Serendipity: Vision to think...

Stunning soccer skills

Tue, 24 Feb 2009 15:51:08 -0500

How to flourish in graduate school

Fri, 14 Nov 2008 21:55:07 -0500

This week, our team present the different aspects of a successful graduate school life. My teammate give a good summary of those perspectives, which is shown in follow picture.

PhD Life. Source:Team 10

The different aspects of PhD life includes motivation, academia business, game rules, initiative, tenacity, flexibility, interpersonal skills, organizational skills, communication skills, balance& perspective. Here I won't go into the details about these, and the essay about this could be found here.

I would mention here is the tricks and lessons I learned from others during the class discussion about motivation and organization skills.
One trick about motivation, Dr. Tapia shared with us is to motivate yourself with reward of pleasure. Once you wanna socialize with your friends, or relax yourself, you can first set a goal to finish some work and then reward your work with the social activities or other recreation. This method works for me: every Sat. afternoon I can't wait for playing soccer with some friends, but before that, in that morning, I will encourage me to finish a certain work and then go to the field.
For the motivation, punishment never works. Sometime, we use punishment to make up our watse of time. For example, because I watch a movie and take up the time to finish some works, I would punish myself to sleep late to finish the work. However, this doesn't work each time. It just make you feel more inefficient and guilty about yourself.

"Kill your television", Randy Pausch

How to manage your time? Dr. Tapia said she would like to finish difficult thing in the morning, like writing, and do some easier work at night. This could be a good strategy, because in morning, we could work more efficient, and after finishing the tough things, you will be confident about the rest of the day.
Another trick about time management discussed in class is to never make your work and leisure get touched. This means that at home you just get relaxed, have dinner, and chat with your roommates, and your office is the place you work. Never think that you can work and finish something at home. That would be very inefficient.

The final thing I agree with is that "Graduate school isn't worth risking your personal relationships over". Indeed, we need to save time and energy to focus on the people who matter to you.

People matter to you, Source: Here.

Flex Component Life Cycle

Wed, 12 Nov 2008 20:51:27 -0500

tTo understand the life cycle of a flex component, a counter example I made is a good start point. Say we have a customized component "ImageThumbnail":

Then in our main application, we would like to create an instance of this component with a customized image URL, and add it into a Tile ("tlTop"). First I wrote like this:

private var thumb :ImageThumbnail=new ImageThumbnail();
thumb.imageHolder.source="data/icon.jpg";
tlTop.addChild(thumb);

I got an error like this:

TypeError: Error #1009: Cannot access a property or method of a null object reference.

When I was tracing the code, I found that the "thumb.imageHolder" is null even after I use new method to initialize the ImageThumbnail explicitly. However, after I wrote the code like this:

tlTop.addChild(thumb);
thumb.imageHolder.source="data/icon.jpg";

It works!

This is because of the special mechanism of the life cycle of Flex components. Following traditional programming logic, because the "Image" component is a child of "ImageThumbnail", thus after we explicitly initialize "ImageThumbnail", the "Image" should be also initialized. However, this is not what Flex works!

In Flex, the first time addChild() or addChildAt() is called, the component's initialize() method also gets called - FlexEvent.preinitialize is dispatched, the rest of the code in initialize() method is run, FlexEvent.initialize is dispatched, then createChildren() is called (in which the UITextField is created for use as the button's label ... and so on. If your component has children which are UIComponents, then the process will be recursive.

Method .addChild() is where it all starts to come together.

To understand more about the component life cycle, a good article can be found here, and this one is also highly recommended.

Global Connections

Fri, 07 Nov 2008 22:09:59 -0500

Global Connections Source:http://www.international.psu.edu/IHC/

Global Connections is a community non-profit organization, affiliated with the Pennsylvania State University and the Centre County United Way, with a long-standing tradition of promoting international cultural exchange in Centre County.

The mission of this program is described in following picture, which focus on cross-cultural communication.

Global Connections: Mission Statement Source:http://www.international.psu.edu/IHC/

It has several programs:

Global Connections works with:
* International students and scholars, and their families at Penn State University
* The employees of international companies in Centre County, and
* Recent immigrants
The first time I know the program of "Global Connections" is when I was in the middle of orientation. With the expectation of improving my communication skills, I filled some registration form and enrolled the Conversation Partners Program program. This program matches native speakers of English with non-native speakers of English on campus and in the community for the purpose of language practice and cultural exchange. Soon I got conversation partners, who are a couple living about 10 miles away from PSU. They are very nice couple. Via this program, I not only made some improvement of my language, but also gained a lot of native culture experiences.

Mon, 03 Nov 2008 00:32:36 -0500

"Visualization is a method of computing. It transforms the symbolic into the geometric, enabling researchers to observe their simulations and computations. Visualization offers a method for seeing the unseen. It enriches the process of scientific discovery and fosters profound and unexpected insights. In many fields it is already revolutionizing the way scientists do science." (McCormick et al., 1987)

About George W. Furnas

Fri, 31 Oct 2008 19:47:54 -0500

At this time, I would like to introduce, a notable researcher in HCI, George W. Furnas. Technically speaking, he is my adviser's adviser. George is Professor and Associate Dean in the School of Information at the University of Michigan with additional appointments in Psychology and Computer Science.

George W. Furnas. Source: Furnas' Home Page.

Dr. Furnas obtained AB in cognitive psychology, Harvard University and Ph.D. in cognitive psychology, Stanford University. Prior to join in University of Michigan, Furnas worked at Bell Labs for 15 years where he was a researcher and manager.

As for his contribution to HCI, let's have a look at the delineation from SIGCHI Academy 04':
" A principal focus of his research is in advanced information access and visualization. His early role in the analysis of the "Vocabulary Disagreement" problem lead to his co-invention of Latent Semantic Analysis for indexing and text processing. His classic "Generalized Fisheye Views" paper inspired a sea of focus+context research in information visualization. George's BITPICT graphical rewrite system is well known novel contribution to diagrammatic reasoning, visual languages and visual programming communities. George was also an early researcher in the areas of collaborative filtering,and graph visualization. His "Space-Scale Diagrams in the Pad++ Zoomable User Interface" advanced the analysis of zoomable user interfaces, and View Navigation theory has helped motivate much subsequent research in Information Scent."

The Fisheyes Views, one significant technique in information visualization, earned its fame as Furnas worked in Bell Labs 26 years ago. Right now, it is till widely cited paper in HCI field. Fisheyes Views technique enlarge the focal part and shrink the non-focal parts, which enable users to access the details information as well as having a sense of contextual information.A commonly used example of Fisheyes Views the Dock in Macintosh OS.

Apple Dock. Source: Apple.com.

This technique is important for large social network visualization, one of my current research foci. For the visualization of large social network, one big problem is that When the size of a network becomes large, it is not agreeable to display all nodes and edges at the one time, because the limit of screen real estate constraints a user's ability of comprehension of the layout and interaction with the network. Fisheyes Views provides a general framework to enable user focus on the information of interest. This method is very easy to be generalized into network visualization and works fine for multiple foci.

My Publication/Presentation Outlets

Fri, 24 Oct 2008 23:58:39 -0500

In this blog, I would like to introduce some publication/presentation venues I hope to have my work in, including ACM SIGCHI, ACM UIST, and IEEE InfoVis.
SIGCHI, as mentioned in the previous post, is the ACM (Association for Computing Machinery)'s Special Interest Group on Computer-Human Interaction. SIGCHI is a top conference in HCI community. Let's have a look at two figures about submission and acceptance recently:

CHI Submission and Acceptance Data. Source Here.

CHI Acceptance Rate. Source Here.

Obviously,SIGCHI, is getting more and more researchers involved, and the acceptance rate keeps a rather low level to guarantee its quality.
As for me, has a subcommittee focusing on "Interaction using Specific Capabilities or Modalities". This subcommittee is to advance "the interaction which are enabled by technologies, modalities, or capabilities which have not been fully exploited in traditional approaches to interaction". Some keywords are

Visualization
Perception and Vision-base UIs

This direction is very research topics I am interesting in.

UIST (ACM Symposium on User Interface Software and Technology) is another top conference in HCI community sponsored by ACM, but focuses on innovations in the software and technology of human-computer interfaces. It is pretty new but notable conference, which earns a lot attention since 2003:

UIST Submission and Acceptance Data (Left), UIST Acceptance Rate (Right). Source Here.

One topic of UIST is traditional graphical & web user interfaces. When visualizing the data, the interface also would be an important factor for users.

IEEE InfoVis focuses on more computer sides in term of information visualization, such as the graphics, algorithms, novel visual techniques. In this sense, it likes UIST. For me, I feel some network layout and interaction algorithms in this confernce are very interesting. In future, I will aslo work on some issues about the layout and intercation techniques of huge network data.

My academic communities

Fri, 17 Oct 2008 14:44:57 -0500

Here, I would like to introduce four academic communities: three of them are conference-based communities: ACM SIGCHI, ACM UIST, IEEE InfoVis, and one is a journal-based community: TOCHI.

The first two conference-based communities are under ACM (Association for Computing Machinery), which is "the world's largest educational and scientific computing society, delivers resources that advance computing as a science and a profession".

Association for Computing Machinery. Source:http://www.acm.org

ACM has a bunch of Special Interest Groups which offers a wealth of conferences, publications, and activities, providing unlimited opportunities for sharing technical expertise and first-hand knowledge of the latest development trends.

SIGCHI, is the ACM (Association for Computing Machinery)'s Special Interest Group on Computer-Human Interaction.

ACM SIGCHI. Source:http://www.sigchi.org

It is oriented to "bring together people working on the design, evaluation, implementation, and study of interactive computing systems for human use". In this community, there are a lot famous names in the area of HCI. We can have a general idea from the list of receivers of CHI Lifetime Achievement Award:

	CHI Lifetime Achievement Award
1998	Douglas C. Engelbart
2000	Stuart K. Card
2001	Ben Shneiderman
2002	Donald A. Norman
2003	John M. Carroll
2004	Tom Moran
2005	Tom Landauer
2006	Judith Olson and Gary Olson
2007	James D. Foley
2008	Bill Buxton

UIST (ACM Symposium on User Interface Software and Technology) is another conference sponsored by ACM's special interest groups on computer-human interaction (SIGCHI). It is "the premier forum for innovations in the software and technology of human-computer interfaces".
IEEE (Institute of Electrical and Electronics Engineers) is an international non-profit, professional organization for the advancement of technology related to electricity.

Association for Computing Machinery. Source:http://www.acm.org

IEEE InfoVis is the premier forum for visualization advances in science and engineering for academia, government, and industry. This event brings together researchers and practitioners with a shared interest in techniques, tools, and technology.

TOCHI(ACM Transaction On Human-Computer Interaction) seeks to be the premier archival journal in the multidisciplinary field of human-computer interaction. Since its first issue in March 1994, it has presented work of the highest scientific quality that contributes to the practice in the present and future. The primary emphasis is on results of broad application, but the journal considers original work focused on specific domains, on special requirements, on ethical issues -- the full range of design, development, and use of interactive systems.

Why make sense for me?
Right now, I am focusing on information visualization about social network data, especially how visualization and interaction techniques could facilitate people's understanding of social network in a large scale. For me, SIGCHI is relevant because a part of SIGCHI focuses on users' interaction using specific capabilities or modalities to see how their novelty and their ability to extend user capabilities in powerful new ways, or to new contexts. For example, the big names mentioned above, such as Stuart K. Card, Ben Shneiderman, are the pioneers of information visualization and still very active in the field of information visualization.UIST, bringing together researchers and practitioners from diverse areas that include "traditional graphical & web user interfaces, tangible & ubiquitous computing, virtual & augmented reality, multimedia, new input & output devices, and CSCW", is an important community for me to learn some pratical and novel interface techniques. IEEE InfoVis is dedicated to the field of information visualization, helping people explore or explain data through interactive software that exploits the capabilities of the human perceptual system. TOCHI is a top journal in HCI, which covers the software, hardware and human aspects of interaction with computers. Of course, user interface design, visualization are the mainstream topics.

Microsoft Sliverlight 2

Wed, 15 Oct 2008 00:49:55 -0500

Silverlight. Source:http://silverlight.net/

Last September Microsoft shipped Silverlight 1.0 for Mac and Windows, and announced our plans to deliver Silverlight on Linux. Today, they release the first public beta of Silverlight 2, which will be a major update of Silverlight that focuses on enabling Rich Internet Application (RIA) development.

Cross Platform / Cross Browser .NET Development

Silverlight 2 includes a cross-platform, cross-browser version of the .NET Framework, and enables a rich .NET development platform that runs in the browser. Developers can write Silverlight applications using any .NET language (including VB, C#, JavaScript, IronPython and IronRuby). We will ship Visual Studio 2008 and Expression Studio tool support that enables great developer / designer workflow and integration when building Silverlight applications.

This upcoming Beta1 release of Silverlight 2 provides a rich set of features for RIA application development. These include:

WPF UI Framework: Silverlight 2 includes a rich WPF-based UI framework that makes building rich Web applications much easier. In includes a powerful graphics and animation engine, as well as rich support for higher-level UI capabilities like controls, layout management, data-binding, styles, and template skinning. The WPF UI Framework in Silverlight is a compatible subset of the WPF UI Framework features in the full .NET Framework, and enables developers to re-use skills, controls, code and content to build both rich cross browser web applications, as well as rich desktop Windows applications.

Rich Controls: Silverlight 2 includes a rich set of built-in controls that developers and designers can use to quickly build applications. This upcoming Beta1 release includes core form controls (TextBox, CheckBox, RadioButton, etc), built-in layout management panels (StackPanel, Grid, Panel, etc), common functionality controls (Slider, ScrollViewer, Calendar, DatePicker, etc), and data manipulation controls (DataGrid, ListBox, etc). The built-in controls support a rich control templating model, which enables developers and designers to collaborate together to build highly polished solutions.

Rich Networking Support: Silverlight 2 includes rich networking support. It includes out of the box support for calling REST, WS*/SOAP, POX, RSS, and standard HTTP services. It supports cross domain network access (enabling Silverlight clients to directly access resources and data from resources on the web). Beta1 also includes built-in sockets networking support.

Rich Base Class Library: Silverlight 2 includes a rich .NET base class library of functionality (collections, IO, generics, threading, globalization, XML, local storage, etc). It includes rich APIs that enable HTML DOM/JavaScript integration with .NET code. It also includes LINQ and LINQ to XML library support (enabling easy transformation and querying of data), as well as local data caching and storage support. The .NET APIs in Silverlight are a compatible subset of the full .NET Framework.

Below are the pointers to the 8 tutorials I've put together:

Part 1: Creating "Hello World" with Silverlight 2 and VS 2008

Part 2: Using Layout Management

Part 3: Using Networking to Retrieve Data and Populate a DataGrid

Part 4: Using Style Elements to Better Encapsulate Look and Feel

Part 5: Using the ListBox and DataBinding to Display List Data

Part 6: Using User Controls to Implement Master/Details Scenarios

Part 7: Using Templates to Customize Control Look and Feel

Part 8: Creating a Digg Desktop Version of our Application using WPF

IST Senior Student: Bi Chen

Fri, 10 Oct 2008 21:28:36 -0500

Here, I am pleasure to introduce Bi Chen, 陈碧, in Chinese, a 3rd PhD. student working with Dr. Xiaolong (Luke) Zhang, the same advisor as me.
Bi entered IST as a doctoral student in IST in 2006. Prior to that, he earned his B.S and M.S in computer science and communications at Zhejiang University, a beautiful university in China (See figure bellow).

ZhiJiang University. Source:http://www.zju.edu.cn

At that time, he began pursuing the topic how to utilize computing techniques predict and leverage social behaviors. Right now, he is working on his dissertation proposal.

He has attended 3 conferences: 15th IEEE International Workshops on Enabling Technologies: Infrastructures for Collaborative Enterprises (WETICE 2006), 26-28 June 2006, Manchester, United Kingdom; IEEE International Conference on Data Mining (ICDM 2007); and 22nd AAAI Conference on Artificial Intelligence (AAAI 2007), July 22-26, 2007, Vancouver, British Columbia, Canada. The conferences he attended focus on data mining and artificial intelligence.

3 publications have been done by Bi so far (some details can be obtain via DBLP):
1. Bi Chen, He Tan, Patrick Lambrix: Structure-Based Filtering for Ontology Alignment. WETICE 2006: 364-369
2. Bi Chen, Qiankun Zhao, Bingjun Sun, Prasenjit Mitra: Predicting Blogging Behavior Using Temporal and Social Networks. ICDM 2007: 439-444
2006
3. Qiankun Zhao, Prasenjit Mitra, Bi Chen: Temporal and Information Flow Based Event Detection from Social Text Streams. AAAI 2007: 1501-1506

He orients himself more on the technical vertex of the Great Triangle of IST, but also incorporating social factors. This is easily perceived from his recently publication and dissertation topic, which is about modeling social behavoirs, especially in social networks, with data mining techniques. Right now, he is also considering more human factors and interactions when constructing data mining model.

Sharedegg in SNs. Source:http://sharedeggg.blogspot.com/

Academically, I can benefit a lot from his work. My research interest is also about social networks sense making, but from another perspective: information visualization. I am trying to utilize network visualization and interaction techniques to understand the huge social network data. A big challenge here is how to employ the semantic data attached to the actors in social networks to facilitate the understanding of social networks when visualizing them. A potential solution is to extract the semantic content and also consider the structure of social network to leverage the visual representation of social networks and data attached them. In this sense, the data mining techniques, combining some linguistic computation techniques could offer me a good venue to address this issue. This area is exact strength of Bi Chen's works.

The Second Coming

Sat, 04 Oct 2008 21:53:42 -0500

The Second Coming
Turning and turning in the widening gyre The falcon cannot hear the falconer; Things fall apart; the centre cannot hold; Mere anarchy is loosed upon the world, The blood-dimmed tide is loosed, and everywhere The ceremony of innocence is drowned; The best lack all conviction, while the worst Are full of passionate intensity. Surely some revelation is at hand; Surely the Second Coming is at hand. The Second Coming! Hardly are those words out When a vast image out of Spiritus Mundi Troubles my sight; somewhere in sands of the desert A shape with lion body and the head of a man, A gaze blank and pitiless as the sun, Is moving its slow thighs, while all about it Reel shadows of indignant desert birds. The darkness drops again; but now I know That twenty centuries of stony sleep Were vexed to nightmare by a rocking cradle, And what rough beast, its hour come round at last, Slouches towards Bethlehem to be born?	5 10 15 20

Printings: The Dial (Chicago), November 1920; The Nation (London), 6 November 1920; Michael Robartes and the Dancer (Dundrum: Cuala, 1921); Later Poems (London: Macmillan, 1922; 1924; 1926; 1931).

How to layout clustered networks interactively?

Thu, 02 Oct 2008 16:02:22 -0500

How to layout clustered networks interactively?
Here, by "interactively", I mean when laying out the clustered networks with hierarchic information, we need to present them at different levels of details in both top-down and bottom-up ways, and at the same time, we can interact the clustered networks by dragging, adding, deleting,grouping, ungrouping, and fixed+focus(explain in details later) at corresponding levels. One critical thing during the interactive layout is to balance the aesthetic criteria and preserve the mental map [1] or dynamic stability [2]. This indicates that the relative locations of the clusters and the vertices at different levels should be preserved to the coherence of the representation, while allowing interaction with the layout.

Yaniv Frishman [3] presents a method drawing clustered graphs dynamically, which emphasizes maintaining the clustered structure of the graph during incremental layout. The strength of this method is that it works online and allows arbitrary modifications to the graph. This feature is what I need in my project.
Although this article doesn't articulate the details well, but the key ideas are helpful, summarized as follows:
1). Dummy vertices and edges are used in order to create a clustered structure.
2). Invisible place-holder vertices are used in order to minimize the movement of clusters and of vertices within clusters.
3). Edge length and weight are used as a means of controlling the changes made to the layout.
4). The set of vertices is partitioned into two subsets-stable and movable.
Point 1) is obvious in our case. Dummy vertices and edges are the nodes and edges of parent clusters.
Point 2) seems unnecessary for us.
Point 3) could be included to our project, in which we aggregate the weight of edges at different levels and consider the weight when initiating a force-directed layout. This is because here we probably adopt a traditional divide-and-conquer method [4], in which the clusters are first laid out separately and then composed together. However, this method neglects inter-cluster edges( A solution is discussed in [5]. I will explore this later).
Based on this, here is the basic idea to layout clustered networks interactively:
1). Initially layout the top level of clusters (not the root node) with external Forced-Direct model, the green, gray and purple nodes in Figure 1. The bound of node is proportional to the size (the number of child clusters) of a cluster, and the child clusters will be laid out within the bound of their parent node. The aggregated weight of the inter-cluster edges are also applied to layout.The centers and radius should be stored as the reference for next step.

Figure1. Graph Hierarchy and Graph. Source: Daniel, A., A. David and et al. [6]

2). The child clusters are laid out within the bound of their parent node with internal Forced-Direct model. At this stage, the layout should consider the inter-cluster connections.
3). Virtual Forced-Direct model will be applied to some discrete nodes within a cluster.
4). If occlusion occurs in child clusters, the radius will be enlarged, and the center will be proportionally moved.

Another paper, GrouseFlocks [6], relevant to our work, allows users to explore several different possible hierarchies on the same graph with domain-specific attributes. They offer us some strategies about Hierarchy Selection and Modification, which are important function for our project. The different cut of hierarchy is helpful for refining the "fix+focus" operstion coined by me. However, this paper doesn't address the multi-scale view and exploration of the clustered networks.

[1] K. Misue, P. Eades, W. Lai, and K. Sugiyama. Layout adjustment and the mental map. Journal of Visual Languages and Computing, 6(2):183-210, 1995.
[2] S. C. North. Incremental layout in dynadag. In F. J. Brandenburg, editor, Proc. 3rd Int. Symp. Graph Drawing (GD 1995), number 1027 in Lecture Notes in Computer Science, LNCS, pages 409-418. Springer-Verlag, 1995.
[3] Yaniv, F. and T. Ayellet, Dynamic Drawing of Clustered Graphs, in Proceedings of the IEEE Symposium on Information Visualization. 2004, IEEE Computer Society.
[4] Ralf, B. and C. Sabine, Drawing clusters and hierarchies, in Drawing graphs: methods and models. 2001, Springer-Verlag. p. 193-227.
[5] X. Wang and I. Miyamoto. Generating customized layouts. In F. J. Brandenburg, editor, Proc. 3rd Int. Symp. Graph Drawing (GD 1995), number 1027 in Lecture Notes in Computer Science, LNCS, pages 504-515. Springer-Verlag, 1996.
[6] Daniel, A., M. Tamara, and A. David, GrouseFlocks: Steerable Exploration of Graph Hierarchy Space. IEEE Transactions on Visualization and Computer Graphics, 2008. 14(4): p. 900-913.

To read:
[1] Eades, P. and M.L. Huang, Navigating Clustered Graphs using Force-Directed Methods.
[2] Balzer, M. and O. Deussen, Level-of-detail visualization of clustered graph layouts. 2007.

About Dr. Xiaolong Zhang

Sat, 27 Sep 2008 00:32:57 -0500

Dr.Xiaolong Zhang. Source:http://zhang.ist.psu.edu

All this entry is the story about Dr. Xiaolong (Luke) Zhang, in Chinese, my adviser.

Xiaolong is originally from Taiyuan, the capital city of Shanxi Province (Chinese: 山西), in the northern part of China. After high school, he went to Tsinghua University, and obtained his Bachelor and Master degree of Engineer there. He then arrived U.S. and earned his Ph.D from University of Michigan, Ann Arbor, specialization in Human-Computer Interaction (HCI).

Taiyuan in China. Source:wikipedia

Before I arrived Penn State, I knew him via his academic website in IST. After I met him personally here, I found that he is even much nicer than the one on the photo (up left) from his website. During the-nightmare-first-year, when I was struggling to my research direction and research adviser, he generously offered me a lot of help and suggestions. With his help, I anchored my real research interest and decided to work with him.
Even before we worked together, we got known with each other on soccer field. He is a definite soccer enthusiast. So am I. The first time I played soccer with him, I was surprised that he is a so energetic and passionate soccer player. At that time, I even didn't know he is a faculty of IST and also I can't imagine I will work with him. Right now, we regularly play soccer together with CFA Soccer Club every Sat. afternoon. On the field, we are teammates; off field, we are friends; and in IST, we work togeter and he is my adviser. This could be called my fortune in life.
Dr.Zhang has a happy family. He met his wife, Fang Wan, in Beijing. He has a cute daughter.

Multilevel Clustered Graph Drawing

Thu, 25 Sep 2008 22:24:54 -0500

Eades Peter et al. [1] present a bottom-up method to draw multilevel clustered graphs. Their approach is to construct a skeleton for each cluster. The skeleton consists of the vertices and edges the outer faces of the child clusters. Then they recursively apply this to every level. A sample looks like this:

An example of Multilevel Visualization of Clustered Graphs. Source: Peter, Eades. et al.[1]

The layout criteria they pursue here is called C-Planarity, which means there are no edge crossings or edge-region crossings. In his recent article [2], he also follows this criteria and solve the problem of existence of C-Planarity of Hierarchical Graphs, and presents an algorithm construct such drawings in linear time.

A c-planar clustered graph. Source: Peter, Eades. et al.[2]

This strand of graph drawing is very appealing to the layout of multi-scale view of network. It offers us some rules of thumb to follow. However, there are some issues they did not solve:

This method is bottom-up. In our case, we need both bottom-up and up-bottom layout of clustered graph.
Interaction Problem. To enable users explore the network at different details, such as drag and place any points at their mercy, we need to update the whole layout from time to time. This problem will be deepened when the layout is up-bottom.
Another problem is that both [1] [2] follows an layout algorithm of Tutte's [3], which guarantee the rule of C-Planairty, but inappropriate for networks.

One of Eades's student, Huang, M.L., gave us some interesting solution of the last issue-A Spring Model in Clustered Graphs [4]. They defined three types of spring forces:

internal-spring: A spring force between a pair of vertices in the same cluster.

external-spring: A spring force between a pair of vertices in dierent clusters.

virtual-spring: A spring force between a vertex and a virtual (dummy) node along a virtual (dummy) edge.

A Spring Model in Clustered Graphs. Source: Huang, M.L. and P. Eades [4]

Unfortunately, they just published a short paper and no detailed description of this model. However, this model could be extended into our model.

References
1. Eades, P. and Q.-W. Feng, Multilevel Visualization of Clustered Graphs, in Proceedings of the Symposium on Graph Drawing. 1997, Springer-Verlag.
2. Eades, P., et al., Straight-Line Drawing Algorithms for Hierarchical Graphs and Clustered Graphs. 2006, Springer. p. 1-32.
3. Tutte, W.T., How to draw a graph. 1963. p. 743-768.
4. Huang, M.L. and P. Eades, A fully animated interactive system for clustering and navigating huge graphs. 1998, Springer. p. 374-383.

What is IST?

Fri, 19 Sep 2008 21:54:59 -0500

IST Philosophy Tree. Source:http://ist.psu.edu

"Human nature is not a machine to be built after a model, and set to do exactly the work prescribed for it, but a tree, which requires to grow and develop itself on all sides, according to the tendency of the inward forces which make it a living thing."-John Stuart Mill, On Liberty (1859)

This is what we can see in the huge banner hanging in the grand hall of IST building. The first time I first walked through the hallway of IST building, the huge blue banner totally seized my sight. It impressed me a lot and offered me a preliminary idea of IST. However,what does the tree stands for and what is the tree of IST?
The right picture of IST Research Philosophy is the best explanation of the tree of IST, which is the integrated, an interdisciplinary program. What makes the tree a live things comes from a wide set of domains ranging from traditional elements of computer science, engineering, psychology, social sciences, economy, and information science, in short, GIANT TRIANGLE-INFORMATION,PEOPLE,TECHNOLOGY. Absorbing nutrition from this great triangle, IST is carrying out its mission-"change the world with inspired solutions, humanized technologies, and informed people". The three aspects are radiated from each sides of the triangle.
The paradigm of IST furnish us a unprecedented diverse platform, on which everyone among us could find right place to give others great performance. We are nourished from the basic constructs of information, technology and people, and understand methodologies associated with both quantitative and qualitative research. This would open our eye sights to a wide picture beyond any other research paradigm could offer us. However, the issue raised here is that how to seat ourselves within this triangle. Is it necessary to embraces all three vertexes into our research or just two of them? If I only follow two strands of them, do I betray the philosophy and mission of IST? I guess it is hard to answer, as one can't tell whether the paradigm itself is successful or not.
Before I arrived here, I am a kind of technical guy with little preference of information. Some times, I am so fascinated with the aesthetic of information technologies. With emergence of social force in information technologies, such as web2.0, social networking services, I realized the intrinsic connections of human sides with information and technologies. Right now, I am working with Dr. Xiaolong Zhang on information visualization. By the invention of external cognition aids, visualization artifacts make the information more understanding to us. With the augment of information visualization technology, I focus on the human's interaction with visual representation of information. In this sense, I am kind of seating myself in the center of IST giant triangle.

IST Building. Source:http://wang.ist.psu.edu/