International Journal of Computer Games Technology http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. A Practical Approach for Identity-Embodied 3D Artistic Face Modeling Tue, 24 Jun 2014 08:09:41 +0000 http://www.hindawi.com/journals/ijcgt/2014/781950/ This paper describes a practical technique for 3D artistic face modeling where a human identity can be inserted into a 3D artistic face. This approach can automatically extract the human identity from a 3D human face model and then transfer it to a 3D artistic face model in a controllable manner. Its core idea is to construct a face geometry space and a face texture space based on a precollected 3D face dataset. Then, these spaces are used to extract and blend the face models together based on their facial identities and styles. This approach can enable a novice user to interactively generate various artistic faces quickly using a slider control. Also, it can run in real-time on an off-the-shelf computer without GPU acceleration. This approach can be broadly used in various 3D artistic face modeling applications such as a rapid creation of a cartoon crowd with different cartoon characters. Tanasai Sucontphunt Copyright © 2014 Tanasai Sucontphunt. All rights reserved. A New Methodology of Design and Development of Serious Games Sun, 01 Jun 2014 09:27:32 +0000 http://www.hindawi.com/journals/ijcgt/2014/817167/ The development of a serious game requires perfect knowledge of the learning domain to obtain the desired results. But it is also true that this may not be enough to develop a successful serious game. First of all, the player has to feel that he is playing a game where the learning is only a consequence of the playing actions. Otherwise, the game is viewed as boring and not as a fun activity and engaging. For example, the player can catch some items in the scenario and then separate them according to its type (i.e., recycle them). Thus, the main action for player is catching the items in the scenario where the recycle action is a second action, which is viewed as a consequence of the first action. Sometimes, the game design relies on a detailed approach based on the ideas of the developers because some educational content are difficult to integrate in the games, while maintaining the fun factor in the first place. In this paper we propose a new methodology of design and development of serious games that facilitates the integration of educational contents in the games. Furthermore, we present a serious game, called “Clean World”, created using this new methodology. André F. S. Barbosa, Pedro N. M. Pereira, João A. F. F. Dias, and Frutuoso G. M. Silva Copyright © 2014 André F. S. Barbosa et al. All rights reserved. Unifying Rigid and Soft Bodies Representation: The Sulfur Physics Engine Thu, 29 May 2014 00:00:00 +0000 http://www.hindawi.com/journals/ijcgt/2014/485019/ Video games are (also) real-time interactive graphic simulations: hence, providing a convincing physics simulation for each specific game environment is of paramount importance in the process of achieving a satisfying player experience. While the existing game engines appropriately address many aspects of physics simulation, some others are still in need of improvements. In particular, several specific physics properties of bodies not usually involved in the main game mechanics (e.g., properties useful to represent systems composed by soft bodies), are often poorly rendered by general-purpose engines. This issue may limit game designers when imagining innovative and compelling video games and game mechanics. For this reason, we dug into the problem of appropriately representing soft bodies. Subsequently, we have extended the approach developed for soft bodies to rigid ones, proposing and developing a unified approach in a game engine: Sulfur. To test the engine, we have also designed and developed “Escape from Quaoar,” a prototypal video game whose main game mechanic exploits an elastic rope, and a level editor for the game. Dario Maggiorini, Laura Anna Ripamonti, and Federico Sauro Copyright © 2014 Dario Maggiorini et al. All rights reserved. Dead Reckoning Using Play Patterns in a Simple 2D Multiplayer Online Game Mon, 12 May 2014 08:37:42 +0000 http://www.hindawi.com/journals/ijcgt/2014/138596/ In today’s gaming world, a player expects the same play experience whether playing on a local network or online with many geographically distant players on congested networks. Because of delay and loss, there may be discrepancies in the simulated environment from player to player, likely resulting in incorrect perception of events. It is desirable to develop methods that minimize this problem. Dead reckoning is one such method. Traditional dead reckoning schemes typically predict a player’s position linearly by assuming players move with constant force or velocity. In this paper, we consider team-based 2D online action games. In such games, player movement is rarely linear. Consequently, we implemented such a game to act as a test harness we used to collect a large amount of data from playing sessions involving a large number of experienced players. From analyzing this data, we identified play patterns, which we used to create three dead reckoning algorithms. We then used an extensive set of simulations to compare our algorithms with the IEEE standard dead reckoning algorithm and with the recent “Interest Scheme” algorithm. Our results are promising especially with respect to the average export error and the number of hits. Wei Shi, Jean-Pierre Corriveau, and Jacob Agar Copyright © 2014 Wei Shi et al. All rights reserved. Modeling a Virtual World for the Educational Game Calangos Thu, 24 Apr 2014 08:41:41 +0000 http://www.hindawi.com/journals/ijcgt/2014/382396/ Ecology plays a central role in biology and deserves special attention in scientific education. Nonetheless, the teaching and learning of ecology face a number of difficulties. In order to tackle these difficulties, electronic games have recently been used to mediate ecology learning. This paper presents an electronic game that fulfills these gaps in order to make the students’ work with ecological concepts more concrete, active, and systematic. The paper presents the computational model of the ecological system included in the game, based on a real ecological case, a sand dune ecosystem located in the semiarid Caatinga biome, namely, the sand dunes of the middle São Francisco River, in the state of Bahia, Brazil. It includes various ecological relationships between endemic lizards and the physical environment, preys, predators, cospecifics, and plants. The engine of the game simulates the physical conditions of the ecosystem (dune topography and climate conditions with their circadian and circannual cycles), its biota (plant species and animal species), and ecological relationships (predator-prey encounters, cospecific relationships). We also present results from one classroom study of a teaching sequence structured around Calangos, which showed positive outcomes regarding high school students’ understanding of thermal regulation in ectothermic animals. Angelo C. Loula, Leandro N. de Castro, Antônio L. Apolinário Jr., Pedro L. B. da Rocha, Maria da Conceição L. Carneiro, Vanessa Perpétua G. S. Reis, Ricardo F. Machado, Claudia Sepulveda, and Charbel N. El-Hani Copyright © 2014 Angelo C. Loula et al. All rights reserved. Neural Network to Solve Concave Games Mon, 10 Mar 2014 13:09:28 +0000 http://www.hindawi.com/journals/ijcgt/2014/249721/ The issue on neural network method to solve concave games is concerned. Combined with variational inequality, Ky Fan inequality, and projection equation, concave games are transformed into a neural network model. On the basis of the Lyapunov stable theory, some stability results are also given. Finally, two classic games’ simulation results are given to illustrate the theoretical results. Zixin Liu and Nengfa Wang Copyright © 2014 Zixin Liu and Nengfa Wang. All rights reserved. Analytical Ballistic Trajectories with Approximately Linear Drag Thu, 30 Jan 2014 09:44:39 +0000 http://www.hindawi.com/journals/ijcgt/2014/463489/ This paper introduces a practical analytical approximation of projectile trajectories in 2D and 3D roughly based on a linear drag model and explores a variety of different planning algorithms for these trajectories. Although the trajectories are only approximate, they still capture many of the characteristics of a real projectile in free fall under the influence of an invariant wind, gravitational pull, and terminal velocity, while the required math for these trajectories and planners is still simple enough to efficiently run on almost all modern hardware devices. Together, these properties make the proposed approach particularly useful for real-time applications where accuracy and performance need to be carefully balanced, such as in computer games. Giliam J. P. de Carpentier Copyright © 2014 Giliam J. P. de Carpentier. All rights reserved. Analyzing the Effect of TCP and Server Population on Massively Multiplayer Games Mon, 20 Jan 2014 06:42:53 +0000 http://www.hindawi.com/journals/ijcgt/2014/602403/ Many Massively Multiplayer Online Role-Playing Games (MMORPGs) use TCP flows for communication between the server and the game clients. The utilization of TCP, which was not initially designed for (soft) real-time services, has many implications for the competing traffic flows. In this paper we present a series of studies which explore the competition between MMORPG and other traffic flows. For that aim, we first extend a source-based traffic model, based on player’s activities during the day, to also incorporate the impact of the number of players sharing a server (server population) on network traffic. Based on real traffic traces, we statistically model the influence of the variation of the server’s player population on the network traffic, depending on the action categories (i.e., types of in-game player behaviour). Using the developed traffic model we prove that while server population only modifies specific action categories, this effect is significant enough to be observed on the overall traffic. We find that TCP Vegas is a good option for competing flows in order not to throttle the MMORPG flows and that TCP SACK is more respectful with game flows than other TCP variants, namely, Tahoe, Reno, and New Reno. Other tests show that MMORPG flows do not significantly reduce their sending window size when competing against UDP flows. Additionally, we study the effect of RTT unfairness between MMORPG flows, showing that it is less important than in the case of network-limited TCP flows. Mirko Suznjevic, Jose Saldana, Maja Matijasevic, Julián Fernández-Navajas, and José Ruiz-Mas Copyright © 2014 Mirko Suznjevic et al. All rights reserved. Desirable Elements for a Particle System Interface Sun, 05 Jan 2014 14:37:49 +0000 http://www.hindawi.com/journals/ijcgt/2014/623809/ Particle systems have many applications, with the most popular being to produce special effects in video games and films. To permit particle systems to be created quickly and easily, Particle System Interfaces (PSIs) have been developed. A PSI is a piece of software designed to perform common tasks related to particle systems for clients, while providing them with a set of parameters whose values can be adjusted to create different particle systems. Most PSIs are inflexible, and when clients require functionality that is not supported by the PSI they are using, they are forced to either find another PSI that meets their requirements or, more commonly, create their own particle system or PSI from scratch. This paper presents three original contributions. First, it identifies 18 features that a PSI should provide in order to be capable of creating diverse effects. If these features are implemented in a PSI, clients will be more likely to be able to accomplish all desired effects related to particle systems with one PSI. Secondly, it introduces a novel use of events to determine, at run time, which particle system code to execute in each frame. Thirdly, it describes a software architecture called the Dynamic Particle System Framework (DPSF). Simulation results show that DPSF possesses all 18 desirable features. Daniel Schroeder and Howard J. Hamilton Copyright © 2014 Daniel Schroeder and Howard J. Hamilton. All rights reserved. Procedural Audio in Computer Games Using Motion Controllers: An Evaluation on the Effect and Perception Mon, 23 Dec 2013 11:28:52 +0000 http://www.hindawi.com/journals/ijcgt/2013/371374/ A study has been conducted into whether the use of procedural audio affects players in computer games using motion controllers. It was investigated whether or not (1) players perceive a difference between detailed and interactive procedural audio and prerecorded audio, (2) the use of procedural audio affects their motor-behavior, and (3) procedural audio affects their perception of control. Three experimental surveys were devised, two consisting of game sessions and the third consisting of watching videos of gameplay. A skiing game controlled by a Nintendo Wii balance board and a sword-fighting game controlled by a Wii remote were implemented with two versions of sound, one sample based and the other procedural based. The procedural models were designed using a perceptual approach and by alternative combinations of well-known synthesis techniques. The experimental results showed that, when being actively involved in playing or purely observing a video recording of a game, the majority of participants did not notice any difference in sound. Additionally, it was not possible to show that the use of procedural audio caused any consistent change in the motor behavior. In the skiing experiment, a portion of players perceived the control of the procedural version as being more sensitive. Niels Böttcher, Héctor P. Martínez, and Stefania Serafin Copyright © 2013 Niels Böttcher et al. All rights reserved. Reconstructing 3D Tree Models Using Motion Capture and Particle Flow Thu, 07 Nov 2013 15:41:59 +0000 http://www.hindawi.com/journals/ijcgt/2013/363160/ Recovering tree shape from motion capture data is a first step toward efficient and accurate animation of trees in wind using motion capture data. Existing algorithms for generating models of tree branching structures for image synthesis in computer graphics are not adapted to the unique data set provided by motion capture. We present a method for tree shape reconstruction using particle flow on input data obtained from a passive optical motion capture system. Initial branch tip positions are estimated from averaged and smoothed motion capture data. Branch tips, as particles, are also generated within a bounding space defined by a stack of bounding boxes or a convex hull. The particle flow, starting at branch tips within the bounding volume under forces, creates tree branches. The forces are composed of gravity, internal force, and external force. The resulting shapes are realistic and similar to the original tree crown shape. Several tunable parameters provide control over branch shape and arrangement. Jie Long and Michael D. Jones Copyright © 2013 Jie Long and Michael D. Jones. All rights reserved. Adaptive-AR Model with Drivers’ Prediction for Traffic Simulation Thu, 26 Sep 2013 15:31:15 +0000 http://www.hindawi.com/journals/ijcgt/2013/904154/ We present a novel model called A2R—“Adaptive-AR”—based on a well-known continuum-based model called AR Aw and Rascle (2000) for the simulation of vehicle traffic flows. However, in the standard continuum-based model, vehicles usually follow the flows passively, without taking into account drivers' behavior and effectiveness. In order to simulate real-life traffic flows, we extend the model with a few factors, which include the effectiveness of drivers' prediction, drivers' reaction time, and drivers' types. We demonstrate that our A2R model is effective and the results of the experiments agree well with experience in real world. It has been shown that such a model makes vehicle flows perform more realistically and is closer to the real-life traffic than AR (short for Aw and Rascle and introduced in Aw and Rascle (2000)) model while having a similar performance. Xuequan Lu, Mingliang Xu, Wenzhi Chen, Zonghui Wang, and Abdennour El Rhalibi Copyright © 2013 Xuequan Lu et al. All rights reserved. Effects of Wind on Virtual Plants in Animation Sun, 15 Sep 2013 13:38:23 +0000 http://www.hindawi.com/journals/ijcgt/2013/674848/ This paper presents the Growth-Flow method for animating the effect of wind on the motion and growth of virtual plant branches and leaves. The method incorporates changes to the growth rate when a plant is exposed to winds with speeds higher than a threshold. In particular, growth rate is reduced in branch elongation, increased in the branch radius, reduced in leaf length, and increased in leaf thickness. In addition, when a plant is exposed to wind for long time periods, the branch growth angle is changed to align more closely with the wind vector. The Growth-Flow method incorporates all these effects on growth and motion due to wind in one algorithm. Tina L. M. Derzaph and Howard J. Hamilton Copyright © 2013 Tina L. M. Derzaph and Howard J. Hamilton. All rights reserved. Comparing Expert Driving Behavior in Real World and Simulator Contexts Sun, 18 Aug 2013 11:08:54 +0000 http://www.hindawi.com/journals/ijcgt/2013/891431/ Computer games are increasingly used for purposes beyond mere entertainment, and current hi-tech simulators can provide quite, naturalistic contexts for purposes such as traffic education. One of the critical concerns in this area is the validity or transferability of acquired skills from a simulator to the real world context. In this paper, we present our work in which we compared driving in the real world with that in the simulator at two levels, that is, by using performance measures alone, and by combining psychophysiological measures with performance measures. For our study, we gathered data using questionnaires as well as by logging vehicle dynamics, environmental conditions, video data, and users' psychophysiological measurements. For the analysis, we used several novel approaches such as scatter plots to visualize driving tasks of different contexts and to obtain vigilance estimators from electroencephalographic (EEG) data in order to obtain important results about the differences between the driving in the two contexts. Our belief is that both experimental procedures and findings of our experiment are very important to the field of serious games concerning how to evaluate the fitness of driving simulators and measure driving performance. Hiran B. Ekanayake, Per Backlund, Tom Ziemke, Robert Ramberg, Kamalanath P. Hewagamage, and Mikael Lebram Copyright © 2013 Hiran B. Ekanayake et al. All rights reserved. Petri Net Model for Serious Games Based on Motivation Behavior Classification Thu, 04 Apr 2013 09:05:49 +0000 http://www.hindawi.com/journals/ijcgt/2013/851287/ Petri nets are graphical and mathematical tool for modeling, analyzing, and designing discrete event applicable to many systems. They can be applied to game design too, especially to design serous game. This paper describes an alternative approach to the modeling of serious game systems and classification of motivation behavior with Petri nets. To assess the motivation level of player ability, this research aims at Motivation Behavior Game (MBG). MBG improves this motivation concept to monitor how players interact with the game. This modeling employs Learning Vector Quantization (LVQ) for optimizing the motivation behavior input classification of the player. MBG may provide information when a player needs help or when he wants a formidable challenge. The game will provide the appropriate tasks according to players’ ability. MBG will help balance the emotions of players, so players do not get bored and frustrated. Players have a high interest to finish the game if the players are emotionally stable. Interest of the players strongly supports the procedural learning in a serious game. Moh. Aries Syufagi, Mochamad Hariadi, and Mauridhi Hery Purnomo Copyright © 2013 Moh. Aries Syufagi et al. All rights reserved. The Brigade Renderer: A Path Tracer for Real-Time Games Sun, 17 Mar 2013 16:12:45 +0000 http://www.hindawi.com/journals/ijcgt/2013/578269/ We present the Brigade renderer: an efficient system that uses the path tracing algorithm to produce images for real-time games. We describe the architecture of the Brigade renderer, and provide implementation details. We describe two games that have been created using Brigade. Jacco Bikker and Jeroen van Schijndel Copyright © 2013 Jacco Bikker and Jeroen van Schijndel. All rights reserved. User Experiences While Playing Dance-Based Exergames and the Influence of Different Body Motion Sensing Technologies Wed, 20 Feb 2013 15:47:12 +0000 http://www.hindawi.com/journals/ijcgt/2013/603604/ Dance Dance Revolution is a pioneering exergame which has attracted considerable interest for its potential to promote regular exercise and its associated health benefits. The advent of a range of different consumer body motion tracking video game console peripherals raises the question whether their different technological affordances (i.e., variations in the type and number of body limbs that they can track) influence the user experience while playing dance-based exergames both in terms of the level of physical exertion and the nature of the play experience. To investigate these issues a group of subjects performed a total of six comparable dance routines selected from commercial dance-based exergames (two routines from each game) on three different consoles. The subjects’ level of physical exertion was assessed by measuring oxygen consumption and heart rate. They also reported their perceived level of exertion, difficulty, and enjoyment ratings after completing each dance routine. No differences were found in the physiological measures of exertion between the peripherals/consoles. However, there were significant variations in the difficulty and enjoyment ratings between peripherals. The design implications of these results are discussed including the tension between helping to guide and coordinate player movement versus offering greater movement flexibility. Alasdair G. Thin, Craig Brown, and Paul Meenan Copyright © 2013 Alasdair G. Thin et al. All rights reserved. Single- versus Multiobjective Optimization for Evolution of Neural Controllers in Ms. Pac-Man Mon, 18 Feb 2013 07:22:24 +0000 http://www.hindawi.com/journals/ijcgt/2013/170914/ The objective of this study is to focus on the automatic generation of game artificial intelligence (AI) controllers for Ms. Pac-Man agent by using artificial neural network (ANN) and multiobjective artificial evolution. The Pareto Archived Evolution Strategy (PAES) is used to generate a Pareto optimal set of ANNs that optimize the conflicting objectives of maximizing Ms. Pac-Man scores (screen-capture mode) and minimizing neural network complexity. This proposed algorithm is called Pareto Archived Evolution Strategy Neural Network or PAESNet. Three different architectures of PAESNet were investigated, namely, PAESNet with fixed number of hidden neurons (PAESNet_F), PAESNet with varied number of hidden neurons (PAESNet_V), and the PAESNet with multiobjective techniques (PAESNet_M). A comparison between the single- versus multiobjective optimization is conducted in both training and testing processes. In general, therefore, it seems that PAESNet_F yielded better results in training phase. But the PAESNet_M successfully reduces the runtime operation and complexity of ANN by minimizing the number of hidden neurons needed in hidden layer and also it provides better generalization capability for controlling the game agent in a nondeterministic and dynamic environment. Tse Guan Tan, Jason Teo, and Kim On Chin Copyright © 2013 Tse Guan Tan et al. All rights reserved. Analysis of Motivational Elements of Social Games: A Puzzle Match 3-Games Study Case Sun, 30 Dec 2012 15:45:23 +0000 http://www.hindawi.com/journals/ijcgt/2012/640725/ The main motivational elements of the social network sites and the social network games will be shown according to studies already existent in the literature, highlighting the elements which motivate the players the most to play social Match 3-type games. Seven games have been analyzed: Diamond Dash, Collapse!Blast, Mystic Ice Blast, Bricks Breaking, Plock, Gem Clix, and Blast!. The results showed that asynchronous time, activities publishing, rewarding system, competition, and social status are the elements which motivate and stimulate the most the players to play. Marcel Toshio Omori and Alan Salvany Felinto Copyright © 2012 Marcel Toshio Omori and Alan Salvany Felinto. All rights reserved. A Guideline for Game Development-Based Learning: A Literature Review Sat, 29 Dec 2012 13:57:25 +0000 http://www.hindawi.com/journals/ijcgt/2012/103710/ This study aims at reviewing the published scientific literature on the topics of a game development-based learning (GDBL) method using game development frameworks (GDFs) with the perspective of (a) summarizing a guideline for using GDBL in a curriculum, (b) identifying relevant features of GDFs, and (c) presenting a synthesis of impact factors with empirical evidence on the educational effectiveness of the GDBL method. After systematically going through the available literature on the topic, 34 relevant articles were selected for the final study. We analyzed the articles from three perspectives: (1) pedagogical context and teaching process, (2) selection of GDFs, and (3) evaluation of the GDBL method. The findings from the 34 articles suggest that GDFs have many potential benefits as an aid to teach computer science, software engineering, art design, and other fields and that such GDFs combined with the motivation from games can improve the students’ knowledge, skills, attitudes, and behaviors in contrast to the traditional classroom teaching. Furthermore, based on the results of the literature review, we extract a guideline of how to apply the GDBL method in education. The empirical evidence of current findings gives a positive overall picture and can provide a useful reference to educators, practitioners, and researchers in the area of game-based learning. Bian Wu and Alf Inge Wang Copyright © 2012 Bian Wu and Alf Inge Wang. All rights reserved. Building Community and Collaboration Applications for MMOGs Tue, 11 Sep 2012 10:58:26 +0000 http://www.hindawi.com/journals/ijcgt/2012/969785/ Supporting collaborative activities among the online players are one of the major challenges in the area of Massively Multiplayer Online Games (MMOG), since they increase the richness of gaming experience and create more engaged communities. To this direction, our study has focused on the provision of services supporting and enhancing the players' in-game community and collaboration activities. We have designed and implemented innovative tools exploiting a game adaptation technology, namely, the In-game Graphical Insertion Technology (IGIT), which permits the addition of web-based applications without any need from the game developers to modify the game at all, nor from the game players to change their game installation. The developed tools follow a design adapted to the MMOG players' needs and are based on the latest advances on Web 2.0 technology. Their provision is performed through the core element of our system, which is the so-called Community Network Game (CNG) Server. One of the important features provided by the implemented system's underlying framework is the utilization of enhanced Peer-to-Peer (P2P) technology for the distribution of user-generated live video streams. In this paper, we focus on the architecture of the CNG Server as well as on the design and implementation of the online community and collaboration tools. George Adam, Christos Bouras, Vaggelis Kapoulas, and Andreas Papazois Copyright © 2012 George Adam et al. All rights reserved. Comparison of Learning Software Architecture by Developing Social Applications versus Games on the Android Platform Tue, 11 Sep 2012 08:30:12 +0000 http://www.hindawi.com/journals/ijcgt/2012/494232/ This paper describes an empirical study where the focus was on discovering differences and similarities in students working on development of social applications versus students working on development of games using the same Android development platform. In 2010-2011, students attending the software architecture course at the Norwegian University of Science and Technology (NTNU) could choose between four types of projects. Independently of the chosen type of project, all students had to go through the same phases, produce the same documents based on the same templates, and follow exactly the same process. This study focuses on one of projects—Android project, to see how much the application domain affects the course project independently of the chosen technology. Our results revealed some positive effects for the students doing game development compared to social application development to learn software architecture, like motivated to work with games, a better focus on quality attributes such as modifiability and testability during the development, production of software architectures of higher complexity, and more productive coding working for the project. However, we did not find significant differences in awarded grade between students choosing the two different domains. Bian Wu and Alf Inge Wang Copyright © 2012 Bian Wu and Alf Inge Wang. All rights reserved. A Framework for Adaptive Game Presenters with Emotions and Social Comments Thu, 06 Sep 2012 11:37:57 +0000 http://www.hindawi.com/journals/ijcgt/2012/929814/ More and more games today try to adjust their gameplay to fit individual players; however, little work has been carried out in the same direction towards game presenter characters. Game commentary should take into account players' personalities along with game progress in order to achieve social player-adapted comment delivery that boosts the overall gameplay, engages the players, and stimulates the audience. In our work, we discuss a framework for implementing artificial game presenter characters that are based on game actions and players' social profiles in order to deliver knowledgeable, socially oriented comments. Moreover, the presented framework supports emotional facial expressions for the presenters, allowing them to convey their emotions and thus be more expressive than the majority of the commentary systems today. We prove our concept by developing a presenter character for multiplayer tabletop board games which we further put under usability evaluation with 9 players. The results showed that game sessions with presenter characters are preferred over the plain version of the game and that the majority of the players enjoy personalized social-oriented comments expressed via multimedia and emotions. Effie Karouzaki and Anthony Savidis Copyright © 2012 Effie Karouzaki and Anthony Savidis. All rights reserved. Dynamic Difficulty Balancing for Cautious Players and Risk Takers Wed, 27 Jun 2012 11:24:01 +0000 http://www.hindawi.com/journals/ijcgt/2012/625476/ Dynamic balancing of game difficulty can help cater for different levels of ability in players. However, performance in some game tasks depends on not only the player's ability but also their desire to take risk. Taking or avoiding risk can offer players its own reward in a game situation. Furthermore, a game designer may want to adjust the mechanics differently for a risky, high ability player, as opposed to a risky, low ability player. In this work, we describe a novel modelling technique known as particle filtering which can be used to model various levels of player ability while also considering the player's risk profile. We demonstrate this technique by developing a game challenge where players are required to make a decision between a number of possible alternatives where only a single alternative is correct. Risky players respond faster but with more likelihood of failure. Cautious players wait longer for more evidence, increasing their likelihood of success, but at the expense of game time. By gathering empirical data for the player's response time and accuracy, we develop particle filter models. These models can then be used in real-time to categorise players into different ability and risk-taking levels. Guy Hawkins, Keith Nesbitt, and Scott Brown Copyright © 2012 Guy Hawkins et al. All rights reserved. More Than Flow: Revisiting the Theory of Four Channels of Flow Fri, 15 Jun 2012 16:01:35 +0000 http://www.hindawi.com/journals/ijcgt/2012/724917/ Flow (FCF) theory has received considerable attention in recent decades. In addition to flow, FCF theory proposed three influential factors, that is, boredom, frustration, and apathy. While these factors have received relatively less attention than flow, Internet applications have grown exponentially, warranting a closer reexamination of the applicability of the FCF theory. Thus, this study tested the theory that high/low levels of skill and challenge lead to four channels of flow. The study sample included 253 online gamers who provided valid responses to an online survey. Analytical results support the FCF theory, although a few exceptions were noted. First, skill was insignificantly related to apathy, possibly because low-skill users can realize significant achievements to compensate for their apathy. Moreover, in contrast with the FCF theory, challenge was positively related to boredom, revealing that gamers become bored with difficult yet repetitive challenges. Two important findings suggest new directions for FCF theory. Ching-I Teng and Han-Chung Huang Copyright © 2012 Ching-I Teng and Han-Chung Huang. All rights reserved. Development of Embedded CAPTCHA Elements for Bot Prevention in Fischer Random Chess Mon, 04 Jun 2012 10:12:10 +0000 http://www.hindawi.com/journals/ijcgt/2012/178578/ Cheating in chess can take many forms and has existed almost as long as the game itself. The advent of computers has introduced a new form of cheating into the game. Thanks to the computational power of modern-day computers, a player can use a program to calculate thousands of moves for him or her, and determine the best possible scenario for each move and countermove. These programs are often referred to as “bots,” and can even play the game without any user interaction. In this paper, we describe a methodology aimed at preventing bots from participating in online chess games. The proposed approach is based on the integration of a CAPTCHA protocol into a game scenario, and the subsequent inability of bots to accurately track the game states. This is achieved by rotating the images of the individual chess pieces and adjusting their resolution in an attempt to render them unreadable by a bot. Feedback from users during testing shows that there is minimal impact on their ability to play the game. Players rated the difficulty of reading the pieces on a scale of one to ten, with an average rank of 6.5. However, the average number of moves to adjust to the distorted pieces was only 3.75. This tells us that, although it is difficult to read the pieces at first, it is easy to adjust quickly to the new image. Ryan McDaniel and Roman V. Yampolskiy Copyright © 2012 Ryan McDaniel and Roman V. Yampolskiy. All rights reserved. Pose Space Surface Manipulation Tue, 15 May 2012 19:36:04 +0000 http://www.hindawi.com/journals/ijcgt/2012/596953/ Example-based mesh deformation techniques produce natural and realistic shapes by learning the space of deformations from examples. However, skeleton-based methods cannot manipulate a global mesh structure naturally, whereas the mesh-based approaches based on a translational control do not allow the user to edit a local mesh structure intuitively. This paper presents an example-driven mesh editing framework that achieves both global and local pose manipulations. The proposed system is built with a surface deformation method based on a two-step linear optimization technique and achieves direct manipulations of a model surface using translational and rotational controls. With the translational control, the user can create a model in natural poses easily. The rotational control can adjust the local pose intuitively by bending and twisting. We encode example deformations with a rotation-invariant mesh representation which handles large rotations in examples. To incorporate example deformations, we infer a pose from the handle translations/rotations and perform pose space interpolation, thereby avoiding involved nonlinear optimization. With the two-step linear approach combined with the proposed multiresolution deformation method, we can edit models at interactive rates without losing important deformation effects such as muscle bulging. Yusuke Yoshiyasu and Nobutoshi Yamazaki Copyright © 2012 Yusuke Yoshiyasu and Nobutoshi Yamazaki. All rights reserved. Concert Viewing Headphones Tue, 07 Feb 2012 08:01:23 +0000 http://www.hindawi.com/journals/ijcgt/2011/612535/ An audiovisual interface equipped with a projector, an inclina-tion sensor, and a distance sensor for zoom control has been developed that enables a user to selectively view and listen to specific performers in a video-taped group performance. Dubbed Concert Viewing Headphones, it has both image and sound processing functions. The image processing extracts the portion of the image indicated by the user and projects it free of distortion on the front and side walls. The sound processing creates imaginary microphones for those performers without one so that the user can hear the sound from any performer. Testing using images and sounds captured using a fisheye-lens camera and 37 lavalier microphones showed that sound locali-zation was fastest when an inverse square function was used for the sound mixing and that the zoom function was useful for locating the desired sound performance. Kazuya Atsuta, Masatoshi Hamanaka, and SeungHee Lee Copyright © 2011 Kazuya Atsuta et al. All rights reserved. Epitomize Your Photos Mon, 06 Feb 2012 17:33:44 +0000 http://www.hindawi.com/journals/ijcgt/2011/706893/ With the rapid growth of digital photography, sharing of photos with friends and family has become very popular. When people share their photos, they usually organize them into albums according to events or places. To tell the story of some important events in one’s life, it is desirable to have an efficient summarization tool which can help people to receive a quick overview of an album containing large number of photos. In this paper, we present and analyze an approach for photo album summarization through a novel social game “Epitome” as a Facebook application. This social game can collect research data, and, at the same time, it provides a collage or a cover photo of the user’s photo album, while the user enjoys playing the game. The proof of concept of the proposed method is demonstrated through a set of experiments on several photo albums. As a benchmark comparison to this game, we perform automatic visual analysis considering several state-of-the-art features. We also evaluate the usability of the game by making use of a questionnaire on several subjects who played the “Epitome” game. Furthermore, we address privacy issues concerning shared photos in Facebook applications. Peter Vajda, Ivan Ivanov, Jong-Seok Lee, and Touradj Ebrahimi Copyright © 2011 Peter Vajda et al. All rights reserved. Enhancing a Commercial Game Engine to Support Research on Route Realism for Synthetic Human Characters Thu, 02 Feb 2012 14:11:37 +0000 http://www.hindawi.com/journals/ijcgt/2011/819746/ Generating routes for entities in virtual environments, such as simulated vehicles or synthetic human characters, is a long-standing problem, and route planning algorithms have been developed and studied for some time. Existing route planning algorithms, including the widely used A* algorithm, are generally intended to achieve optimality in some metric, such as minimum length or minimum time. Comparatively little attention has been given to route realism, defined as the similarity of the algorithm-generated route to the route followed by real humans in the same terrain with the same constraints and goals. Commercial game engines have seen increasing use as a context for research. To study route realism in a game engine, two developments were needed: a quantitative metric for measuring route realism and a game engine able to capture route data needed to compute the realism metric. Enhancements for recording route data for both synthetic characters and human players were implemented within the Unreal Tournament 2004 game engine. A methodology for assessing the realism of routes and other behaviors using a quantitative metric was developed. The enhanced Unreal Tournament 2004 game engine and the realism assessment methodology were tested by capturing data required to calculate a metric of route realism. Gregg T. Hanold and Mikel D. Petty Copyright © 2011 Gregg T. Hanold and Mikel D. Petty. All rights reserved.