Wenhang Li finished his doctoral thesis defense successfully on June 10, 2007.

Thu, 14 Jun 2007 13:59:00 GMT

Wenhang Li finished his doctoral thesis defense successfully on June 10, 2007. His doctoral dissertation is entitled “Study on Theories and Key Technologies for Collaborative Virtual Geographic Studio ” .

This is his doctoral thesis summary:

Study on Theories and Key Technologies for Collaborative Virtual Geographic Studio

Abstract

Geographic system is one open complex giant system, which indicates that new methods are needed for complex geographic issues solution. Collaborative Virtual Geographic Studio (CVGS) was then proposed, based on thought of collaboration from CSCW (Computer Supported Cooperative Work) and CVE (Collaborative Virtual Environment), thought of mobile work from mobile technology, and thought of complexity solution from metasynthesis and hall for workshop of metasynthetic engineering.

CVGS is one distributed three-dimensional platform for group discussion on geographic issues. It is one human-centered human-computer system, composed of Internet and mobile network, computers and mobile instruments involved.

CVGS is studied from three levels of theory, techniques and application in this paper, the main content are:

l At the theory level. (1) “Role theory” is proposed for social property of group participants. In group discussion, participants have different “social status”, play different “roles”, have different “rights”, as well as different “obligations”, and build up different “relationship” on basis of these. (2)The “5A” model is proposed for geographical researches from view of group participation. “5A” is Anyone, Anytime, Anywhere, Anything and Association. The flexible “5A” model has little restriction with participants, space (including movement status), time (in discussion period), and the content of geographic issues. All these are done with tight association between each other. (3) A 4-part group discussion process is proposed: collaborative reconstruction for geographic issues, collaborative analysis for geographic data, group discussion, and decision-making. The process is a positive feedback cycle. At the same time, measures for “concept conflict”, “language conflict”, “group thinking”, and “emergency” are emphasized. (4) Study on geo-ontology. It is pointed out that geo-ontology is different from other ontology because of its spatial characters. So it is suggested that ontology would have its scope extended when applied into geography. Meanwhile, the paper notes that ontology (including geo-ontology) should combine with graph theory for knowledge expression, and more important, for knowledge calculation visually with support of graph theory. “Knowledge Topology Network (KTN)” is then prospected.

l At the technique level. CVGS is positioned as a heterogeneous system, composed with heterogeneous networks of Internet and mobile network, with heterogeneous clients of computers and mobile instruments. Asymmetry is the obvious property of CVGS, with computation capability asymmetry, storage capability asymmetry, and display capability asymmetry as typical ones. To make CVGS agree with the concept of “Collaboration”, computation transfer and storage transfer between different terminals are proposed. Key technologies are as follows: (1) Three-dimensional scene collaboration among heterogeneous terminals. It is still a hard work to simulate 3-dimensional, let alone collaboration with computer. To solve this problem, “Stream media based collaboration” is proposed. The main idea is that to transfer computation requirement from mobile instruments to computer to render the complex content of the 3-dimensional virtual scene, and send the result back as a stream. Complex virtual scene contents, such as particle systems, multi-agent systems, and videos can then be simulated on mobile instruments. (2) Long-time connection maintenance mechanism for mobile instruments. Mobile instruments have the so-called “roll-back effect” which makes mobile instruments unable to keep network connection. This is unsuitable for choose mobile instruments as one part of CVGS. To solve this problem, “long-time connection maintenance” is proposed, that is, to separate sent-messages from gotten-messages to avoid the “roll-back effect”. The mechanism enables mobile instruments long-time collaborations with computer during geographic issues discussion.
As to the group interaction, workflows in collaborative issue reconstruction, collaborative data mining, multi-perceptive group interactions, and group decision-making are studied. Key technologies such as CVGS data organization, scene consistency maintenance, right assignment and other techniques are studied. Based on the above technologies, a CVGS prototype has been programmed using Java SE, Java ME, and Java 3D.

l At the application level. “Dam system planning project judgment” is chosen as the case for CVGS application. Dam system is one of the vital measures for water and soil conservation for loess plateau and for health of Yellow River, while dam system planning project judgment is the final and key stage for dam system planning. Collaborative project judgment is first proposed according to “5A” model, which is to involve experts, workers, and citizens, wherever they are, and whatever their movement status, to make comments on different projects, and to select the best one among those projects. Group discussion steps, collaborative issue reconstruction, collaborative data analysis, social group interaction, and project selection are all test. The result shows that it is feasible.

Key words: Group geographic research, geo-collaboration, distributed virtual environment, collaborative virtual environment, virtual geographic environments, mobile computation and collaboration, role theory, geo-ontology

VGE Lab Blog: Academic News

Wenhang Li finished his doctoral thesis defense successfully on June 10, 2007.

Abstract