Proceedings SLACTIONS2010 International Conference

SLACTIONS 2010 INTERNATIONAL CONFERENCE, Manchester Business School, Second Life, 2010 SLACTIONS 2010 International Conference: Life, imagination, and work using metaverse platforms: Proceedings of the... / edited by Kathy Keeling, Debbie Keeling, Ana Margarida Maia, Ricardo Nunes, Gonalo Cruz and Vnicius Loureiro Manchester, UK: Manchester Business School, 2010. ISBN: 978-0-903808-07-1

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Proceedings of the SLACTIONS 2010 International Conference Life, imagination, and work using metaverse platforms November 18th & 19th, 2010 Manchester Business School Edited by: Kathleen Keeling, (Manchester Business School, University of Manchester, UK) Debbie Keeling, (Manchester Business School, University of Manchester, UK) Ana Margarida Maia (University of Trs-os-Montes e Alto Douro, Vila Real, Portugal) Ricardo Nunes (University of Trs-os-Montes e Alto Douro, Vila Real, Portugal) Gonalo Cruz (University of Trs-os-Montes e Alto Douro, Vila Real, Portugal) Vnicius Loureiro (University of Trs-os-Montes e Alto Douro, Vila Real, Portugal) Local chapters at: Manchester Business School, University of Manchester, UK (chair: Kathleen Keeling) So Paulo, Pontifcia Universidade Catlica de So Paulo, Brazil (chair: Donizetti Louro) Hong Kong, The Hong Kong Polytechnic University, China (chair: David Herold) Houston, Texas Southern University, USA (chair: Ana Boa-Ventura) Tel-Aviv, Tel Aviv-Yaffo Academic College, Israel (chair: Hanan Gazit) Porto, University of Porto, Portugal (chair: Antnio Coelho) Wellington Institute of Technology, New Zealand (chair: Todd Cochrane) Thanks to: SPCVideojogos Sociedade Portuguesa de Cincias dos Videojogos, Portugal Published by: Manchester Business School, University of Manchester, UK, 2010 II

Contents Conference format .......................................................................................................................................................................................................IV The Papers .........................................................................................................................................................................................................................V Virtual societies, virtual economies: An analysis of Second Lifes economic development .............................................................1 Procedural Modeling for Realistic Virtual Worlds Development ...........................................................................................................8 A Proposal for the Development of Behavior of Autonomous Entities in Second Life .....................................................................16 Probing Cognitive Biases in Virtual Worlds: Second Life As a Case Study ..........................................................................................24 Second Life, Second Morality? ........................................................................................................................................................................29 Self-Esteem in Second Life: An inWorld Group Intervention for Women with Disabilities ............................................................34 Using Second Life as an Interface for Personalized Search .....................................................................................................................39 The P.R.O.S.E. (Psychological Research on Synthetic Environments) Project: Conducting In-World Behavioral Research on the Metaverse ......................................................................................................................................................................................................43 Second Life as a research environment: Avatar-to-Avatar interviews. ................................................................................................51 User Involvement in the Design of Educational Virtual Worlds .............................................................................................................54 Affordances for Childrens Participation in Virtual Worlds .....................................................................................................................58 The importance of using devices designed for achieving specific objectives in Virtual Worlds. Exemplification by introducing tools which can be applied for improving three issues involved in the teaching/learning process of a language. ................... 62 Students attitudes and experience: A case of SecondLife ........................................................................................................................67 Using games to promote student integration in universities through the use of virtual worlds ..................75 Puzzles as a creative form of play in metaverse .........................................................................................................................................79 Design Education Towards the Second Life Platform ...............................................................................................................................87 The Literary Theory applied to Creation Process of Second Life residents: A Case Study of Liberato Lindman resident and its development. .......................................................................................................................................................................................................93 Networked Education: The importance of testing the pedagogical design in teacher training in virtual worlds .....................102 Alternate Futures: Afrofuturist Multiverses & Beyond ...........................................................................................................................110 Journalism in Virtual Worlds ............................................................................................................................................................................... 116 MKAC, Museum Kadura Art Center Project................................................................................................................................................122 I Summit Latin American Art.....................................................................................................................127 HELPMI - A virtual helpdesk for virtual worlds and beyond ..133

Committees.........................................................................................................................................................................................................................VI

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Conference format by Leonel Morgado, Nelson Zagalo, and Ana Boa-Ventura

SLACTIONS 2009 was an innovative conference. It was held in the Second Life virtual world, but also in physical (real-life) auditoria over 4 continents. It was a mixed event, with diverse modes of participation and involving several communication flows all the way from those taking place between participants sitting side-by-side at a real auditorium in real life, to those between audience and speakers in a real or virtual podium, or to the communication between participants attending the conference from the comfort of their offices or homes. When we set out to organize an international conference on scientific research involving the use of virtual worlds or metaverse platforms, as this expression renders the concept more precise our first idea was to hold it traditionally, in a Portuguese academic setting. But why make it so local? Why should we drop a rich online environment where we cooperate with colleagues and partners across the world for one where most people would have to allocate significant budget for participation? We decided to organize it in Second Life. We were now left with the problems of the much needed interaction during any conference - what about the informal moments of physical proximity, of eye contact, of physical handshakes, and those healthy discussions while sipping coffee or a hearty tea? What about coffee breaks, conference dinners, evening tours, social moments where one can relax and get a more humane feeling of where fellow participants stand on the topic at hand? Sometimes conferences end up being the single moment in a given year where colleagues who cooperate remotely have a chance to meet. Wouldnt we be missing that? To solve this dilemma, we devised the SLACTIONS format as we describe next. The conference would be held on a single location in Second Life. From here on we will call this the in- world chapter. Participants and speakers would be able to attend and present their papers from physical rooms across the world. From here on we will call these locations our local chapters. Presentations taking place in the in-world chapter would be projected on screens at the local chapters, so people could follow the presentations, and still interact with fellow participants attending the same physical location. And why not let participants at local chapters follow the proceedings with their own computers? Well, they could! But by following a projection, we ensured that a camera operator kept the video flowing from presenter to slideshow to audience, and people could follow proceedings even if they were not acquainted with the Second Life interface. Furthermore, by having less people online, the conference could be enjoyed by many more people than the small crowds typical of Second Life events given the limits imposed by the very technological platform, and local chapters could be held even if their bandwidth allowed only a handful of Second Life avatars.

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The papers

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Proceedings of the SLACTIONS 2010 International Conference Life, imagination, and work using metaverse platforms

Virtual societies, virtual economies: An analysis of Second Lifes economic developmentCtia FerreiraCECC/UCP, Palma de Cima, 1649-023 Lisboa. E-mail: [email protected] internet growth a new dimension for our social lives is emerging, a virtual one. Within this virtual dimension we are able to have several activities, from sending electronic mails, to operating a transaction through our web-bank, managing a blog, or even being a character in a game or non game-based virtual world. Within these virtual spaces several communities are rising and in some cases we may even be witnessing the rise of new virtual societies. In order to achieve a better understanding on the emergence of these new types of societies our proposal is to analyze one of the most important residential virtual spaces Second Life. The central element of our analysis will be its economic system. Online multiplayer games are one of the most used web-based platforms. Through these virtual spaces we can achieve an alternative space for the development of our social lives, a sphere characterized by de-materialization of social interaction: the growth of the internet, and of shared virtual reality spaces within it, has enabled new choices in terms of what kind of physical beings we inhabit. (Castronova, 2003: 7). Second Life is one of the most complex virtual worlds available. In this platform players are invited to actively participate in its development, not only in space construction buildings, green spaces and general surroundings, but also in its social development institutions and groups that will contribute to in-worlds economy, culture, identity or hierarchical organization. Second Life has reached such a development level that nowadays it is possible to do almost everything that we can do in real life: going for a walk in several touristic locations, practice sports, play games, go to the theatre, cinema or a concert, attend conferences or classes, talk with friends or meet new people, meandering throughout the world, or even to have a job. One of the characteristics that make this virtual world different from the other is its economic system. The majority of massive multiplayer online role-playing games have economic systems you need to have money (usually designated by gold) to be able to buy artifacts that empower your avatar. What makes Second Life different is not the fact that it has its own economic system or even its own currency, but the possibility of exchanging its virtual money for real one 1 and vice versa . This distinguishing feature is making its economy almost as complex as the real one. This paper aims to analyze Second Lifes economic development in order to verify if we may be witnessing the emergence of new moneyscape and consequently an alternative social dimension. Our analysis will be draw upon statistical data released by Linden Lab.

Second Life is one of the most popular virtual worlds. It offers almost endless possibilities depending on what we want to do: we may just wander from place to place, explore the several locations that constitute this world or we can accomplish specific activities like going to a concert or to a conference, or even having a job. The characteristic that make this virtual world different from the others is its economic system. The majority of the massive multiplayer online role-playing games have an economic system we need to have money (usually gold) in order to be able to buy artifacts that empower our avatar. What makes the Second Life different is not the fact that it has an economic system or its own currency, but the possibility of exchanging its virtual money for real money. This possibility makes its economy almost as complex as the real one. Our proposal is to analyze Second Lifes economic development in order to verify if we may be witnessing the emergence of new moneyscape and consequently an alternative social dimension. Our analysis will be draw upon statistical data released by Linden Lab.

IntroductionThe modern consumer society turned the spending of money not only into a central economic practice, but into a dynamic, complex cultural and social activity. (V. Zelizer, 1997: 2001)

Money is a central element in contemporary societies. In The Philosophy of money (1982), Georg Simmel

conceptualized money as a symbol and analyzed its effects upon people and society. As soon as symbolic exchanges were replaced by the use of money we observed the rising of a new form of social interaction the economic exchange (cf. Simmel, 1982). Social development has been shaped by the element money once with money in our pocket, we are free [] (Simmel, 1991: 23). Money became one of the most prominent elements of modern societies, but regardless the social evolution of our era an era characterized by the massification of new communication technologies, OECD considers that the three classic functions of money are not expected to change in near future. It is expected the rise of new digital forms of payment that make economy more and more global, nevertheless, money will continue to be an unity of account, mean of payment, and store of value (cf. Miller et al, 2002). Despite the fact that money will be keeping its primary characteristics, we are witnessing a change, a change in the social dimension where transactions take place. With

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Virtual lives, virtual economiesBefore the advent of the avatar, there was only one world to live in, Earth, and only one avatar to inhabit there, the Earthly body. The recent emergence of virtual worlds besides Earth has vastly expanded the range of choices regarding ones own physical being and the space which it inhabits. (Castronova, 2003: 32) Internet development and generalized use were very important to bring reality near fictions technological worlds that are a recurrent theme in literature and cinema th 2 since the beginning of 20 century . With internet development and the rise of web 2.0, or social web, we are witnessing the growth of social platforms. In the last years several social applications rose; the goal of all of them is to induce interaction, collaboration and share among their users. Blogs, podcasts, wikis, social and sharing networks and social games are among the most popular web 2.0 applications (cf. Pascu, 2008). Social games, one of the characteristic applications of web 2.0, are a sub-genre of massive multiplayer online games. These games revolutionized not only video-games industry but entertainment industry in general. The first online multiplayer games were remarkable, they allowed players from all over the world to get together and play in a shared space. The virtualization of social space had a notorious impact in entertainment industry and the number of networked players grew rapidly. However, the goal of these games was similar to the majority of games to win, to be the most powerful and eventually the most feared. The distinctiveness of massive multiplayer online social games is their aim: to live. The challenge is not to be the first to achieve the end and to win the game, but to live an 3 experience through an avatar , a character created to live in this alternative space. This kind of games may take place in varied settings and offer different possibilities but there is a common element they recreate new worlds, new social spaces, second lives. One of the examples of these technologies is a virtual space created to offer the possibility of living in a different dimension, a different reality that have several similarities to the real one Second Life. This platform like other virtual worlds is often called metaverse, meaning a virtual world where humans represented by avatars interact in a tridimensional digital space. Virtual spaces like Second Life offer the possibility of having a virtual representation on a different dimension the cyberspace. Through these web-based platforms we can achieve an alternative sphere for the development of our social lives, a sphere characterized by de-materialization or de-physicalization of social interaction (cf. Knights et al, 2007: 750). The first large scale multiplayer 3D environments appeared in the 1970s, but as soon as internet was made available for personal computers the number of these platforms rapidly increased. Nowadays there are more than 50 3D virtual environments; one of the types of these virtual spaces is what Edward Castronova called synthetic worlds worlds that are created completely by design and

live only within computers are synthetic, and the world of earth, air, fire, water and blood that weve inherited from our forebears is real.(Castronova, 2007: 7). Second Life is one of the most complex synthetic worlds available, in this platform players are called residents and they may actively participate in worlds development your world, your 4 imagination . Residents are represented by avatars, humanoid figures that might be totally personalized and even lose their original human look. It is through these avatars that residents develop an active and complex social network: The avatar mediates our self in the virtual world: we inhabit it, we drive it, we receive all of our sensory information about the world from its standpoint. (Castronova, 2003: 5). Avatars are the medium that allow us to have a virtual representation. Second Lifes development level improved so much since its launch in 2003 that now it is possible to do almost everything that we can do in real life, and residents are more and more exploring the several possibilities offered by this platform, at the same time they are organizing themselves in thematic groups and communities. The growth of residents interest in in-worlds activities had encouraged Second Lifes economic development; but this interest was also promoted by Second Lifes intellectual property rules, which define that everybody has the intellectual property of what they create, so they may sell it to other residents if they want. This innovative right helped to stimulate in-worlds economy and residents begin to invest time and money in this virtual place. Linden Labs business model is then based on the premise: you pay for the land, so you may build whatever you want, and you may charge visitors for activities or products, and at the end you can take the earned Linden Dollars and change them for real money. The possibility of exchange Linden Dollars for a palpable currency is one of the characteristics that made Second Lifes economic activity so prominent nearly 5 USD$35 million are traded monthly between residents . This volume of transactions makes Second Life one of the world's largest user-generated virtual economies.

Second Life: the emergence of a new moneyscapeNowadays Second Life is not the same platform that was launched in June 2003 by Linden Lab. It evolved and became an alternative social dimension. Through its development it passed through key milestones that had direct impact in its social structure. Three of these keymoments were LindeXs creation in 2006, gambling prohibition in 2007 and Xstreet acquisition in 2009.

LindeX, gambling prohibition, XsreetLindeX is Linden Labs own currency exchange; through this service we are able to buy and sell Linden Dollars. It is available for residents in Second Lifes website or in 6 several places in-world . This service offered by Linden Lab allows them to control in-worlds micro-currency value, and since its launch Linden Dollar has been a stable currency. Gambling prohibition also contributed to a better

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control over Linden Dollar. Until 2007 gambling was legal in Second Life, this activity had a very important role in inworlds economy and everyday millions of Linden Dollars were transacted through this industry; but following the US gambling law Linden Lab had forbidden all type of gambling games:While Linden Lab does not offer an online gambling service, Linden Lab and Second Life Residents must comply with state and federal laws applicable to regulated online gambling, even when both operators and players of the games reside outside of the US. And, because there are a variety of conflicting gambling regulations around the world we have chosen to restrict gambling in Second Life as described in a revised policy which is posted in 7 the Knowledge Base under Policy Regarding Wagering in Second Life.8

After this change economy development decreased, but just a few months later economic flows recovered the previous levels residents began to invest in land and traditional economic activity began to gain importance in this virtual space. By this time the almost infinite capacity of creation offered by Second Life began to be finally explored by residents. Nowadays there are some very lucrative activities that take place within this virtual world; one of these is the creation of objects and scripts that enriches the virtual experience. Commerce became such a major activity that in the beginning of 2009 Linden Lab bought one of the most important shopping web sites of Second Lifes products, 9 Xstreet . This acquisition made commercial transactions among residents much easier.

Economic stability and the emergence of a new moneyscapeThroughout Second Lifes development Linden Lab made the effort to present its synthetic world as an appellative one in order to compete for audiences with game worlds as World of Warcraft or EverQuest. One of Second Lifes major strengths has been its economical solidity.

Throughout the years and because of the adjustments described Linden Dollar stabilized and began to be seen as the official in-world currency. Users established a stable relationship with it and it is the monetary unit used for all kind of transactions within Second Life. Since LindeXs creation Linden Lab is being able to guarantee its stability and Linden Dollars exchange value has remained stable since then approximately L$250 to the US Dollar. This stability was understood as an invitation to investment and residents are transforming the possibility of having a second life in a virtual representation of the real one while in-world they are in a synthetic world but have a real economic behavior (cf. Castronova, 2006). In order to understand the new cultural global economy Arjun Appadurai (1996) suggests an alternative model, a model that explores the relationship between the scapes of contemporary cultural global flows: ethnoscapes, mediascapes, technoscapes, financescapes and ideoscapes. The suffix scapes was chosen in order to represent the flows of modern world: ethnoscape the landscape of persons who constitute the shifting world; mediascape the distribution of electronic capabilities to produce and disseminate information as well as the images of the world created by these media; technoscape the global configuration of technology; financescape the landscape of global and fluid capital; and ideoscape a scape marked by the global master-narrative to understand and represent the world (cf. Appadurai: 1996). Having this conceptualization as basis, we want to purpose a new scape, the virtual moneyscape. We understand moneyscapes as being complementary to financescapes. Financescapes are related to a global capital disposition that is a more mysterious, rapid and difficult landscape to follow than ever before. (Appadurai, 1996: 34). By moneyscape we intend the dimension of our lives that is connected to money, either as an economic element, or as a cultural one. Due to its economic development Second Life is becoming a virtual moneyscape within this virtual space money has a major role both as an economic and cultural element. Linden dollars may be understood as the social glue of this virtual environment. The number of hours and amount of money invested in Second Life reflect its social-economic development level. In the second quarter 2006 users spent 10 million hours inworld. This number had increased until the 2nd quarter 2009 and from the 3rd it decreased from 126 to 109 million nd hours in the 2 quarter 2010 (see Chart 1):

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Chart 1 Hours spent in-world (2006-2010) 140.000.000 120.000.000 100.000.000 80.000.000 60.000.000 40.000.000 20.000.000 0

Chart 2 Average no. users with repeat logins (2006-2010) 900.000 800.000 700.000 600.000 500.000 400.000 300.000 200.000 100.000 0

During the two final quarters 2006 the number of users with repeated logins was around 487 thousand, and in the two first quarters 2010 this number increased to approximately 1.4 million (see Chart 2):

If we compare the two final quarters of 2006 with the two first quarters 2010 we see that the number of transactions among users increased from 53 million to 186 million. Chart 3 represents these transactions by amount:Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q

Chart 3 Transactions among users by amount (2006-2010) 120.000.000 100.000.000 80.000.000 60.000.000 40.000.000 20.000.000 0 2006 2006 2006 2007 2007 2007 2007 2008 2008 2008 2008 2009 2009 2009 2009 2010 2010 2nd >= 500,000 L$ 100,000 - 499,999 L$ 20,000 - 99,999 L$ 5,000 - 19,999 L$ 1,000 - 4,999 L$ 500 - 999 L$ 200 - 499 L$ 50 - 199 L$ 20 - 49 L$ 2 - 19 L$ 1L$

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Chart 4 Volume of $US exchanged through LindeX (2006-2010) 35.000.000 30.000.000 25.000.000 20.000.000 15.000.000 10.000.000 5.000.000 0

Chart 5 Volume of Xstreet sales (Linden Dollars) (20062009) 1.000.000.000 800.000.000 600.000.000 400.000.000 200.000.000 0

The majority of transactions among users entail low values to around 1.4 billion Linden dollars till L$19. Nevertheless throughout the years the number of transactions between L$20.000 and over L$500.000 have been increasing. In the same period of time final two quarters 2006 and first two quarters 2010 the amount of virtual currency exchanged in LindeX increased from US$14 million to US$60 million (see Chart 4); and the Xstreet sales increased from L$99 million (when it didnt belong to Linden Lab)(see chart 5). Regarding the profit obtained in-world, the number of in-world business owners with profit is increasing, as well as the profit by amount. In the last two quarters 2006 the profit distribution per business owners was: less than $10US 36.606 (total users with profits from in-world businesses); $10-50US 19.119; $50-100US 5.186; $100-200US 3.975; $200-500US 3.475; $500-1.000US 1.510; $1.000-2.000US 911; $2.000-5.000US 543; and more than $5.000US 295. The profit distribution by amount in the first two quarters 2010 was: less than $10US 234.051 (total users with profits from in-world businesses); $10-50US 113.878; $50-100US 23.464; $100-200US 16.107; $200-500US 15.194; $5001.000US 6.396; $1.000-2.000US 3.702; $2.0005.000US 2.329; and more than $5.000US 1.264 (see Chart 6). This data shows how profitable Second Life can be and why the in-world investment is still growing.

Chart 6 Business owners profit by amount (2006-2010) 250.000 200.000 150.000 100.000Q Q Q Q Q Q Q

> $5000 USD Profit $2000 to $5000 USD Profit $1000 to $2000 USD Profit $500 to $1000 USD Profit $200 to $500 USD Profit $100 to $200 USD Profit $50 to $100 USD ProfitQ Q Q Q

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The investment in virtual land, on the other hand, has not been so stable. The land auctions are exclusively conducted by Linden Lab and in those the area available to auction is not always the same. As the acres auctioned decrease (see Chart 7) the land sales among residents increase (see Chart 8), which means that land is also a profitable business for residents. In spite of being lucrative to residents, it is also good for Linden Lab because to be able to buy land residents must upgrade their accounts to paid ones known as Premium accounts. Chart 7 Acres auctioned 80.000.000 70.000.000 60.000.000 50.000.000 40.000.000 30.000.000 20.000.000 10.000.000 0

Lifes economy is stable by the end of 2009 it was evaluated in 500 million Euros. If we compare it, for instance, with facebook, this social networks economy is not close Second Lifes development level; but on the other hand, facebooks user number is increasing rapidly and it has already exceeded 500 million users. Even though Second Lifes economy had stabilized, the volume of inworld transactions remains stable; in fact Second Life is being seen more and more as an alternative space to the development of economic activities, once it has not real life 10 contingencies and offers a new set of possibilities . Reallife companies are still investing in this virtual world; last month there were 378 companies registered in Second Life.

ConclusionSecond Lifes prominent economic development is having consequences in economy at two levels: in-world and outworld, meaning Second Life and first life economies, respectively. At the level of in-world economy we are observing an increase of monetary investment, residents are exchanging more real money for virtual one and this is stimulating transactions among them. On the other hand at the level of out-world economy, residents are exchanging more Linden dollars for currencies that have a real market value. This means that there is a higher volume of virtual produced money entering real life economy. Regarding this, it is important to understand the impact that this new economic dimension may have. The economic capital produced inside virtual worlds is the result of the emergence of an alternative social dimension; people are cultivating new and existing social networks in cyberspace which is leading to the rise of a new social-economic dimension constituted in a virtual scape. Second Lifes importance as a new moneyscape is growing and despite the world economical crisis residents and first life companies continue to invest in-world and to exchange high amounts of real currencies for Linden dollars. We may understand this phenomenon as the growth of a parallel economic dimension which has its own microcurrency and consequently its own economic and social system. 11 Despite the level of uncertainty that still is associated to virtual worlds, Second Lifes economical data shows that the level of trust in this alternative dimension is growing, so this platform may not be the future of virtual moneyscapes but it helps us to understand what might be the future of world economy and of the cultural life of dematerialized money which share its main characteristic with real currencies: it is a unity of account, mean of payment and store of value. REFERENCESAppadurai, A. (1996). Modernity at large: cultural dimensions of globalization. Minneapolis: University of Minnesota Press.

Chart 8 Land sales by residents (square meters) 450.000.000 400.000.000 350.000.000 300.000.000 250.000.000 200.000.000 150.000.000 100.000.000 50.000.000 0

These statistical data show that Second Life is still growing but in a much slower rhythm than it did between 2006 and 2007. We consider that there are two main influences for this slow down: 2008 financial crisis that is still affecting world economy, and the growth of social networks, particularly twitter and facebook. Despite this Second

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Proceedings of the SLACTIONS 2010 International Conference Life, imagination, and work using metaverse platforms Castronova, E. (2002). On virtual economies. CESifo Working Paper Series, No. 752. Retrieved 10/06/09 from http://ssrn.com/abstract=338500. Castronova, E. (2003). Theory of the avatar. CESifo Working Paper Series, No. 863. Retrieved 10/06/09 from http://ssrn.com/abstract=385103. Castronova, E. (2006). Synthetic worlds: The business and culture of online games. Chicago: Chicago University Press. Castronova, E. (2007). Exodus to the virtual world: How online fun is changing reality. New York: Palgrave Macmillan.Dibbell, J. (2007). Play money. Or, how I quit my day job and made millions trading virtual loot. New York: Basic Books.

manipulated by a computer user (as in a computer game) (Merriam-Webster Online, retrieved from http://www.merriamwebster.com/). 4 Second Lifes slogan.5

Data retrieved from http://secondlife.com/statistics/economydata.php. Average registered in 2009.6

Knights, D. et al (2007). Electronic Cash and the Virtual Marketplace: Reflections on a Revolution Postponed. Organization 14.6: 747-768. Malaby, T.M. (2006). Parlaying Value: Capital in and beyond Virtual Worlds. Games & Culture 1(2):141-162. Miller, R. et al. (2002). The future of money in OECD (2002). The future of money. Paris: OECD Books. Pascu, C. (2008). An Empirical Analysis of the Creation, Use and Adoption of Social Computing Applications. IPTS Exploratory Research on Social Computing. JRC Scientific and Technical Reports, EUR 23415 EN. Retrieved 28/07/09 from http://ftp.jrc.es/EURdoc/JRC46431.pdf. Simmel, G. (1982). The philosophy of money. Boston: Routledge & Kegan Paul (1978). Simmel, G. (1991). Money in Modern Culture. Theory, Culture & Society 8: 17-31. Zelizer, V.A. (1997). The social meaning of money: pin money, paychecks, poor relief, and other currencies. Princeton: Princeton University Press (1994).

There are Lindex kiosks at several in-world locations, as well as ATM points. Both of them have the same purpose, but configuring them in different formats allows recognizing two different real-life activities money exchange and cashing withdrawals. 7 http://wiki.secondlife.com/wiki/Knowledge_Base 8 Complete announcement available at: https://blogs.secondlife.com/community/features/blog/2007/07/26 /wagering-in-second-life-new-policy 9 https://www.xstreetsl.com/10

There are researches that show how virtual social spaces, especially game-based ones, are being used as an alternative economical spheres (see, for instance, Castronova: 2002, 2006, Dibbell: 2007, Malaby, 2006). 11 This uncertainty is mainly related with the fact that virtual worlds like Second Life are not palpable, and there still is a high number of people that see them as not trustworthy. Not only there is distrust because of anonymity, but also because Linden Lab has control over Second Lifes continuity if Linden Lab decides to shut down the servers this virtual spaces ceases to exist.

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The exchange process is similar to the real value currencies one. Linden Lab has an exchange platform Lindex, where is possible to exchange real currencies for Linden Dollars and vice versa. In the majority of virtual worlds (including immersive multiplayer game environments) the virtual currency is not exchanged but bought as an object; and it is not unusual to find these currencies at sale in platforms like ebay. 2 Science fiction is a genre that had appeared in the 19th century. Science evolution was the main theme of the first sci-fi narratives. 3 The etymology of avatar proceeds from Sanskrit avatrah meaning the descending of a divinity from paradise to Earth. According to Merriam-Webster Online Dictionary the substantive avatar means the incarnation of a Hindu deity (as Vishnu), an incarnation in human form, and an embodiment (as of a concept or philosophy) often in a person. Due to the high number of virtual worlds, the concept avatar acquired a technological significance: an electronic image that represents and is

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Procedural Modeling for Realistic Virtual Worlds DevelopmentPedro Brando SilvaFEUP/DEI, INESC Porto, Rua Dr. Roberto Frias, s/n 4200-465, Porto, Portugal Email: [email protected]

Antnio CoelhoFEUP/DEI, INESC Porto, Rua Dr. Roberto Frias, s/n 4200-465, Porto, Portugal Email: [email protected]

The creation of virtual environments, corresponding to real world settings, constitutes one of the most important, but also most time and resource demanding processes in content development for virtual worlds. By querying real-world data sources, the building process can be automated, reducing the need for human intervention. However, these may present additional management difficulties due to their number, dimension, format or level of detail, therefore requiring specific techniques to operate on them. This paper describes the application of a procedural modeling solution, called PG3D System, on the creation of realistic virtual urban environments and their employ in virtual world applications. This systems implementation in spatial database management systems induces fast data access, large data manipulation features, complex query capabilities and format flexibility, allowing the fast creation of large scale virtual environments, imbued with optimized data structures, compatible with any digital game, custom modeling tool or metaverse platform.

Figure 1: Sydneys representation for Second Life (Linden Research Inc., 2011) The use of procedural methods for generating threedimensional content for virtual reality applications has become a recurring practice, with interesting results, requiring much less effort, by generating, automatically (or at least, with little human interaction) three-dimensional models. Some guidelines and directions should be introduced by the user, or information sources that are used to describe the spaces in detail. However, sometimes the size and number of such sources is too large, thus requiring fast ways to access them and powerful machines to operate on them. On the other hand, this does not necessarily mean that such sources are detailed enough to obtain accurate models, which makes it crucial to use stochastic methods or empirical data on the urban environment to amplify the existing information. To address these issues, the PG3D modeler, a solution for procedural modeling of virtual urban environments, has been conceived. This paper aims to describe the advantageous application of the PG3D modeler in virtual environment creation for virtual worlds. Its main characteristic is its implementation in spatial databases management systems, and operation based on a PG3D Grammar, a set of rules, which defines the instructions for the modeling procedures. To complement the database, a management tool also exists, allowing the configuration of the necessary parameters of the modeling processes, as well as the export

IntroductionThe creation of virtual environments constitutes is one of the most demanding processes regarding the development of virtual reality applications, in the way that it requires the design of large amounts of highly detailed and quality contents. This leads to great costs and a great deal of effort, as well as long development periods. When considering metaverse platforms, where people and organizations try to introduce their real world structures, the recreation of existing urban environments has become a frequent goal. This leads to a greater immersion of the player to the scene when he recognizes it, or to an aspiration to visit the real world structures when he does not. For developers however, this presents greater difficulties, since real information must be used (figure 1).

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of generated data into a set of interoperable formats, inducing its use in various applications, such as digital games, custom modeling tools and metaverse platforms. These two parts together compose the PG3D System.

The PG3D SolutionThe creation of realistic urban environments presents several challenges to which many authors have tried to answer over time. These include, for example, the visual correspondence in real environments, the use of information sources, or even the definition of sufficiently powerful tools able to model large urban areas. The goal of this section is to present how PG3D tries to address them. A more complete description can be found in (Silva, 2010)

Related WorkThis work fits into the scope of procedural urban modeling, a research area which already possesses quite a few number of interesting approaches, some of them dedicated to specific subjects. Regarding the modeling of terrains, there is the work of Bruneton e Neyret (Bruneton & Neyret, 2008), which presents a method to integrate the various components that lie over them, such as streets, rivers and lakes, relying on a view dependent quadtree refinement scheme. For road creation, Parish and Mller used Lindenmayer Systems or L-Systems for short (Prusinkiewicz & Lindenmayer, 1996) - originally used in the simulation of plant and organism community growth, being able to generate extensive street networks(Parish & Mller, 2001). With the same goal in mind, Chen et al. used tensor fields, which allowed interactive control over the road generation (Chen, Esch, Wonka, Mller, & Zhang, 2008). In their CityGen system, Kelly and McCabe (Kelly & McCabe, 2007) introduced a more interactive way to define primary and secondary roads. Regarding the modeling of buildings, Wonka et al. introduced the split grammars (Wonka, Wimmer, Sillion, & Ribarsky, 2003), a new type of parametric set grammar based on the concept of shape brought up by Stiny and Gips(Stiny, 1980; Stiny & Gips, 1972). He also presented an attribute matching system oriented by a control grammar, offering the flexibility required to model buildings with many different styles and designs (Wonka, et al., 2003). Based on this work, Mller et al. developed the CGA Shape (Mller, Wonka, Haegler, Ulmer, & Gool, 2006), a shape grammar capable of producing extensive architectural models with high detail. The CGA Shape is a sequential grammar (such as the Chomsky Grammar(Chomsky, 1956)), therefore all the production rules are applied in sequence, in order to allow the characterization of structure (Mller, et al., 2006). The implementation of the CGA Shape is integrated in the CityEngine framework (Procedural Inc., 2009). Although these approaches are able to produce high quality fictitious urban environments, few are dedicated to the reproduction of real world urban environments, having therefore limited GIS data support. For this matter, Coelho presented in his work (Coelho, Bessa, Sousa, & Ferreira, 2007) the Geospatial L-Systems, an extension of parametric L-Systems which incorporates spatial awareness. This combines the ability of data amplification provided by the L-Systems (whose production rules are applied in parallel) with the geospatial systems, allowing spatial analysis of georeferenced data. This solution is integrated into a modeling tool called XL3D modeler, which provides interoperable access to various sources of information, allowing the reproduction of real urban environments.

The PG3D ModelerThe name PG3D is an acronym for Procedural Generation 3D, but is also related to its implementation process, namely to the technologies in which it was implemented. The fundamental idea behind the PG3D concept is to develop the procedural modeling processes directly on a spatial database management system where either geographic data sources, as well as the created models, are saved. The modeling operations are developed as stored procedures in programming languages of the database itself. The platform that possesses PG3D modeling capabilities is called a PG3D modeler. Since the objective lies on the modeling of real urban environments, the use of real world data is of utmost importance. Once loaded into the database, they can be queried directly without great overhead. Likewise, once started the modeling process, both final and intermediate results will be recorded in the database allowing the execution of more complex queries on them, thus expanding the range of modeling possibilities, as well as guaranteeing the safety of the generated data in case of crash or failure. Also, by relying more on database access, it can operate on smaller sets of data a time, thus overcoming the memory limits that sometimes occur for larger environments.

Use of Spatial DatabasesThe modeling of virtual urban environments replicating real environments leads to the need for data sources which describe the various features that compose them, such as its location, height and appearance. Such information, however, can hardly be found in a single source and organized in one place. It is essential that these sources can be connected somehow by having some common reference. In this sense it is important that the data is georeferenced, i.e. contains a reference of its location on the earth's surface. This spatial information is fundamental to relate the many entities in the multiple sources. While any database is capable of processing alphanumeric data, the spatial databases have additional features for processing spatial data types. These are normally called geometries. The Open Geospatial Consortium (OGC) specification created the "Simple Features", which defines various types of geometry (Open Geospatial Consortium, 2010). Spatial databases are also packed with multiple functions to operate over this type of data, as well as indexing features, which induce optimized search abilities.

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The spatial databases are thus a solution for storage, organization, operation and management of multiple sources of georeferenced data. Given their additional capability of editing and processing of data, format incompatibilities can easily be solved. Moreover, they can provide special features to the PG3D Modeler, since their own modeling processes act on similar data structures and may enjoy from their optimal query and geometry management abilities. data load, to be used in further steps.

PG3D GrammarDerived from its close relationship with the database and its implementation in own programming languages, the PG3D Grammar was born. On the one hand, it defines structures and operations, taking advantage of the PG3D concept, but on the other hand, second, it expands its range of possibilities. As the technical implementation details of this grammar do not constitute the main subject of this article, a more general overview will be presented, whereas a more complete explanation can be found in (Silva, 2010). PG3D grammars are an extension of shape grammars (Stiny, 1980), more specifically, the CGA Shape (Mller, et al., 2006), endowed with the capabilities of geospatial awareness and relational development, stemmed from Geospatial L Systems (Coelho, et al., 2007). Having been strongly influenced by both, it constitutes an attempt, where possible, to combine their greatest potential. Before discussing the structure of the grammars, some of its basic concepts must be explained: PG3DShape: The PG3DShape or shape for short, is the main data structure manipulated by all procedural modeling processes, and therefore also in the PG3D grammar. A shape can correspond to a surface street, building, or even just a portion of it, such as a wall or corner of a window (figure 2). A shape contains a set of geometries that graphically describe the type of element to be represented. The PG3DShape is set in a hierarchy. As will be described later, shapes evolve by successive substitution. It is therefore possible for one to know its predecessor, i.e. the shape from which it derives, allowing querying on shapes that descend from a particular predecessor.

Figure 3: Relationship between multiple layers The geographic references contained in the layers shapes turn their relationship possible, making it possible, such as in the example above, to combine information about the road networks and building bases with surface information, fitting into each other in an appropriate manner.

Grammar DefinitionThe PG3D grammar can then be described by its constitution in the following elements: \endash A set of PG3DShapes, which aggregates one or more elements with graphical representation. \endash The axiom, which defines the starting point of the modeling processes, defined by one or more PG3DLayers. \endash A set of user-defined production rules, called PG3DRules, which delineate the modeling instructions, specifically the processes of replacement and development of PG3DShapes. The procedural modeling process consists in successively replacing shapes in an iterative manner, starting with the axiom, and following the instructions contained in production rules. In the first iteration of the process, the layers that are part of the axiom (which indicate what sources of data should be loaded) are analyzed. After this point, having already a set of shapes, the procedure is developed iteratively - at each iteration, for each shape created, a production rule matching that shape is searched and applied. Once this is done for all shapes, it moves on to the next iteration which will handle the newly created shapes in the previous iteration. This process is repeated until no more rules are applicable to any shape or if an iteration limit, imposed by the user, has been reached. The main idea behind the successive replacement of shapes is of progressive creation of detail, which means the models are incrementally improved. Thus it is possible to generate simple, usable models in a first step, and evolve them according to available data sources and rules. The result of each step can be queried separately, which can be extremely useful in virtual world applications to generate various levels of detail of the same environment.

Figure 2: Various kinds of PG3DShapes PG3DLayer: A layer is a data structure that includes one or more shapes that share the same data source, therefore a common meaning, serving as a way to organize the shapes. A set of PG3DLayers define the starting point for a procedural modeling process, containing instructions on

Production RulesProduction rules are structured in the following form: Predecessor SuccessorIn its most basic form, the definition of the predecessor

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consists of a capitalized symbol composed of alphanumeric characters. This rule shall be applied to all shapes that have a matching symbol. The successor, in turn, can become quite complex, containing a sequence of modeling operations and symbols, which will mark each new shape creation. Each new shape will be the result of applying all previously called operations on the predecessor shape, and will act as its replacement. Consider the following example:

in most cases some prior processing is needed before they can be used. For that, PG3Ds implementation in databases is extremely advantageous, since it can perform many functions (arithmetic, geometry manipulation or modeling) in queries (e.g., SQL or the used language) and therefore create new sources with usable formats. Besides using own PG3D structures, which allow easier data manipulation, a geometry representation of shapes, polygons and vertices are used, namely the multipolygon, polygon and point types (Open Geospatial Consortium Inc., 2006), respectively. Their employ allows direct use of existing geometry manipulation functions as well as optimized indexing, speeding search operations, which are especially important in geospatial awareness features.

Shape1 translate(vector3(0,10,20)) Shape2 scale(vector3(5,5,5)) Shape3 colorShape(rgba(255,0,0,255) Shape4; This rule will replace all shapes called Shape1 by 3 different shapes. Shape2 will correspond to a simple translation of Shape1, Shape3 will be 5-time bigger version of Shape2, and Shape4 will be equal to Shape3, except red colored. The operations are therefore applied in sequence, while the shape naming saves these changes as new shapes, which will replace Shape1. Rule definitions may contain additional features to allow the construction of more complex structures (Silva, 2010). Parametric Rules: From one rule application to the next, it may be necessary to send certain information. For that reason, the production rules do accept parameter definition, in a similar way functions in programming language like C++ do. Conditional Rules: The definition of rule conditions is essential for the development of shapes, especially when loaded with external information sources or when subjected to stochastic processes. The PG3D Grammar thus includes support for control structures, such as the IFTHENELSE expressions. Stochastic Rules: To compensate for the lack of information that some sources may contain, the use of randomness can become a form of data amplification, when used and controlled effectively. The parameterization can be achieved through specific expressions provided which operate based on probabilities, which can control, for instance, the frequency of appearance of a particular characteristic in a certain environment. Parenthetic Rules: By using a stack it is possible to save and load states, i.e. results of transformations over shapes. By using PUSH, the current state is saved on a stack, and loaded from it when POP is used. The use of the name parenthetic derives from its concept from LSystems, which use the [ and ] operators to achieve this goal, but to avoid conflicts with array definitions, it has been replaced in PG3D. Attributes, Limits and Textures: Using the same values in more than one production rule is a common practice. Therefore it is possible to declare constants only once, and use them multiple time in rules.

Conditional and Characteristic DevelopmentOne of the major feature of the PG3D Grammar is its ability to conditionally develop each shape (or any of its parts, namely vertices or polygons) based on its properties. In other words, the evolution of a shape may depend on its current status or on the corresponding data that may exist in the data sources. The control structure IF...THEN...ELSE is one way of checking these properties. The other exists at function level, in that the some support a boolean parameter, allowing the operations to be applied only to parts of a shape fitting a certain condition. To indicate the intent to act based on the state of the shape or its vertices or polygons, PG3D supports the three reference symbols starting by the percentage sign, %s, %p, %v, respectively.

Geospatial AwarenessThe concept of contextualization in geospatial PG3D grammars derived from its application in Geospatial LSystems (Coelho, et al., 2007). Its main idea consists in developing shapes not independently, but based on their surroundings, avoiding the creation of unrealistic structures. This is especially important when performing occlusion tests.

Figure 4: Colored faades demonstrate geospatial awareness Suppose a couple of buildings share common walls: these should not contain any windows, balconies or front doors. Since all the elements are spatially referenced, such check is easily achieved. Figure 4 shows building walls which do not have any other wall in front of them at a distance lesser than 3 meters away. This makes them potential good faades for buildings:

Transforming, Reading and Accessing Real Data and GeometriesThe first step in using geographical information sources is to understand their format and how to avail them. However,

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PG3D Graphical Interpretation for Real-Time Virtual ApplicationsAnother important feature of the PG3D System lies on its graphic interpretation of the modeled shapes. As mentioned before, PG3DShapes are built from geometries that describe their appearance. To be able to view them in any graphical tool or framework, it is necessary that its structure is previously "translated". However, this operation can become complicated depending on the requirements and potential of the target platform. The database management system chosen was PostgreSQL, using the PostGIS spatial extension, which allows not only the load and storage of geographic information sources, but also the execution of spatial operations in the created data structures. The chosen programming language was PL/PgSQL, which takes advantage of its native implementation in the database to increase the power, flexibility and performance of the created functions. Since this database management system does support neither 3D visualization nor custom file writing capabilities to export the data, a client application was conceived (figure 6). This makes use of.NET framework and C# to provide easy and fast ways to manage, visualize and export the produced environments. The PG3D System is therefore the junction of the PG3D Modeler and this client tool, working in client-server architecture

PG3D Structure as a Key FeaturePG3D operates with the most basic forms of graphical data on which the computer graphics normally operate: vertices and their conjunction in polygonal meshes, especially in triangular meshes. This structure is thus easily integrated with development platforms, graphic editing or viewing, but especially game or virtual world engines. This type of data structure, integrated with capabilities of complex queries on the database, induces increased optimization capabilities. For example, the ability to detect vertices with the same characteristics in large sets of shapes can dramatically reduce the amount of data to be drawn by the graphic card when rendering the entire scene. This type of approach, tempered by some optimization techniques available nowadays, such as vertex buffers and index buffers can allow the visualization of very large urban environments (figure 5), even in real time applications such as metaverse platforms.

Figure 6: PG3D Client Interface

ResultsThe PG3D System was developed in order to facilitate the modeling of virtual urban environments by reducing the human interaction in the process, thus contributing to less effort, less design time and hence lower production costs. It is therefore ideal for applications that make use of this type of content such as digital games and virtual world applications. To demonstrate the advantages stated by the PG3D concept, some tests were performed at various levels.

Figure 5: 10km urban area, featured by PG3D

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Capacity, Quality and Level of DetailAn important factor in modeling is the quality and level of detail of the created elements. To be able to achieve certain levels of detail, it is necessary that the modeling processes are capable to reproduce existing buildings (or at least most of them) with enough precision. The development of this feature was a major goal of the PG3D modeler. An example of a created building is displayed in figure 7.

Data Visualization and ExportThe implementation of the PG3D modeler in databases makes it difficult, if not impossible, to display graphic information directly in the database management system tools. As such, the use of the generated data has to be performed by external applications, such as services or clients that access the database for extraction and subsequent visualization or export of the generated models. Together with the PG3D modeler, they form the PG3D System.

Implementation and TechnologiesPG3Ds full name refers, besides to the reference to its objective, to the technology in which this first prototype was implemented. PG3D is therefore an acronym for the triple PostgreSQL, PostGIS, Procedural Generation 3D.

Figure 7: Model of a house, featuring high detailed windows, shutters and balconies

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The presented model shows that the various elements of the building faade of a house can be defined with great detail. The design of such structures, however, needs the definition of a larger number of production rules, which, in turn, take more time to process. The application of production rules is done in an iterative way, which allows a progressive improvement of the models detail. Due to the possibility to load intermediate states of development of each model, multiple levels of detail of the same environments can be used. This is especially useful in virtual world applications, in order to adapt the displayed detail to the machines capabilities, making the world navigable even in slower ones. This rule operates over the information of the roads, applies an asphalt texture (b) after optimizing it (a), and places the roads on the surface, adapting it to the elevation features (c).BuildingFootprint placePolygonOnCustomSurface('SurfaceDump') //a extrude(double(record(%p),'height')) //b STOC 15% setTexture(@t_Window1) //c 15% setTexture(@t_Window2) 15% setTexture(@t_Window3) 15% setTexture(@t_Window4) 15% setTexture(@t_Window5) 25% setTexture(@t_Window6) ENDSTOC setUV(5,5) //d {hasTag(%p,'Edificio.Top') %each : BuildingTop, %rest : BuildingSides}; //e

Visual Resemblance and AccuracyIn order for a virtual world visitor to be able to recognize the created virtual urban environment, is it important that its elements hold as many similarities to the real ones as possible. This is achieved mostly through the distribution of roads and buildings, but also through a lot by smaller details, such as faade outline and contained features. Due to the limited amount of data sources used until this moment, only the first perception has been achieved (figure 8), so some work in this area is still being developed.

In this step, the building footprints are loaded and placed on the surface, like the roads (a). The information of their heights, also contained on the database, is used to extrude the footprints (b), creating volumes of the buildings with real heights. To introduce variety in their textures, a stochastic method is used to choose them, based on probabilities (c). This way, each texture (except the last) has a 15% probability to be chosen. Afterwards, the UV mapping of the texture is applied based on a fixed size (d). Lastly, the shapes are divided (e): the building sides are saved in a shape called BuildingSides and the top face is saved in a shape called BuildingTop. This new shape is considered in the rule below, which creates a roof-like structure (a) from this top face and applies a red brick texture (b).BuildingTop extrudeTaper(3,5) //a setTexture(@t_RoofRed) //b BuildingRoof;

Figure 8: Comparison of the Boavista Roundabout in Porto, Portugal and its correspondent virtual environment

Definition of modeling processesThe definition of production rules represents the main task to be done by the user intending to obtain procedurally created models. However, such may not always be an easy task, since both data sources and projected models must be carefully analyzed beforehand. Even so, when regarding more basic environments, such as the simple definition of building blocks and streets standing on a surface (figure 9), the rules can be very straightforward and simple. For the following example, three layers corresponding to the surface, road and building, are considered, which contain real world spatial information. The rules that follow have been labeled with letters in order to help their explanation:Surface surfaceOptimize(20,20) //a setTexture(@t_Stone1)SurfaceStone;

The following rules, when applied, produce the example portrayed in figure 9. As it can be seen, even through a small number of production rules, very satisfactory results can be obtained. These simple rules can be applied to as many models as intended in a matter of seconds, a task that could take hours or days when modeled individually with manual tools.

Figure 9: Aliados Avenue in Porto, Portugal

Integration with Virtual World ApplicationsThe development of quick and simple ways to put the created models into practice constitutes one of PG3D main concerns, and such is achieved, as mentioned, by the visualization and export abilities of the PG3D client 1 application. The software itself uses the XNA Framework (figures 4,5,7,8 and 9), a popular game development framework, to display the tridimensional models. Its implementation in high-level languages and powerful features has made XNA quite attractive for a growing number of users, and therefore a recurrent tool for the creation of virtual worlds. Although its employment in

//b //c

The rule above takes the information about the surface (contained in a shape called Surface), optimizes its data structure (a) and applies a texture (b), being its path saved on a variable named Stone1. In the end, the result is saved as a new shape called SurfaceStone (c).placeVertexOnCustomSurface('Surface') //c Roads;Roads surfaceOptimize(20,20) setTexture(@t_Asphalt)

//a//b

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game creation is mostly single player oriented, some 2 attempts are being made regarding massive multiplayer online games (MMORPG).

Figure 12: Open Cobalts Alice and Dancing Girl avatars in a virtual representation of Portos downtown Figure 10: Aliados Avenue in Porto, Portugal, represented in 3 a virtual environment played on Unreal Tournament 3

In this sense, their direct integration with the PG3D System could enjoy the additional possibilities of already implemented runtime model loading and large-scale environment support. In order to employ the obtained models in further platforms, PG3D supports their export to COLLADA4, a popular exchange format for 3D content. Figure 10 shows the use of a PG3D created environment in Unreal Tournament 3, an online multiplayer game. The import procedure consisted simply on loading the COLLADA file using the powerful Unreal Development Kit and defining some properties. For other applications, where a more restricted number of formats is accepted for their content input, the data import cannot always be done directly, being an intermediate format change needed. The popularity of COLLADA has led to a significant support by various authoring tools. This means, that it is not only possible to import and export to various different formats, but to carry manual changes on the procedurally created models, if desired, in order to refine, correct or add further details (figure 11).

Open Cobalt intends to be a platform for collaborative user virtual workspaces, in which the users can easily add new contents and manipulate them in real-time. It is able to import external 3D content in the ASE format, which is a standard ASCII format common to many authoring tools. After converting to this format, a single drag and drop action of the file to the display window is sufficient to import the PG3D generated models into this virtual environment application (figure 12).

CONCLUSIONS AND FUTURE WORKThe PG3D System is still in an alpha phase, but shows enormous potential regarding the procedural modeling for development of virtual representations of real-world urban environments. In short, the PG3D System features: Loading and organization of georreferenced information sources regarding real-world urban spaces; Procedural modeling of tridimensional virtual environments, oriented by user-defined production rules, which operate over these sources; Visualization and export of the generated models for use in multiple games, authoring tools and virtual world applications.

Besides presenting itself as a much faster, simpler and cost-effective method of content creation, the results are likely far more accurate and consistent than if they were created manually. The laborious task of mass modeling is, in such cases, much easily led by procedural methods. On a more technical view, the PG3D concept has demonstrated to induce the following advantages, comparing to other procedural approaches, such as: Quick access to data sources, since it reduces the data access overhead; Greater modeling limits, since it can operate over small sets of data at the time, therefore is not limited by environment size;

Figure 11: Generated urban model processed by the 3Ds 5 Max authoring tool As a further example of a virtual world application, the 6 same models were tested on Open Cobalt , which makes 7 use of the Open Croquet SDK to manage the virtual environments on a large user scale.

1 2 3

http://www.xna.com/ http://levelgrindonline.com/ http://www.unrealtournament.com/

4 5 6 7

http://www.collada.org http://www.autodesk.com/3dsmax http://www.opencobalt.org/ http://www.opencroquet.org/

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Greater safety, since it stores every step on disk and can be recovered even in the case of crash; Easy data source creation and manipulation, due to the availability of database query languages, such as SQL; Easy execution of complex operations through custom queries, derived from the relational database structures and query languages. An example would be the creation of optimized models formats for use in real-time viewing applications. Easy integration with any platform, since the modeling functions are stored in a database and can be accessed by any client or service that intends to enjoy from their procedural modeling capabilities.

Interactive System Generation.

for

Procedural

City

Mller, P., Wonka, P., Haegler, S., Ulmer, A., & Gool, L. V. (2006). Procedural Modeling of Buildings. Paper presented at the ACM SIGGRAPH 2006 Papers. Open Geospatial Consortium. (2010). Simple Features. from http://www.opengeospatial.org/standards/sfa Open Geospatial Consortium Inc. (2006). OpenGIS Implementation Specification for Geographic Information - Simple feature access - Part 1: Common Architecture. In J. R. Herring (Eds.) Parish, Y. I. H., & Mller, P. (2001). Procedural Modeling of Cities. (SIGGRAPH 2001), 301 308 Procedural Inc. (2009). 3D Modelling Software for Urban Environments. Procedural, from http://www.procedural.com/ Prusinkiewicz, P., & Lindenmayer, A. (1996). The Algorithmic Beauty of Plants: SpringerVerlag. Silva, P. B. (2010). Modelao Procedimental para Desenvolvimento de Jogos de Computador. University of Porto, Porto. Stiny, G. (1980). Introduction to shape and shape grammars. Environment and Planning B, 7(3), 343-351. Stiny, G., & Gips, J. (1972). Shape Grammars and the Generative Specification of Painting and Sculpture. Paper presented at the Information Processing '71. Wonka, P., Wimmer, M., Sillion, F., & Ribarsky, W. (2003). Instant Architecture. 22(ACM Trans. Graphics), 669

Despite these advantages, the results still have to be further developed, especially to achieve greater visual resemblance with existing environments. The achievable model quality is high, though their correspondent creation time to attain them is still too elevated for more detailed cases. Although the time to manage the sources is reduced, the modeling operations are still too slow, therefore optimizations still have to be done. The usage of the generated data has been successful, but in order to integrate them more easily with any game, additional formats should be supported in the future. ACKNOWLEDGEMENTS This work is partially supported by the Portuguese government, through the National Foundation for Science and Technology - FCT (Fundao para a Cincia e a Tecnologia) and the European Union (COMPETE, QREN and FEDER) through the project PTDC/EIAEIA/108982/2008 entitled 3DWikiU 3D Wiki for Urban Environments". REFERENCES Bruneton, E., & Neyret, F. (2008). Real-time rendering and editing of vector-based terrains. Computer Graphics Forum, 27(Eurographics 2008), 311-320. Chen, G., Esch, G., Wonka, P., Mller, P., & Zhang, E. (2008). Interactive Procedural Street Modeling. Chomsky, N. (1956). Three Models for the Description of Language. (IRE Trans. Information Theory (2),), 113124 Coelho, A., Bessa, M., Sousa, A. A., & Ferreira, F. N. (2007). Expeditious Modelling of Virtual Urban Environments with Geospatial L-systems. Computer Graphics Forum, 26(4), 769-782. Kelly, G., & McCabe, H. (2007). Citygen: An

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METAVERSEA PROPOSAL FOR THE DEVELOPMENT OF BEHAVIOR OF AUTONOMOUS ENTITIES IN SECOND LIFE

Donizetti Louro1, Mauricio Pontuschka2, Srgio Roberto Pellegrino3Aeronautics Institute of Technology ITA, Computer Science Department Praa Marechal Eduardo Gomes 50 - 12228-900 - So Jos dos Campos So Paulo - Brazil (1,3){don, pell}@ita.br Pontifical Catholic University of So Paulo - PUC-SP, Computer Science Department Rua Marqus de Paranagu, 111 01303-050 So Paulo So Paulo - Brazil (2)[email protected]

AbstractIn this article we study the behavior of autonomous entities in metaverse, by means of Petri nets, aimed to understand, define and implement development tools. When comparing this approach with current technology of objectorientation, we note that the well-known class diagrams do not provide abstractions so adherent to the context of the simulators as Petri Nets.Keywords: Petri Net, entities, behavior, autonomous

IntroductionThe environment of Second Life is one of the experiments with the greatest impact when it concerns man's desire to play at being creative. Contemporary society is marked by a shift in the knowledge acquisition. Therefore, we can observe that many discussion forums ensure the advancement of learning and development tools for immersive environments. This direction, we intend this paper to discuss a proposal to consolidate the creation and construction of autonomous entities in Second Life. 67.5 million Internet users according to Ibope1 / Nielsen in December 2009. In September were 66.3 million. Ie: in just three months came to 1.2 million new Brazilians over 16 years on the Internet. Brazil is the 5th country with the largest number of Internet connections. Thinking about this growing number of users, mainly in Brazil, decided to start a research work on process improvement for implementation in the construction of immersive environments, demystifying and presenting ways to secure software development. In this direction, the simulation system has good and sufficient in the use of certain mathematical techniques, which allow you to mimic the operation of virtually any type of operation, process or permission from the real world. On becoming of their applications "implies modeling simulation of a process or system, so that the model mimics the real systemBrazilian multinational, private equity, IBOPE is a leading market research in Latin America. 68 years ago provides a wide range of information and media studies, public opinion, voting intention, consumption, brand and market behavior.1

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responses in a succession of events that occur over time," Schriber [1974] In other words, "Simulation is the process of designing a model of a real system and conducting experiments with this model in order to understand their behavior and / or evaluate strategies for their operation," Pegden, CD, Shanon, RE, Sadowsky R [1991]. Understanding the Proposal When we navigate in the Second Life environment we can observe that the most participants represented by avatars are exploring the world and not executing tasks by doing some job and work in some activity. We find places with a lot of people talking and communicating but it is difficult to see some people working together and building something that could provide the sense of a well done job. If we would like to make a different place that provides a more collaborative environment we will have to start to think about some important roles that interact and build this place. Let s think, by an example, about playing bowl. We can build a empty place with the bowling lanes and all the objects that are necessary to play the game, but if we think about having some people around playing, talking and serving the players, it could be a more interactive place. Those elements that could act in this environment we call automata objects. These objects could be constructed with its own characteristics and behavior and this will provide the sensation of the world around us. So the sensation that we have when we cross a street and there are cars and other people moving could be represented in these environments. In our experience of crossing a street the other people are just the other people and don t necessarily are avatars controlled by real persons. This idea is to bring movement to the environments and provide a dynamic experience to the visitors, even if we make some visual difference between real avatars and the automata objects. In this line of though, we started to search for a good way of representing models to define the characteristic and behavior of these automata objects, and some answers could be found in our academic activity by observing how the students of different courses understand the activity of software modeling. In this experiment we observed two different courses under the Computer Science

Department of Catholic University of Sao Paulo that are: Computer Science and Technology in Digital Games. Under the Computer Science course realize that the focus is on studying the area of computing in its various aspects including systems development, operating systems, compilers, artificial intelligence among others. We note also that users are quite different and have different sets of concepts, skills and competencies which are linked to perform adequately on each activity to activities relevant to their area. In several courses in the area of technology and accurate, it was found that most comes to software development, but each presents a different process. Realizing that there are different ways to produce software, students come to understand that the production of software is not something static and make it possible to be unified. It is impossible to unify the development process, considering the effort expended by Ivar Jacobson, Booch and James Rumbaugh Grandy trying to write the Unified Method (Unified Method) and realizing that this would not be possible to alter their approach to writing the UML (Unified Modeling Language). Even after finding that it is not possible to adopt a single methodology for developing software for all kinds of problem, we found that the problem only reduced in size, but still persisted. A new attempt was the unification of design models by defining a single language to write computer2 programs. Thus, the Unified Modeling Language is not really a unified language for all software development processes, but rather a comprehensive attempt to unite aspects present in many development methods in a visual language. We note that it is not unique by a counter example that are structured programs that are not expressed in standard UML, or programs written in LISP which use different programming paradigms. Why not have been written under the paradigm of object orientation are not supported by UML. Under the Technology in Digital Games course, the way of thinking of software building it s completely different. The primary data are not numbers and text, but elements in a complexA good analogy to this attempt was the eort of trying to create the Esperanto language as the only world language which would replace any language. This eort misses the cultural aspect rooted in verbal languages which also inuence the way we structure thought.2

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environment. In this way, the models that are concepted by Technology in Digital Games students, naturally uses an object oriented paradigm and several threads of execution in the runtime environment. The Computer Science students have to learn to work with objects while the Technology in Digital Games students already start to work with objects at the first class. In other hand, Computer Science students can build computer software from scratch and they are able to open a simple text editor and start their software. We know that there are different kinds of students and it s risky to affirm that all Computer Science students think the same way, but we are talking about waves and the way the most students of each course work with their software development challenges. We began this paper discussing about the ways of representing a certain content (in this case is software), so we can think a little about the following questions: What is the best paradigm for use in the expression of the metaverse? How best to represent their building models? The choice itself is not a problem, the problem is in the form of thought used in its production, as not all forms of representation through codes and diagrams support our structures of thought. Currently the choice of UML as a form of representation has been very common in virtually all software development. In a quick assessment could refer to this language we choose, but then when we focus specifically the production of computer games we began to encounter problems that are unusual in software in general and thus require a different expression. The Modeling There are several tools for the study of dynamical systems and, according to Samilifard & Wright (2000), "Modeling with Petri nets (PNs) has been widely studied and applied successfully in the areas of dynamic systems. In our case, we will use in discrete simulation. "Thus, we reiterate Peterson (1981), the PNs are important to allow a mathematical representation, analysis models and provide useful information about the structure and dynamic behavior of systems modeled."

With this, based on these work, we are using an elementary model of PNs (or ordinary) of type Place / Transition (LT), as they are characterized by parallelism and synchronization. Decisions to use a modeling of the systems are based on mathematical rigor and the availability of analysis tools. Louro,D., Barufaldi,A., Ferreira,C.(2010) Petri Nets are formed by: The asset called transition ; The liabilities denominated place ; What connects places and transitions called arc. The simulations allow inferences about discrete systems modeled on the condition of not developing its architecture or its construction; it presents conjectures in the validation process, which allows defining and redefining the limits of the system. The remaining checks will be measured in the model development work, as well as its implementation on the suggested model. In discrete simulation, identification and description of processes, the functional point of view, characterize and account for the dynamics of this system. Thus, computer simulation3,, with this application, it is expected to represent the system through a set of processes, each one possessed of certain values as signic elements responsible for all activities in the system. After all, apart from these elements, by which it is perfectly possible to create a discrete model, other elements also perform important with the development and application of simulation techniques. In Petri nets have components such as the transition, which is active and the corresponding any action performed within the system, and the place, which is passive and is related to some state variable of the system. According to Murata (1989), "the realization of actions is associated with preconditions or conditions of the state variables of the system, ie, there is a relationship between places and transitions, which enables you to perform some action." Thus, these places and transitions are vertices of the graph associated with Petri nets and establish connections by arcs that will be indispensable in the analysis process. Louro,D., Barufaldi, A., Ferreira, C.The computer simulation of systems, or simply simulation, is the use of certain mathematical techniques, used in digital computers, which allow you to mimic the operation of virtually any type of operation or process (systems) in the real world.3

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(2010) In this context, initially held numerous tests, types of modeling and analysis of systems that do not exhaust the possibilities for development of specific modeling tools, but want to contribute to a proposed application in immersive environments. Thus, according Samilifard & Wright (2000), Petri nets have been widely studied and applied successfully in the area of discrete event dynamical systems, which are characterized by parallelism and synchronization." According to Nash4 in his Nash Equilibrium5 paper [NAS50] that we have a game we should have several elements such as: two contestants vying for a particular feature and the contestant who wins the win. Thus, virtually all Computer Games have elements with a high level of need and evidence of concurrent execution so they can implement the independence of actions between the players and the feature that interacts with the environment and with the players and at the same time has its identity well defined. These elements behave as autonomous elements in the same shared environment that is the essence of electronic simulation environments. This problem, although it was presented in the context of the computer games is a generic problem that is the modeling and implementation of Distributed Discrete Systems. This problem is in the modeling, definition and implementation elements such as simulators and autonomous4

characters in Metaverses.

virtual

environments

and

Discrete Distributed Systems are dynamic systems that evolve with the occurrence of physical events in time intervals, usually irregular and unknown. The occurrence of an event because, in general, an internal change in the system and these changes may be observable or not by the user [CURY01]. There are several diagra

Proceedings SLACTIONS2010 International Conference

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