Jianhua GONG，Wenhang LI，Yabing LI，Mingxiang HUANG, 2008. Networked Collaborative Virtual Geographic Environments: Design and Implementation. An International Conference on Developments in Visualization and Virtual Environments in Geographic Information Science, 7-8 January 2008, CUHK, HK.

 Networked Collaborative Virtual Geographic Environments: Design and Implementation

 

Jianhua GONG，Wenhang LI，Yabing LI，Mingxiang HUANG

 

State Key Laboratory of Remote Sensing Science

Institute of Remote Sensing Applications

Chinese Academy of Sciences

Datun Road 3,Chaoyang District

Beijing 100101,P.R. China

Phone : +86-10-64849299 (O)

Email: jhgong@irsa.ac.cn

http://www.vgelab.org/

 

Abstract: Collaborative GIS, collaborative geovisualization, and geocollaboration are cutting-edge areas in geographic information science. This paper aims to explore the conceptual and technical framework for establishing a networked collaborative virtual geographic environment (CVGE) in terms of  the hall for workshop of metasynthetic engineering for coping with complex systems and problems, as well as CSCW, mobile network and the Internet enabled virtual environments, and 3-D geographic information representation and analysis. We argue geocollaboration is involved in two major parts: collaborative modes and geo-problem representations. Interaction and dialogue among participants are highlighted in the paper. In view of overall framework of geocollaboration, 5A Model is developed. 5A stands for  Anyone, Anytime, Anywhere, Anything and Association. The flexible 5A model has little restriction to participants, space, time, and the content of geographic issues, and Anyone, Anytime, Anywhere, Anything are tightly associated with each other; Thus, networked CVGE is regarded as an heterogeneous system composed of the Internet and mobile network, and of heterogeneous clients of computers and mobile instruments. A prototype system is designed and developed with VRML, Java SE, Java ME, and Java 3D. Using the prototype system, participants can connect the CVGE via the Internet and mobile phones, and communicate and interact with each other through 3-D avatars, stream media, and text in collaborative space and geographic space, and also on the filed, and implement dialogue，discussion, and voting of different schemes for collaborative decision making.

 

Keywords: Virtual Geographic Environments, Digital Earth, GeoCollaboration, Collaborative Visualization, Mobile Network, the Internet/Intranet, Distributed Virtual Reality, Mobile CSCW

 

1.  Introduction

 

3-D visualization and virtual reality are increasingly important in geographic information Science and play a great role in wide applications of geographic information technology to the public including managers, policy decisions, geo-teachers, children and so on (Benko et a. ,2003; Brodlie et al.,2004; Gong and Lin, 2001; Gore, 1998; MacEachren et al.,2001) . Up to now, Google Earth has been downloaded by about 0.2 billion times, and has widely been used in every daily life by hundreds of thousands of people (Google Earth,2007). On the other hand, in view of the requirement of geocollaboration by a group of users for dealing with complicated geo-problems such as geographic planning of regional sustainable development, impacts of global environment change, and emergence response, more and more efforts are placed on collaborative visualization and collaborative GIS (MacEachren et al.,2004; Gong and Lin, 2006; Wood et al., 1997). By considering the integration of network based 3-D geo-visualization like Google Earth and collaborative visualization, what are the forms of such new systems? In order to deal with open, huge, and very complex systems, Qian and Dai (2007) put forward the concept of hall for workshop of metasynthetic engineering to integrate group human intelligence and networked computing power. Based on the concept of virtual geographic environments(VGE) (Gong and Lin, 2000,2001) and hall for workshop of metasynthetic engineering, and on the geocollaboration and distributed virtual environments technologies (Singhal and Zyda, 1999), this paper addresses the basic conceptual framework of networked collaborative VGE (CVGE), and develops a prototype to illustrate the form and basic functions of the CVGE. 

 

2.  Virtual Geographic Environments and GeoCollaboration

 

2.1 Features of Virtual Geographic Environments

 

A virtual geographic environment (VGE) is defined as a shared virtual space into which digital geographic objects and environments, as well as 3-D avatars, representing users or people in the physical environments, are transplanted. Thus, a VGE has the following characteristics （Figure 1）:

 

1) A 3D, virtual，void space firstly exist. The virtual space has two kinds: one is perceived or imagination space; the other is a mathematical world which may be unlimitedly large containing varied of 3D, digital objects. Therefore, according to a virtual, mathematical world, spaces occupied by digital geo-referenced objects and environments just represent some kinds of geo-spatial spaces. And there may be a number of no geo-spatial referenced spaces.

 

2) Avatars are focused. People are centered in virtual environments, and avatars depict the identities of the online users or observed people in real worlds. Virtual humans in the virtual space are obvious property of VGE.

 

3) A 3D portal for entrance to the virtual space and environments. A 3D portal is also the human-computer 3D graphical interface which give us basic and constant memory of the virtual worlds.

 

 

Figure 1 VGE Fundamental Features

 

2.2 GeoCollaboration

 

Geo-collaboration can be defined as a group of people working together in both the same or different geographical location and time, to accomplish geo-tasks or to solve complex geo-problems. Geo-collaboration is involved in four components: geographic environment, geo-tasks, task-related geo-problems, and multi-participants. Multi-participants mediated by collaborative tools act in unison to accomplish geo-tasks and solve geo-problems contained within a geographic environment. The major differences between geocollaboration and general collaboration are that the former is involved in the context of complicated, multi-scale  geographic spaces and environments. Combined with the VGE system, geocollaboration could be fulfilled through avatars in a networked,3D, and virtual space based on the representation of geographic environments and geo-problems.

 

3.  Framework of  Networked CVGE

 

1） Current 3-D Virtual Worlds

 

Google Earth and Second Life are currently well-known 3-D virtual worlds on the Internet (Google Earth,2007; Second Life,2007) (Figure 2). Google Earth is representation and visualization of the real physical Earth mainly via multi-resolution remotely sensed images. Second Life is a 3D virtual community within which thousands of virtual humans live and work. The major differences between them are that in the Google digital earth no people live in the virtual landscape which simulate the real geographic environments, while in the Second Life world lots of avatar based people live in the virtual scenes which may have no relation with the physical world. Considering the properties of both simulation of physical worlds and humans, VGE should be designed through the integration of two typical virtual worlds like Google Earth and Second Life.

 

Figure 2 Google Earth and Second Life

 

2） Mobile Communication and Mobile CSCW

 

In recent years, mobile communication technology has been growing rapidly and mobile instruments play a more important role in human daily life. Mobile CSCW is one new research area employing Computer Supported Cooperative Work (CSCW) to explore working mode on mobile devices. Moreover, with the development of 3-D rendering on mobile instruments, many research works have been made on 3-D visualization . Web3D 2006 Symposium showed four 3-D browsers running on mobile PDA devices (Nadalutti et al, 2006). Therefore, supporting “Working Anytime and Anywhere (WATAW)”, networked CVGE should include geo-collaboration among users on the Internet and mobile network.

 

3） Conceptual Framework

 

There is an ideal mode “4A” for pursuing life-time distance learning, which is that anyone can learn anything in an anytime/anywhere environment (Bouras et a., 2001). In the paper, the “5A” model is proposed for geographical researches from view of group collaboration. “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.

 

Based on the VGE concept and “5A” mode, and considering the virtual worlds like Google Earth and Second Life, as well as mobile CSCW, the framework of networked CVGE is established (Figure 3). There are three components: virtual geographic landscapes, virtual consulting studio, and field studio.

Figure 3 Framework of Networked VGE

 

Virtual geographic landscape are representation and visual simulation of global and local geographic environments on the Earth. Spaces in VGE are geospatial and geo-referenced ones that have geographic coordinate systems. Users can navigate in these virtual geospatial spaces and implement communications and interactions between each other. Multi-users can either utilize 3-D avatar or other medium such as ID and name for collaboration. If 3-D avatar is used for user’s ID in virtual space, and the avatar size and location should be consistent with the geo-referenced space. In a VGE, the first things considered are geographic landscape, geospatial relationship and distribution, geo-process, etc., and communications and collaboration among users are in the second place.

 

Virtual consulting studio is a 3-D virtual space on the Internet/intranet may bear no relation to geospatial space, and mainly provide a human-scale room for easily providing interaction and collaboration. 3-D avatars combined with video images of users are required for more infective and intensive communication. Specially, a scaled geospatial space could be nested in a virtual consulting studio, which may allow multi-users observe geographic objects, process and events conveniently.

 

Field studio on mobile network enable users to participate collaborative consultation and discussing meeting at any time and any where. Due to the limit capacity of mobile network and handheld devices at present, field collaboration can be carried out in many ways, for instance, 2-D graphics, 3-D graphics, and stream media images. Data size and transferring, system functions, and visualization modes are needed for specific design for infective communications across the network.

 

In a networked CVGE, avatars are very important. They can appear in virtual geographic environments, virtual consulting studio and even 3-D mobile virtual spaces. Avatars can be depicted by text name , 2-D symbols, 3-D graphics, video-image, and audio-image. Avatars sometimes represent users, sometimes people in physical worlds. They are spirits of the networked CVGE.

 

 

4.  Key Issues of CVGE

 

To date, there are no implementation systems related to networked CVGE. Plenty of  issues are required to coped with for realizing an Internet/Intranet and mobile network based CVGE. From technological standpoints, key issues are as follows.

 

1) Handling of  heterogeneous and asymmetry environments. A CVGE is positioned as an heterogeneous system, composed of heterogeneous networks of Internet/Intranet and mobile network, of heterogeneous clients of computers and mobile instruments. Typical asymmetries of communication capability , computation power, storage capacity, display capability, and so on should be dealt with for implementing networked CVGE.

 

2) Representation of large, multi-scale geographic environments and processes on the network. It is still a challenge for a CVGE system capable of coping with network based 3-D browsing and editing of geographic environment ranging from the global earth to a local, small city, as well as intensive geospatial model computation, model process steering and interactive visualization at varied levels. 

 

3) Technical challenges in collaborative processes among online users. As to the group communication and interaction, research efforts should be placed on multi-perceptive group interactions, data organization and transferring, cooperative process sharing, scene consistency maintenance, long-time connection maintenance mechanism for mobile instruments, etc.

 

5.  A Prototype System

 

5.1 Architecture of Networked CVGE

A Client/Server architecture of a networked CVGS system is designed (Figure 4). On the server side, PC server and Mobile server services are built in terms of  heterogeneous collaborative clients and communication network. PC server service is a multi-thread Java ServerSocket executed in Tomcat Container serving for computer terminals on the Internet or Intranet, and Mobile Server Service is multi-thread Java Servlet using HTTP as protocols serving for wireless terminals such as mobile phone and PDA (Personal Digital Assistant). There are message bridges between PC Server and Mobile Server for collaboration message exchange, thus the collaboration messages can be dispatched among computers and wireless terminals.

 

Operations at computer or wireless terminal (termed as “sender”) will be captured and packaged descriptions as actions with their parameters, which are collaboration messages. These collaboration messages will be sent to the server first and transferred to all other terminals. When a terminal (termed as “receiver”) gets the message, the packaged message will be recognized and decoded to be an actual operation same to the sender according to the operation and its parameters. Collaborations are thus implemented and such descriptions with actions and their parameters are called “Collaboration Protocols”. Sampled protocols are listed in table 1.

 

Table 1 Sampled Protocols in CVGE

	Action	Parameters
	JOIN	User Name			Avatar Figure		Avatar Location
	ADDAVATAR	User ID	User Name			Avatar Figure		Avatar Location
	MOVEAVATAR	User ID	User Name			New Avatar Location
	DELETE AVATAR	User ID
	TALK	User ID		User Name		Message Content
	READVIDEO	nLength		Byte  VideoContent
	READPIC	nLength		Byte  PicContent
	READTEXT	String  TextContent
	SENDPIC	nLength		Byte  PicContent
	SENDTEXT	String TextContent

According to the conceptual framework, the client architecture of a networked CVGE system is composed of three major components: global/local virtual geographic landscapes, virtual consulting studio, and field studio.

Figure 4  Architecture of Networked CVGE

 

 

5.2  A  Prototype  System of  Networked CVGE

 

VRML, Java SE, Java ME, and Java 3D are used for developing the prototype system of networked CVGE. Virtual consulting studio and field studio are focused in the paper. Figure 5 shows the client register interface for PC and mobile participants of the CVGE system. Figure 6 demonstrates 3D virtual consulting studio with a 3D avatar combined with a real-time video image and scene collaborative on mobile phone. In Figure 6, major objects in the virtual consulting studio are avatars, 3-D digital sand-table for placing studied object-virtual geographic environments, a whiteboard for displaying and editing, and a text box for online user talking. Considering limit capacity of mobile device, a stream image based approach is employed to implement geocollaboration on the mobile client.    

  

Figure 5  Register Interface for PC and mobile Participants

 

Scene Collaboration

Text Dialogue for Multiusers

3D Digital Sand table for Displaying Landscape Information

Whiteboard for Displaying Information

   

Figure 6  Interfaces for PC and mobile clients

 

5.3  Functions of the Prototype System

  

DEM of a small watershed on the digital sand-table is modeled in VRML, and users can either observe the 3D landforms of the watershed or, as participants, navigate in the 3-D watershed space embodied by small avatars in an immersive way. This function is involved in the change of users’ spatial reference system. The prototype also can implement state based and process based record and playback of  contents added by users or produced by the consulting process. Meantime, the system can help finish choices of several schemes via anonymous voting. Figure 7 describes the voting process. Firstly, chairman of the meeting announces beginning of voting and the number of schemes to be selected as shown in Figure 7-A. The online client users on PC network and mobile network all receive messages from the chairman, and will be asked to make choices (Figure 7-B, Figure 7C). Figure 8 demonstrates the statistical results of voting displayed on the online user terminals at the same time.        

 

Voting Results

Figure 8  Voting Result after Statistical Computation

 

6. Conclusions

 

Distributed virtual environments and CSCW are the main driven forces for the development of collaborative VGE. The digital earth like Google Earth and Virtual Earth also has a great impact on the 3D,Internet-based visualization of the global and local geographic environments. Goodchild (2008) argues the digital earth could be taken as the great challenge of geographic information science. From the characteristics of virtual reality, geo-collaboration, and mobile CSCW, the paper aims to give the future architecture and  3D portal forms of collaborative geospatial visualization and virtual reality. The CVGE framework, including virtual geographic landscapes, virtual consulting studio, and field studio, on the Internet and mobile network is presented. The paper addresses key issues and fundamental architecture of networked CVGE, and a prototype system is successfully developed for testing the feasibility of major techniques regarding network communication, network based data organization and transferring, 3-D visualization of virtual consulting studio and DEM, realtime video image based avatars, interaction between online PC users and mobile users, collaboration process and so on. As a rudimental work, further research efforts should be directed towards the building of global and local virtual geographic landscapes based on the digital earth technologies, and whole integration of  virtual consulting studio and field studio, and efficiency and stabilities of the CVGE system through more applications.                

 

Acknowledgement

 

This research is partially supported by the National High-tech R&D Program (863 Program) No. 2006AA12Z204, the Key Innovative Project of  the Chinese Academy of  Sciences No. Kzcx2-yw-126-01, and the National Natural Science Foundation Project No. 40471103.

References

l          H. Benko, E. Ishak, and S. Feiner , “Collaborative Visualization of an Archaeological Excavation”. NSF Lake Tahoe Workshop on Collaborative Virtual Reality and Visualization ( CVRV 2003), October 26-28,2003. http://www1.cs.columbia.edu/graphics/projects/ArcheoVis/

l          K.W Brodlie., et al. , “Distributed and Collaborative Visualization”, Computer Graphics Forum, vol. 23, no. 2, 2004, pp. 223-251.

l          C. Bouras and A Philopoulos., Th.Tsiatsos, “E-Learning through distributed virtual environments”, Journal of Network and Computer Applications (2001) 24, 175-199.

l          J.H. GONG, and H. LIN, “A Collaborative VGE: Design and Development”, A Chapter to a book entitled "Collaborative Geographic Information Systems"edited by Shivanand Balram and Suzana Dragicevic, Simon Fraser University, Canada,186-206,2006.

l          J.H. Gong， H. Lin, , “Virtual Geographical Environments and Virtual Geography”, In: Forer P, Yeh A G O, He J, eds. Proceedings 9th International Symposium on Spatial Data Handling, Beijing, China, 10-12 August 2000. 28～39.

l          J.H. GONG, H. LIN, “Virtual Geographic Environments: A Geographic Perspective on Online virtual reality”, Beijing: High Education Press. ( In Chinese)

l          M.F. Goodchild, “Geographic information science: the grand challenges”, In J.P. Wilson and A.S. Fotheringham, editors, The Handbook of Geographic Information Science. Malden, MA: Blackwell, pp. 596–608. http://www.geog.ucsb.edu/~good/,2008 (in press)

l          Google Earth, http://earth.google.com/, 2007.

l          A . Gore， “The Digital Earth: Understanding our planet in the 21st Century”，  given at the California Science Center，Los Angeles，California，on January 31，1998，http://www.digitalearth.gov/VP19980131.html.

l          H. Lin and J.H. Gong, “ Distributed Virtual Environments for Managing Country Parks in Hong Kong -A Case Study of the Shing Mun Country Park”, Photogrammetric Engineering & Remote Sensing. Vol. 68, No. 4, 369-377,2006.

l          A. M. MacEachren, R. Edsall, D. Haug, R. Baxter, G. Otto, R. Masters, S. Fuhrmann, & L Qian, “Virtual environments for geographic visualization: Potential and challenges”, Proceedings of the ACM Workshop on New Paradigms in Information Visualization and Manipulation, Kansas City, KS, Nov. 6, 1999, pp. 35-40.

l          A. M. MacEachren, I. Brewer, “Developing a conceptual framework for visually-enabled geocollaboration”, International Journal of Geographical Information Science. 34(1): 1 – 34, 2004.

l          D. Nadalutti, L  Chittaro., F. Buttussi, “Rendering of X3D Content on Mobile Devices with OpenGL ES”, Proceedings of Web3D 2006: 11th International Conference on 3D Web Technology, ACM Press, New York, April 2006, pp. 19-26.

l          S.S. Qian and L.W. Dai, “On Great Wisdom of Information Space- Fusion of Thinking Science、Literature Art, and Information Network”, Shanghai: Press of Shanghai Jiaotong University, 2007. (in Chinese)

l          Second Life, 2007,  http://secondlife.com

l          S. Singhal and M. Zyda, “Networked Virtual Environments: Design and Implementation”, ACM Press, SIGGRAPH Series, New York, pp. 1-17,1999.

l          J. Wood, H. Wright, K. Brodlie, “Collaborative visualization”, Proceedings, IEEE Information Visualization’97, Pheoniz, Oct. 19-24,1997, pp. 253-259.

 

PDF

转载本文请联系原作者获取授权，同时请注明本文来自龚建华科学网博客。
链接地址：https://blog.sciencenet.cn/blog-113556-51203.html


下一篇：Exploring Human-Oriented Geovisualization, GONG Jianhua, 2008,