional).
Visual ambiguity in the group contexts is a relational variable that depends on
three elements (categories): the visual (properties of the image), the people
interpreting the image, and the interaction among the people through the visual
(according to Eisenberg, 1984, a combination of source, message, and receiver
factors). The authors discuss seven types of visual ambiguity under these three
categories: iconic, symbolic, and indexical ambiguity (belonging to the
property of the visual category), interpreter background and familiarity
(belonging to the property of the people), focus, and scope ambiguity (belonging
to the interaction category).
Figure 13. Helen S. Golden. IDEA of
Beach – A series of IDEAS.
Cultural Heritage Knowledge Visualization
Because the practice of
visualization of the digital cultural heritage is well-established, Flynn* (2008, pp. 447-452) stresses that digital
cultural heritage needs to reflect contemporary interpretative practices besides
the material data. Material culture has usually been presented as high quality
digital artifacts, their production drawn on the potential for augmented
visualization offered by mobile technologies, game engines, and responsive
environments. While leading research in interpretative heritage has
incorporated the hermeneutic aspects of previously lived cultures, there have
been less recognition of the importance of the users’ role in the formation of
cultural knowledge. The author investigates the processes of knowledge
formation and phenomenological research in archaeology in the light of theoretical
readings on perception, and points to the need to devise alternative methods
for the design and production of an interpretative digital cultural heritage.
Such methods detail the generative potential of a complex process rather than
the replication of a complex structure.
Phenomenological archeologists
put emphasis on movement and spatial practice, with motion, vision, and
comprehension being inseparable in the somatic space of a body. Also, the
phenomenological concept of landscape as a factor in knowledge formation
describes the creating and experiencing the perception of the environment through
the manner it is approached and sensed. The somatic method outlines the
encounter between the human body and prehistoric architectural space, by capturing
somatic impulses and affective responses made evident by performance. In a
similar way, Tilley, and then Girot
and Truniger (2006)stress that to
understand the specific situation of a walking perceiver,visualizations of landscapes must include dynamic
parameters from the vantage point of the pedestrian.
Figure 14. Luz del Carmen. Changes
Indigenous
knowledge visualization exemplifies the
ways in which different people organize data in diverse ways,
often involving conveying the meaning that is
dependent on the context in which it is used.Australian Aboriginal art can be seen as survival topographic maps
and also the cultural heritage survival maps with clear parallels in the
iconography of secret sacred motifs (Wyeld*,
2008, pp. 439-446, fig. 15a, b). Australian Aboriginal art, that denotes the means of which particular acts are performed, uses numerous media including tactile painting of petroglyphic forms
in sand (involving performative art with dance and songs) and acrylic painting on
board, often serving as the storytelling navigation aid.
Figure 15a. Ngarlu
Love Story, Clifford Possum, Tjapaltjarri (Acrylic on canvas).
A story of forbidden
love.
Figure 15b.
Annotation of Ngarlu Love Story.
Visualization of knowledge domain of Australian Aboriginal
people is achieved in contextualized nonlinear stories with the meaning
dependent on traditional landscapes and knowledge practices. The viewer’s
experience becomes both collaborative and performative, when the storyworld unfolds real-time narratives
involving Elders and the ancestral spirits of the landscape and supports
narratives about land ownership issues, spiritual knowledge, and historic and
oral stories (Pumpa & Wyeld, 2006). Cultural heritage survival maps shed new light on understandings
of the indexicality and aid to form a theory of the cultural specificity of the
conventions used and their role as storytelling navigation aids.
Figure 16. Daria Tsoupikova. “Passing
excellence.” Visualization of the world famous Kizhi site as an interactive 3D virtual environment.A 3D model of the 1764 Church
of the Intercession and the Belfry. The Kizhi
ensemble is
included in the List of Most Endangered Sites of the World Monuments Watch
protected by World Heritage List of UNESCO.
Architecture can be considered
a transition from an initial idea of architecture to its realization that
traces out the complexity of the process (Giordano et al.*,
2008, pp. 433-438). The authors propose the management, in a hypertext, of
drawings, surveys, maps and historical iconography, real and digital movies of
CAD reconstruction (taking, as a case study, the ecclesiastical architectural
heritage of the Padua historic centre. The authors recognize the importance of
knowledge of configurative geometry for creative thinking, scientific knowledge,
and practice. They also attribute to a geometric knowledge a founding role for displaying
knowledge of the cultural heritage. This knowledge allows processing manual and
digital graphics and constructing motion images. Moreover, flexible geometry
still ensures achieving a high level of expressive capacity aimed at both the
documentation and the design of complex spaces and structures. This instrument
for representation is not only a way of imitating reality but has an enormous
analytical/cognitive potential as a cognitive medium able to create possible
worlds.
A relational database of the cultural
heritage contained in ancient maps and charts, which are already preserved in
the main Spanish collections, archives, and libraries, has been designed and
implemented by Chias and Abad* (2008, 4pp. 53-457).
Initiation of this project is aimed to bridge the gap between the routine use
of texts and writings and the seldom-applied analysis of old cartographic documents showing
the historical evolution of the territories and landscapes. The database
provides the possibility to access to a high-resolution digital image of each ancient
cartography document or a map. The personalized queries to the database will
allow the scholars and searchers to visualize the document together with its
main features.
The Physical Review Dataset
created by Herr II, Duhon, Börner, Hardy, & Penumarthy*
(2008, pp. 421-426) is the first map of 113 years of bibliographic data from the
American Physical Society. The 389,899 documents are laid out in a two-dimensional
time-topic reference system. The citations from 2005 papers are over laid as
flow maps. The authors rendered this visualization at a 24" x 30"
canvas at 300 dots per inch (DPI).
Figure 17. Corinne Whitaker. Squircle 46. Digital 2D painting.
Kimono is a key point in
Japanese culture. Ching-jung Lin and Jhong-Jyun Guo*
(2008, pp. 458-461) accomplished a study of kimono design aimed at the kimono
pattern culture conservation. The authors collected different kimono patterns
to analyze and induce their shape grammar and then build a design system of
kimono pattern based on this grammar. This system provides information
concerning visualized patterns such as pattern elements (color, alignment, and
etc.), enabling the customers to choose the style they prefer, so they get
involved in the design process. The pattern elements generated by the
customer’s likes are incorporated into the kimono pattern grammar that is
constructed and refined on the basis of the results of this design system. The
refined grammar can be used to analyze the existing kimono patterns. Through
the continuing refinement and analysis of the kimono grammar, the authors traced
back the history of a kimono by its pattern, and, through generative design, made
it possible to preserve the cultural assets – the kimono pattern, its
design knowledge, and Japanese cultural heritage.
Video. Animation by Brian Leister.
Photographs of art works and
photographs by themselves are used in inventories describing Italy’s artistic
heritage (Pigozzi*, 2008, pp. 462-465). In spite
of some political discourses, academic constraints, and cross-disciplinary
inflexibility, photographs have now come to be considered part of our cultural
heritage. With possible quality and faithfulness of an image, photographic
reproductions augment the cultural heritage and should not be confused with
plagiarism. The author poses a need to create interactive network offering
users online access to cultural resources and shared heritage through the
digitalization of art collections belonging to archives, libraries, and
museums. This task requests digitizing and archiving photographs, and then
interactive cataloguing based on coherent descriptive strategies.
Figure 18. Gloria DeFillips Brush. Reconstituting. Layered and
unflattened digital master files show an opened book as the recurring
connotative premise and arena for interactions of language, objects, and
pictures.
Web Mining and Open Source Intelligence
Open source information comes from publicly available sources that
are not covert or classified. Open source intelligence is a discipline that
refers to finding, selecting, and analyzing information from publicly available
sources.
Advances in
information technology made open sources more accessible, but the raw data is
heterogeneous for type (web pages, claims, crime reports), source (Internet, Intranet
- a private computer network accessible only to authorized persons, database,
etc.), protocol (HTTP - Hypertext Transfer Protocol, HTTPS - Hypertext
Transfer Protocol over Secure Socket Layer, FTP - File Transfer Protocol, GOPHER - a distributed document search and retrieval network
protocol, IRC - Internet
Relay Chat, NNTP - Internet Relay Chat, etc.) and language used. Information retrieval is limited by insufficient
keywords and diverse linguistic and cultural backgrounds. Neri and Pettoni* (2008, pp. 314-320) describe a Stalker, a
Multilingual Text Mining platform for open source intelligence that provides
deep semantic search and enables analysis of great volumes of heterogeneous
documents.
Figure 19. Philip Saunders. Lumen
Triptych. Digital photography, image
processing, painting, and compositing, to create images of the movement of
light through dark, as an observer travels through time and space.
Identifying social communities is a growing research area in the
open source intelligence and Web mining domain. Researchers concentrate on
customer relationships, or on identifying terrorist groups. Information can be
derived from the Call Detail Record (CDR) data from telecommunication
companies. Data include customers' calling destination numbers, duration and
frequency for each number for a given period of time. Kianmehr and Alhajj* (2008, pp. 308-313) discuss application of cluster analysis to identify
calling patterns in communities.
Mega-collaboration of great numbers of people, supported by
information and communication technology, needs a tool that would let coordinate and link activities of sub-teams, enable teammates to
visualize each other's mental models, and give the means to visualize
efficiently the "big picture" by individual teams. Each sub-team can
develop its own model of its part of the task, with the aid of web-based
software agents. Agents support back-end processes, while human-computer
interaction (HCI) visualization techniques must support the front-end process.
Newlon, Faiola, and MacDorman* (2008, pp. 509-514)
report the progress in designing and testing a prototype of mega-collaboration
interface. The second-generation interface is being implemented, and a novel
agent-based interface is being planned.
Figure 20. Laurence Gartel. RETROLG. Early digital work.
GeoAnalytics
Geovisual analytics
focuses on finding location-related patterns and relationship. Jern et al.* (2008, pp. 200-207) developed a method,
based on the Visual Analytics (VA) toolkit within the previously introduced
GeoAnalytics Visualization (GAV) framework, that supports the storage of
interactive events through snapshots - "memorized interactive visualization
views." An analyst can present and share gained insights over the Internetusing
interactive visualizations embedded in standard HTML documents. The authors
demonstrate interactive performance of demanding visualizations in the context
of GeoAnalytics and molecular visualization scenarios. Further enhancements (Jern,
Rogstadius, Åström, & Ynnerman*, 2008,
pp. 362-372) facilitate scaling geovisual analytics of large spatial geospatial
data. These are: 1) texture-based geographic mapping that exploits GPU-based
rendering performance applied to overview + detail views, 2) statistical
methods embedded in parallel coordinates, 3) aggregated dynamic grid maps.
Large-scale virtual city 3D
models transport huge amounts of different information, such as facade textures,
aerial photographs, infrastructure models, and city furniture, thus creating
information overload. The interactive focus + context visualization (Trapp,
Glander, Buchholz, & Döllner*, 2008, pp.
356-361) facilitates the exploration of complex information spaces. This is
possible due to the use of the 3D generalization lenses that direct users
attention to the detailed focus region, while showing the generalized context
information.
Color-coding is widely used for
scalar data that hold only one value at a time. To generate expressive and effective visual representations, it
is extremely important to carefully design the mapping from data to color. To
create expressive and effective visual representations, color-coding strategies
are introduced (Tominski, Fuchs, & Schumann*,
2008, pp. 373-380), that adapt the color mapping function to support tasks like
comparison, localization, or identification of data values.
Shipping companies must
consider many parameters before making decisions concerning many ships, cargoes,
and routes. The Visualize Performance Data (VISPER) application (Lundblad,
Jern, and Forsell*, 2008, pp. 381-388) combines
InfoVis components with logistics visualization to facilitate decision-making,
by gathering insights about the multi-dimensional, multi-source, time-varying
and geospatial digital information from voyage analysis.
Figure 21. Bruce Wands. The
Buddha Light Painting. A series of abstract images based on the ancient sacred
geometry that dates back several thousand years and forms the basis for many
types of Buddhist art.
Semantic Web
The semantic web has been described by the W3C director Tim
Berners-Lee asan evolving
extension of the World Wide Web, where information is understandable by
computers, so they become capable of finding, sharing, combining, and analyzing
all the data on the Web (Semantic Web*,
2009). Web content comprises text documents (composed mostly of HTML), images
(mostly graphics), audio and video files, animations, and any conceivable
materials such as data, applications, Web pages, e-services, or archived e-mail messages. Semantic web
involves examining internal content of the relations in a network of concepts,
and uses words and symbols as labels for data. Thus, the semantic web comprises
philosophy, design principles, collaborative working groups, and technology (Semantic
Web, 2009).
Semantic
network represents semantic relations between the concepts and is often used to
represent knowledge. It is a directed or undirected graph that consists of
vertices representing concepts, and edges defining relations between the
concepts. Google estimates around 427k RDF
documents on the Web and other sources list even more, up to 27m documents (Kinsella, Bojars, Harth, Breslin, & Decker*,
2008, pp. 179-184). Scientists develop intuitive way of viewing current usage of RDF vocabularies. Kinsella et al. present a system
allowing a user to view the most frequently occurring namespaces and classes in
a large Semantic Web dataset, with the main linkage patterns that exist between
them. Semantic network technology enables constructing collective scholarly knowledge
and expertise from publicly available data. POLYPHONET – a social network
mining system (Oka and Matsuo*, 2008, pp. 349-355)
is used to extract relations of researchers, to detect groups of researchers,
and to obtain keywords for a researcher.
Figure 22. Ina Conradi.
Natural SystemsTen.
Ontology is a basic component of the Semantic Web, a document or file that
formally defines terms and relations among terms. Ontologies collect
information about objects, their classes, properties, relations, and changes in
properties and relations, and thus help the users
understand, exchange, analyze or share knowledge of a specific domain. Visualization
of the structure of ontologies helps users understand and manipulate very large and
complex ontologies. Visualization of instances related to ontology structure
represents the real world objects, for example, curricular structures and
instances are needed to represent individual college courses. Kriglstein and Motschnig-Pitrik* (2008, pp. 163-168) present Knoocks
(Knowledge Blocks), a visualization approach focused on instances related to
ontologies’ structure, and they compare it with Jambalaya and CropCircles.
Figure 23. Jacquelyn Ford Morie. Morie’s Memories Of. The work All My Avatars: Information Visualization
of my Self: how online and social worlds have opened up new modes of expressing
and visualising information about our Self.
Applications of Graph Theory
Graph drawing for
visualization finds a growing number of applications in various disciplines,
and many attempts aim to produce aesthetically
pleasing visualization of graphs, many times as force directed graphs with the
edges of the graph having equal length, and as few crossing as possible. Kumar,
Zhang, & Wang* (2008, pp. 38-43) developed
the E-Spring algorithm for visualizing clustered directed acyclic graphs (DAGs)
without node overlapping. In this visualization nodes are modeled as physical
bodies, the charged particles with weights, and edges are represented as
springs that provide forces between the bodies. With this approach, a final
drawing is derived by adjusting the positions of the nodes according to a
combination of spring forces and repulsive forces derived from electrostatic
forces between the nodes. The two basic problems of graph drawing –
drawing of nodes and drawing of edges – are often handled by one
algorithm, which finds suitable positions for both nodes and edges (Dokulil and Katreniakova*, 2008, pp. 626-631).
Figure 24. Lane Last. Universal Path. Computer-mediated Art.
Several
standards (formal specifications) accompany the usage of semantic web, for
example, the W3C based standards: Resource Description Framework RDF, Web
Ontology Language OWL, URI, or HTTP. The Resource
Description Framework (RDF)* is a web metadata language that describes
information about web resources and the semantic data in the Web. Its abstract syntax reflects graph-based data models and formal
semantics in the Web.
The RDF data can be presented
visually as an oriented, labeled graph, so it gives the user an idea about data
content and structure. However, there are millions of nodes and edges. To handle the data, users cannot display the whole data but
rather have to draw sub-graphs and navigate
the data. Dokulil and Katreniakova* (2008, pp. 26-31) designed and implemented a
visualizer – a user-friendly visual navigation technique, applying
animation with the use of the Trisolda semantic web infrastructure. Users make their navigation trees and mental maps in their minds.
As the RDF data format –
the basic format for the semantic web – is by its very nature a graph, the
authors (Dokulil and Katreniakova, 2008*,
pp. 191-193) created an RDF visualizer that allows some basic support to design a visual
query of the data based on directed labeled graphs. The authors (Dokulil and
Katreniakova, 2008, pp. 626-631) present also an algorithm for drawingthe edges in RDF visualization, which
draws only the edges, no matter what the positions of the nodes are. The
algorithm is needed when positions of nodes are fixed, for instance, defined by
the user or the exact position of the nodes is somehow significant.
Figure 25. Karin Kuhlmann. Big Thing. Created with Ultra Fractal 4.
Euler diagrams –
collections of labeled closed curves – represent information about between
sets and their relationships; they have numerous applications including:
visualizing biological data, diagrammatic logics, and visual database querying.
Until now Euler diagrams must be laid out by hand. Rodgers, Zhang, Stapleton,
& Fish* (2008, pp. 585-593) introduce software for a
novel automated layout of Euler diagrams, a method for embedding such diagram
from wellformed dual graphs (having no triple points, concurrent curves,
disconnected zones, or non-simple curves).
A wiki system is used for
semantic annotation, comments, discussions, versioning, notification, and
full-text search (Giereth & Ertl*, 2008, pp. 185-190).
A wiki is a page or collection of Web pages designed to enable anyone who
accesses it to contribute or modify content. Wikis are often used to create
collaborative or community websites. The collaborative encyclopedia Wikipedia
is one of best-known wikis (http://en.wikipedia.org/wiki/Wiki).
The authors, Giereth & Ertl (2008, p. 185-190) use
semantic wikis for data search and annotation, integrating interactive
visualizations into semantic wikis. A semantic
wiki has an underlying model of the knowledge described in its pages. Semantic wikis* allow the ability to capture or identify
further information about the pages' (metadata) and
their relations.
Supporting research in
historical archives. Historical archives take form of digital libraries
enhanced with the incorporation of semantics. The tools used for designing
digitalized historical archives are based on an ontology that enables an
overview of the domain of interest, browsing by displaying texts and images,
and querying by making a specific request for
information from a database or choosing parameters from a menu. The collection
of historical data includes research in primary (such as archives, mail, and
books) and secondary materials. There is a need for tools for location and
visualization of such information, along with a study on the users' needs and
requirements. Katifori, Torou, Vassilakis, & Halatsis* (2008, pp. 32-37) performed such user study
and proposed a set of tools to aid research in the context of historical
archives, which present the display restricted to classes and relationships
pertaining to a specific time period, visualize a timeline and its evolution,
and show interdependencies of historical entities and events.
Figure 26. Bogdan Soban. Flower 2. Generative program based on the
deformation of the Mandelbrot fractal.
Visual Analytics
Visual analytics is the science that
supports analytical reasoning facilitated by interactive visual interfaces
(Thomas & Cook, 2008, 2006). Integration of explorative data
analysis tools and interactive visualization tools enable analytical reasoning
and collaboration. Visual analysts developed a number of interactive
visualization tools, many of them designed from the users’ point of view. Pixel-based
visualization techniques presenting the long-term behavior of large
amounts of financial data for long-term investmentscan support
the decision making process for investors on the financial market. A pixel-based paradigm for visual
analysis is not restricted to analyzing financial time series data but can be
used with any time series data. Ziegler, Nietzschmann,
& Keim* (2008, pp. 287-295) present the Performance Matrix, a visualization approach that demonstrates a pixel-based visualization technique
that integrates individual preferences of an investor and visually reflects the
regions of personal interest.
Figure 27. Helen Nicole Kotsis. Skin. Installation.
Matkovic, Freiler,
Gracanin, & Hauser* (2008, pp. 215-220)
present a ComVis, a new visualization technology based on the technology of the
coordinated multiple views. As an example, they present a configuration where
meteorological data can be examined with eight views, scatter plot, parallel
coordinates, histogram, color lines, curves, segmented curve view, and bar
charts.
Variables can be
described as categorical, ordinal, or interval. A categorical variable
(sometimes called a nominal variable) has two or more categories, but one
cannot clearly order the variables. There are
no operations such as addition or subtraction and no "less than" or
"greater than" relations among the nominal numbers. For example, gender (with two categories, male and female),
marital status, race, religious or political affiliation, college major, and
birthplace are examples of categorical variables
measured at a nominal level. Other examples include: geographical location in a
country represented by that country's international telephone access code, or
the make or model of a car. In
ordinal measurement there is a clear ordering of the variables. The
numbers called ordinals represent the
rank order (1st, 2nd, 3rd etc.) of the variables that are called ordinal
variables or rank variables.
However, the spacing between the
values may not be the same across the levels of the variables. Examples
are variables such as economic status (low, medium and high), a mineral
hardness scale, or the horse race results. The variable is called an interval
variable when the intervals between the values are equally spaced and the
differences between pairs of measurements can be
compared*.
Mixed data sets contain a
combination of categorical and continuous variables.Mixed data
sets exist in many research areas. They are difficult to analyze since no
generalized similarity measure exists for categorical variables. Sara
Johansson, Mikael Jern, and Jimmy Johansson*
(2008, pp. 3-10) present an interactive visualization environment where the user may
control and analyze the measuring of the quantities. It is possible to quantify
categorical data by assigning order and distance to categories. One may order
the categories manually; it is time consuming and the result depends on the
knowledge of the analyst. One may also use an algorithm to compute distance and
order categories. The authors present an approach that utilizes the efficiency
of an algorithm and makes use of the knowledge of a user. They present an
interactive quantification process for categorical variables in mixed data
sets.
A tag cloud is a type of visualization used to describe a website
content. Tag clouds are widely employed in social software (where users can
interact and share data) for labeling digital content of various Web 2.0
websites, such as photographs (Flickr, www.flickr.com),
videoclips (YouTube, www.youtube.com), and WWW bookmarks (www.del.icio.us). They
are also useful in browsing for topics. Tag maps are the text-based visual
representations of text in geographical space. Both depict each tag importance,
their weight by a font size, color, by popularity, or content. In order to
solve such issues as unused whitespace, restriction to certain bounding areas
(rectangle, circle), and the overlapping of tags, Seifert, Kump, Kienreich, Granitzer, & Granitzer* (2008, pp. 17-25) present four algorithms that change the tags' visual
representation by shifting the font size interval, scaling it, and truncating
the tags' strings. In terms of its aesthetic value, evaluation of the algorithm
usability evidenced the primacy of the shift-scale-trunc combination of the
steps.
Figure 28. Robert Fathauer. Fractal Tree
No 4. Graphical iteration of
an arrangement of a small portion of a photograph of a tree.
Summary and Conclusion
Topics selected for this review reflect
only a few selected themes related to the whole field of visualization,
information visualization, visual analytics, visual data mining, and other
fields that are now growing and get a lot of attention. Also, they do not cover
the broad spectrum of the 12th International Conference on
Information Visualization in London, UK. Specialized sessions held at the
Conference included: themes related to information visualization: theory,
techniques, usability, applications, web visualization, IV-coordinated and multiple
views in exploratory visualization; visual analytics: visual data mining and
analytics, open source intelligence and web mining, geo-analytics; themes
related to knowledge visualization: knowledge domain visualization, cultural
heritage knowledge visualization, design visualization, HCI-interaction design
for knowledge visualization, visualization in software engineering, and
applications of graph theory. Proceedings of the 12th International
Conference on Information Visualization, edited by Ebad Banissi, Liz Stuart,
Mikael Jern, Gennady Andrienko, Francis T. Marchese, Nasrullah Memon, Reda
Alhajj, Theodor G. Wyeld, Remo Aslak Burkhard, Georges Grinstein, Dennis Groth,
Anna Ursyn, Carsten Maple, Anthony Faiola, and Brock Craft, have been published
by IEEE Computer Society Press.
Figure 29. Dena Eber.
References
Bourqui, R., &
Jourdan, F. (2008). Revealing Subnetwork Roles using Contextual Visualization:
Comparison of Metabolic Networks. In iV, 12th International
Conference on Information Visualisation, London, UK (pp. 638-643). IEEE Computer Society Press.
Brath, R. (2008).
Use of Analogy in Synthesizing Novel Visualizations. In iV, 12th
International Conference on Information Visualisation, London, UK (pp.
481-484). IEEE Computer
Society Press.
Burkhard, R.,
Bischof, S. & Herzog, A. (2008). The Potential of Crowd Simulations for
Communication Purposes in Architecture. In iV, 12th International
Conference on Information Visualisation, London, UK (pp. 403-408). IEEE Computer Society Press.
Card, S.,
Mackinlay, J. & Shneiderman, B. (1999). Readings in Visualization: Using
Vision to Think. San Francisco, CA: Morgan Kaufman.
Chias, P., & Abad,
T. (2008). Visualising Ancient Maps as Cultural Heritage: A Relational Database
of the Spanish Ancient Cartography. In iV, 12th International
Conference on Information Visualisation, London, UK (pp. 453-457). IEEE Computer Society Press.
Ching-jung Lin,
& Jhong-Jyun Guo (2008). A Design Supporting System for Kimono Pattern
Preservation. In iV, 12th International Conference on Information
Visualisation, London, UK (pp. 458-461). IEEE Computer Society Press.
Clayton, S.,
Pinheiro, V., Meiguins, B. S., Simões, A., Meiguins, G. & Almeida, H. L (2008).
A Tourism Information Analysis Tool for Mobile Devices. In iV, 12th
International Conference on Information Visualisation, London, UK (pp.
264-269). IEEE Computer
Society Press.
Cottam, J. A.,
& Lumsdaine, A. (2008). Stencil: A Conceptual Model for Representation and
Interaction. In iV, 12th International Conference on Information
Visualisation, London, UK (pp. 51-56). IEEE Computer Society Press.
Craft, B., &
Cairns, P. (2008). Directions for Methodological Research in Information
Visualization. In iV, 12th International Conference on Information
Visualisation, London, UK (pp. 44-50). IEEE Computer Society Press.
Dokulil, J., &
Katreniakova, J. (2008). Navigation in RDF Data. In iV, 12th
International Conference on Information Visualisation, London, UK (pp. 26-31). IEEE Computer Society Press.
Dokulil, J., &
Katreniakova, J. (2008). RDF Query Generator. In iV, 12th
International Conference on Information Visualisation, London, UK (pp.
191-193). IEEE Computer
Society Press.
Dokulil, J. &
Katreniakova, J. (2008). Edge Routing with Fixed Node Positions. In iV, 12th
International Conference on Information Visualisation, London, UK (pp.
626-631). IEEE Computer
Society Press.
Empson, W. (1932). Seven
Types of Ambiguity. Cambridge: Cambridge University Press
Eppler, M. J.,
Mengis, J., & Bresciani, S. (2008). Seven Types of Visual Ambiguity: On the
Merits and Risks of Multiple Interpretations of Collaborative Visualizations.
In iV, 12th International Conference on Information Visualisation,
London, UK (pp. 391-396). IEEE
Computer Society Press.
Flynn, B. (2008).
Augmented Visualisation: Designing Experience for an Interpretative Cultural
Heritage. In iV, 12th International Conference on Information
Visualisation, London, UK (pp. 447-452). IEEE Computer Society Press.
Gatzidis, C.,
Papakonstantinou, S., Brujic-Okretic, V. & Baker, S. (2008). Recent
Advances in the User Evaluation Methods and Studies of Non-Photorealistic
Visualization and Rendering Techniques In iV, 12th International
Conference on Information Visualisation, London, UK (pp. 475-480). IEEE Computer Society Press.
Gaudin,
B. & Quigley, A. J. (2008). Interactive Structural Clustering of Graphs
based on Multi-Representations. In iV, 12th International Conference
Information Visualisation, London, UK (pp.227-232). IEEE Computer Society Press.
Giereth, M., &
Ertl, T. (2008) Visualization Enhanced Semantic Wikis for Patent Information.
In iV, 12th International Conference on Information Visualisation,
London, UK (pp. 626-631). IEEE
Computer Society Press.
Giordano, A.,
Bifulco, L., Lovato, R. & Barnes, C. (2008). Hypertext of the
Ecclesiastical Architectural Heritage of the Padova Historic Centre. In iV, 12th
International Conference on Information Visualisation, London, UK (pp.
433-438). IEEE Computer
Society Press.
Girot, C., & Truniger, F.
(2006). The Walker‘s Perspective: strategies for conveying landscape perception
using audiovisual media. Proceedings
of the 10th International Conference on Information Visualization, (pp. 225-231). IEEE
Computer Society Press.
Herr II B. W.,
Duhon, R. J., Börner, K., Hardy E. F., & Penumarthy, S. (2008). 113 Years
of Physical Review: Using Flow Maps to Show Temporal and Topical Citation
Patterns. In iV, 12th International Conference on Information
Visualisation, London, UK (pp. 421-426). IEEE Computer Society Press.
Jern, M.,
Rogstadius, J., Åström, T. & Ynnerman, A. (2008). Visual Analytics
Presentation Tools Applied in HTML Documents. In iV, 12th
International Conference on Information Visualisation, London, UK (pp.
200-207). IEEE Computer
Society Press.
Jern, M., Åström,
T., & Johansson, S. (2008). GeoAnalytics Tools Applied to Large Geospatial
Datasets). In iV, Proceedings of the 10th International Conference on
Information Visualization, (pp. 362-372). IEEE Computer Society Press.
Ji Soo Yi, Youn ah
Kang, Stasko, J. & Jacko, J. (2007). Toward a Deeper Understanding of the
Role of Interaction in Information Visualization. IEEE Transactions on
Visualization and Computer Graphics, (pp. 1224-1231).
Johansson, S.,
Jern, M.. & Johansson, J. (2008). Interactive Quantification of Categorical
Variables in Mixed Data Sets. In iV, 12th International Conference
on Information Visualisation, London, UK (pp. 3-10). IEEE Computer Society Press.
Katifori, A.,
Torou, E., Vassilakis, C. & Halatsis, C. (2008). Supporting Research in
Historical Archives: Historical Information Visualization and Modeling
Requirements. In iV, 12th International Conference on Information
Visualisation, London, UK (pp. 32-37). IEEE Computer Society Press.
Kianmehr, K., &
Alhajj, R. (2008). Effectiveness of Machine Learning Techniques for Automated
Identification of Calling Communities. In iV, 12th International
Conference on Information Visualisation, London, UK (pp. 308-313). IEEE Computer Society Press.
Kinsella, S.,
Bojars, U., Harth, A., Breslin, J. G. & Decker, S. (2008). An Interactive
Map of Semantic Web Ontology Usage. In iV, 12th International
Conference on Information Visualisation, London, UK (pp. 179-184). IEEE Computer Society Press.
Kriglstein, S.,
& Motschnig-Pitrik, R. (2008). Knoocks: New Visualization Approach for
Ontologies. In iV, 12th International Conference on Information
Visualisation, London, UK (pp. 163-168). IEEE Computer Society Press.
Kumar, P., Zhang,
K., & Wang, Y. (2008). Visualization of Clustered Directed Acyclic Graphs
without Node Overlapping. In iV, 12th International Conference on
Information Visualisation, London, UK (pp. 38-43). IEEE Computer Society Press.
Lammarsch, T.,
Aigner, W., Bertone, A., Miksch, S., Turic, T. & Johannes Gärtner, J. (2008).
A Comparison of Programming Platforms for Interactive Visualization in Web
Browser Based Applications. In iV, 12th International Conference on
Information Visualisation, London, UK (pp. 194-199). IEEE Computer Society Press.
Lundblad, P., Jern,
M., & Forsell, C. (2008).Voyage Analysis Applied to Geovisual Analytics. In
iV, 12th International Conference on Information Visualisation,
London, UK (pp. 381-388). IEEE
Computer Society Press.
Marchese, F. T.
(2008). The Chemical Table: An Open Dialog between Visualization and Design. In
iV, 12th International Conference on Information Visualisation,
London, UK (pp. 75-81). IEEE
Computer Society Press.
Matkovic, K.,
Freiler, W., Gracanin, D., & Hauser, H. (2008). ComVis: A Coordinated
Multiple Views System for Prototyping New Visualization Technology. In iV, 12th
International Conference on Information Visualisation, London, UK (pp.
215-220). IEEE Computer
Society Press.
Neri, F., &
Pettoni, M. (2008). Stalker, a Multilingual Text Mining Search Engine for Open
Source Intelligence. In iV, 12th International Conference on
Information Visualisation, London, UK (pp. 314-320). IEEE Computer Society Press.
Newlon, C. M.,
Faiola, A., & MacDorman, K. F. (2008). Building the Mega-Collaboration
Interface: Behavioral, Cultural, and Cognitive Factors in Visualization
Support. In iV, 12th International Conference on Information
Visualisation, London, UK (pp. 509-514). IEEE Computer Society Press.
Oka, M., &
Yutaka Matsuo. (2008). Mining Scholarly Semantic Networks from the Web. In iV,
12th International Conference on Information Visualisation, London,
UK (pp. 349-355). IEEE
Computer Society Press.
Pigozzi, M. (2008).
Photographs of Artworks: Electronic formatting of knowledge and the Internet.
In iV, 12th International Conference on Information Visualisation,
London, UK (pp. 462-465). IEEE
Computer Society Press.
Pumpa, M., & Wyeld,
T. G. (2006). Database and Narratological Representation of Australian
Aboriginal Knowledge as Information Visualisation using a Game Engine. In Proceedings of the iV, 10th
International Conference on Information Visualization, London, UK (pp. 237-2426). IEEE Computer
Society Press.
Rodgers, P., Zhang,
L., Stapleton, G. & Fish, A. (2008). Embedding Wellformed Euler Diagrams.
In iV, 12th International Conference on Information Visualisation,
London, UK (pp. 585-593). IEEE
Computer Society Press.
Seifert, C., Kump,
B., Kienreich, W., Granitzer, G. & Granitzer, M. (2008). On the Beauty and
Usability of Tag Clouds. In iV, 12th International Conference on
Information Visualisation, London, UK (pp. 17-25). IEEE Computer Society Press.
Thomas, J. J.,
& Cook, K. A. (2006, January/February). IEEE Computer Graphics and Applications, 26(1), 10-13.
Tominski, C., &
Schumann, H. (2008). Visualization of Gene Combinations. In iV, 12th
International Conference on Information Visualisation, London, UK (pp.
120-126). IEEE Computer
Society Press.
Tominski, C.,
Fuchs, G. & Schumann, H. (2008). Task-Driven Color Coding. In iV, 12th
International Conference on Information Visualisation, London, UK (pp.
373-380). IEEE Computer
Society Press.
Tomitsch, M.,
Grechenig, T., Vande Moere, A. & Renan, S. (2008). Information Sky:
Exploring the Visualization of Information on Architectural Ceilings In iV, 12th
International Conference on Information Visualisation, London, UK (pp.
100-105). IEEE Computer
Society Press.
Trapp, M., Glander,
T., Buchholz, H. & Döllner, J. (2008). 3D Generalization Lenses for
Interactive Focus + Context Visualization of Virtual City Models. In iV, 12th
International Conference on Information Visualisation, London, UK (pp.
356-361). IEEE Computer
Society Press.
Vande Moere, A.
(2008). Beyond the Tyranny of the Pixel: Exploring the Physicality of
Information Visualization. In iV, 12th International Conference on
Information Visualisation, London, UK (pp. 469-474). IEEE Computer Society Press.
Wyeld, T. (2008).
Encoded Cultural Heritage Knowledge in Australian Aboriginal Traditional
Representation of Country. In iV, 12th International Conference on
Information Visualisation, London, UK (pp. 439-446). IEEE Computer Society Press.
Ziegler, H.,
Nietzschmann, T., & Keim, D. A. (2008). Visual Analytics on the Financial
Market: Pixel-based Analysis and Comparison of Long-Term Investments. In iV, 12th
International Conference on Information Visualisation, London, UK (pp.
287-295). IEEE Computer
Society Press.