Citywide: Supporting Interactive Digital Experiences Across Physical Space

The Citywide project is exploring ways in which technology can provide people with rich and engaging digital experiences as they move through physical space, including historical experiences, performances and games. This paper describes some initial results and experiences with this project based upon two prototype demonstrators. In the first, we describe an application in which a search party explores an archaeological site, uncovering enacted scenes within the virtual world that are of a historical relevance to their particular physical location. In the second, we describe a museum experience where participants explore an outdoors location, hunting for buried virtual artifacts that they then bring back to a museum for a more detailed study. Our demonstrators employ a varied set of devices, including mobile wireless interfaces for locating hotspots of virtual activity when outdoors, to give different experiences of the virtual world depending upon location, task, available equipment and accuracy of tracking. We conclude by discussing some of the potential advantages of using an underlying shared virtual world to support interactive experiences across extended physical settings.     

Spectral optimization for constituent retrieval in Case 2 waters II: Validation study in the Chesapeake Bay

Coastal waters (Case 2) are generally more optically complex than oceanic waters and contain much higher quantities of colored detrital matter (CDM, a combination of dissolved organic matter and detrital particulates) as well as suspended sediment. Exclusion of CDM in the retrieval can lead to an overestimation of chlorophyll a concentration (C). We present a validation of a Case 2 version of the coupled spectral optimization algorithm (SOA) for simultaneous atmospheric correction and water parameter retrieval using Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite ocean color data. Modeling of water constituents uses the Garver, Siegel and Maritorena (GSM) semi-analytic bio-optical model locally tuned for Chesapeake Bay. This includes a parameterization for CDM through its absorption spectrum.SOA-retrieved C and CDM are compared with in situ measurements in Chesapeake Bay. Results are also compared with output from two alternate models 1) the standard algorithm (Std) and 2) the standard atmospheric correction combined with the locally tuned GSM model (StdGSM). The comparisons indicate that the SOA is a viable alternative to both given models in Chesapeake Bay. In contrast, StdGSM appears to require improvement before it can be considered for operational use in these waters. Perhaps the most important result is the high-quality of CDM retrievals with the SOA. They suggest that there is value added using the SOA method in Chesapeake waters, as the Std method does not retrieve CDM. In a companion paper we describe in detail the model implementation, and its accuracy and limitations when applied to the Chesapeake Bay.     

Spectral optimization for constituent retrieval in Case 2 waters I: Implementation and performance

We describe in detail the implementation of the spectral optimization algorithm (SOA) for Case 2 waters for processing of ocean color data. This algorithm uses aerosol models and a bio-optical reflectance model to provide the top-of atmosphere (TOA) reflectance. The parameters of both models are then determined by fitting the modeled TOA reflectance to that observed from space, using non-linear optimization. The algorithm will be incorporated into the SeaDAS software package as an optional processing switch of the Multi-Sensor Level-1 to Level-2 code. To provide potential users with an understanding of the accuracy and limitations of the algorithm, we generated a synthetic data set and tested the performance of the SOA with both correct and incorrect bio-optical model parameters. Application of the SOA to actual SeaWiFS data in the Lower Chesapeake Bay (for which surface measurements were available) showed that 20% errors in the bio-optical model parameters still enabled retrieval of chlorophyll a and the total absorption coefficient of dissolved plus particulate detrital material at 443 nm with an error of less than 30% and 20%, respectively. In a companion paper we present a validation study of the application of the algorithm in the Chesapeake Bay.     

Exploiting perceptual limitations and illusions to support walking through virtual environments in confined physical spaces

Head-mounted displays (HMDs) allow users to immerse in a virtual environment (VE) in which the user’s viewpoint can be changed according to the tracked movements in real space. Because the size of the virtual world often differs from the size of the tracked lab space, a straightforward implementation of omni-directional and unlimited walking is not generally possible. In this article we review and discuss a set of techniques that use known perceptual limitations and illusions to support seemingly natural walking through a large virtual environment in a confined lab space. The concept behind these techniques is called redirected walking. With redirected walking, users are guided unnoticeably on a physical path that differs from the path the user perceives in the virtual world by manipulating the transformations from real to virtual movements. For example, virtually rotating the view in the HMD to one side with every step causes the user to unknowingly compensate by walking a circular arc in the opposite direction, while having the illusion of walking on a straight trajectory. We describe a number of perceptual illusions that exploit perceptual limitations of motion detectors to manipulate the user’s perception of the speed and direction of his motion. We describe how gains of locomotor speed, rotation, and curvature can gradually alter the physical trajectory without the users observing any discrepancy, and discuss studies that investigated perceptual thresholds for these manipulations. We discuss the potential of self-motion illusions to shift or widen the applicable ranges for gain manipulations and to compensate for over- or underestimations of speed or travel distance in VEs. Finally, we identify a number of key issues for future research on this topic.     

Estimation of Detection Thresholds for Redirected Walking Techniques

In immersive virtual environments (IVEs), users can control their virtual viewpoint by moving their tracked head and walking through the real world. Usually, movements in the real world are mapped one-to-one to virtual camera motions. With redirection techniques, the virtual camera is manipulated by applying gains to user motion so that the virtual world moves differently than the real world. Thus, users can walk through large-scale IVEs while physically remaining in a reasonably small workspace. In psychophysical experiments with a two-alternative forced-choice task, we have quantified how much humans can unknowingly be redirected on physical paths that are different from the visually perceived paths. We tested 12 subjects in three different experiments: (E1) discrimination between virtual and physical rotations, (E2) discrimination between virtual and physical straightforward movements, and (E3) discrimination of path curvature. In experiment E1, subjects performed rotations with different gains, and then had to choose whether the visually perceived rotation was smaller or greater than the physical rotation. In experiment E2, subjects chose whether the physical walk was shorter or longer than the visually perceived scaled travel distance. In experiment E3, subjects estimate the path curvature when walking a curved path in the real world while the visual display shows a straight path in the virtual world. Our results show that users can be turned physically about 49 percent more or 20 percent less than the perceived virtual rotation, distances can be downscaled by 14 percent and upscaled by 26 percent, and users can be redirected on a circular arc with a radius greater than 22 m while they believe that they are walking straight.     

An educational interactive numerical model of the Chesapeake Bay

Scientists use sophisticated numerical models to study ocean circulation and other physical systems, but the complex nature of such simulation software generally make them inaccessible to non-expert users. In principle, however, numerical models represent an ideal teaching tool, allowing users to model the response of a complex system to changing conditions. We have designed an interactive simulation program that allows a casual user to control the forcing conditions applied to a numerical ocean circulation model using a graphical user interface, and to observe the results in real-time. This program is implemented using the Regional Ocean Modeling System (ROMS) applied to the Chesapeake Bay. Portions of ROMS were modified to facilitate user interaction, and the user interface and visualization capabilities represent new software development. The result is an interactive simulation of the Chesapeake Bay environment that allows a user to control wind speed and direction along with the rate of flow from the rivers that feed the bay. The simulation provides a variety of visualizations of the response of the system, including water height, velocity, and salinity across horizontal and vertical planes.     

Virtual Bounds: a teleoperated mixed reality

This paper introduces a mixed reality workspace that allows users to combine physical and computer-generated artifacts, and to control and simulate them within one fused world. All interactions are captured, monitored, modeled and represented with pseudo-real world physics. The objective of the presented research is to create a novel system in which the virtual and physical world would have a symbiotic relationship. In this type of system, virtual objects can impose forces on the physical world and physical world objects can impose forces on the virtual world. Virtual Bounds is an exploratory study allowing a physical probe to navigate a virtual world while observing constraints, forces, and interactions from both worlds. This scenario provides the user with the ability to create a virtual environment and to learn to operate real-life probes through its virtual terrain.     

Grasping,communicating, understanding: Connecting reality and virtuality

Several simulation projects in the area of production and logistics indicated that, although we have sophisticated input and output devices for computer supported modelling, physical models still play an important role for cognition and communication. We therefore introduce the concept of a Graspable User Interface that aims at combining two model worlds, the one inside the computer and a corresponding physical one in the outside world. Sensored user hands will couple physical objects of the real world with virtual objects, thus allowing fairly unrestricted manipulation and expression. In this way modelling with real physical objects can create an abstract virtual model. Some applications of this concept are presented. A further perspective for a new action oriented communication and learning with artifacts is envisioned.     

Cognitive revolution, virtuality and good life

We are living in an era when the focus of human relationships with the world is shifting from execution and physical impact to control and cognitive/informational interaction. This emerging, increasingly informational world is our new ecology, an infosphere that presents the grounds for a cognitive revolution based on interactions in networks of biological and artificial, intelligent agents. After the industrial revolution, which extended the human body through mechanical machinery, the cognitive revolution extends the human mind/cognition through information-processing machinery. These novel circumstances come with new qualities and preferences demanding new conceptualizations. We have some work ahead of us to establish value systems and practices extended from the real to the increasingly virtual/info-computational. This paper first presents a current view of the virtual versus the real and then offers an interpretation framework based on an info-computational understanding of cognition in which agency implies computational processing of informational structures of the world as an infosphere. The notion of “good life” is discussed in light of different ideals of well-being in the infosphere, connecting virtuality as a space of potential and alternative worlds for an agent for whom the reality is a space of actual experiences, in the sense of Deleuze. Even though info-computational framework enables us to see both the real world and the diversity of virtual worlds in terms of computational processes on informational structures, based on a distinct layered cognitive architecture of all physical agents, there is clear difference between potential worlds of the virtual and actual agent’s experiences made in the real. Info-computationalism enables insight into the mechanisms of infosphere and elucidates its importance as cognitively predominant environment and communication media. The conclusion is that by cocooning ourselves in an elaborate info-computational infrastructure of the virtual, we may be increasingly isolating ourselves from the reality of direct experience of the world. The biggest challenges of the cognitive revolution may not be technological but ethical. They are about the nature of being human and its values.     

Sharing VLNET worlds on the Web

Virtual environments define a new interface for networked multimedia applications. The sense of “presence” in the virtual environment is an important requirement for collaborative activities involving multiple remote users working with social interactions. Using virtual actors within the shared environment is a supporting tool for presence. In this paper, we present a shared virtual life network with virtual humans that provides a natural interface for collaborative working and we describe the bridge we realized between this 3D shared world and the Web through a system of 3D snapshots.     

Physically Based Sound Synthesis for Large-Scale Virtual Environments

By offering a natural, intuitive interface with the virtual world, auditory display can enhance a user's experience in a multimodal virtual environment and further improve the user's sense of presence. However, compared to graphical display, sound synthesis has not been well investigated because of the extremely high computational cost for simulating realistic sounds. The state of the art for sound production in virtual environments is to use recorded sound clips that events in the virtual environment trigger, similar to how recorded animation sequences in the earlier days generated all the character motion in the virtual world. In this article, we describe several techniques for accelerating sound simulation, thereby enabling realistic, physically based sound synthesis for large-scale virtual environments     

Let’s keep in touch online: a Facebook aware virtual human interface

A virtual human is an effective interface for interacting with users and plays an important role in carrying out certain tasks. As social networking sites are getting more and more popular, we propose a Facebook aware virtual human. The social networking sites are used to empower virtual humans for interpersonal conversational interaction in this paper. We combine Internet world, physical world and 3D virtual world together to create a new interface for users to interact with an autonomous virtual human which can behave like a real modern human. In order to take advantages of social networking sites, virtual human gathers information of a user from its profile, its likes, dislikes and gauge mood from most recent status update. In two user studies, we investigated whether and how this new interface can enhance human–virtual human interaction. Some positive results concluded from these studies will be guidelines on research and development of future virtual human interfaces.     

A Comprehensive Review of Redirected Walking Techniques: Taxonomy,Methods, and Future Directions

Virtual reality (VR) allows users to explore and experience a computer-simulated virtual environment so that VR users can be immersed in a totally artificial virtual world and interact with arbitrary virtual objects. However, the limited physical tracking space usually restricts the exploration of large virtual spaces, and VR users have to use special locomotion techniques to move from one location to another. Among these techniques, redirected walking (RDW) is one of the most natural locomotion techniques to solve the problem based on near-natural walking experiences. The core idea of the RDW technique is to imperceptibly guide users on virtual paths, which might vary from the paths they physically walk in the real world. In a similar way, some RDW algorithms imperceptibly change the structure and layout of the virtual environment such that the virtual environment fits into the tracking space. In this survey, we first present a taxonomy of existing RDW work. Based on this taxonomy, we compare and analyze both contributions and shortcomings of the existing methods in detail, and find view manipulation methods offer satisfactory visual effect but the experience can be interrupted when users reach the physical boundaries, while virtual environment manipulation methods can provide users with consistent movement but have limited application scenarios. Finally, we discuss possible future research directions, indicating combining artificial intelligence with this area will be effective and intriguing.     

Turing's legacy for the Internet

In 1936, when the world was computerless, Alan Turing invented the first virtual machine, now called the Universal Turing Machine (A. Turing, 1936). This concept provided a common ground for a theoretical exploration of the computable. Today, in a world with millions of computers linked to form a global computing network, we are again contemplating the virtues of virtual machines. Will a virtual machine, executing on millions of physical computing devices, be as useful in computing practice as Turing's machine is in computer theory? The author argues that it will and that its coming is inevitable. These considerations pertain to the delivery systems part of the Internet architecture which is presented     

虚拟场景中环境声源仿真技术综述

环境声音作为日常生活中分布最为广泛的一类声音,是人们获取外部信息的重要来源.近十几年来,随着用户对虚拟场景真实度要求不断提升,为虚拟场景打造同步、真实的环境音效已成为构建高度沉浸式虚拟环境不可或缺的一部分.其中环境声源仿真作为打造真实感虚拟环境音效的基石,得到了研究人员的广泛关注与探索.与传统的人工声源仿真相比,通过算...     

Physical web interfaces

Physical web interfaces is a concept that attempts to change our relationship to conventional Internet interfaces by providing a framework for bringing virtual processes into the real world. By attaching new physical inputs to things we perceive as truly virtual, we add a socio-critical dimension to the interaction of people and machine. This infiltration helps to augment our understanding of data pathways, explore virtual handicaps, regain control of how we access information, manifest metaphors as real entities, and integrate the Internet into already familiar interfaces. Combining form with function, these projects illustrate how simple interaction can lead to complex outcomes.     

Co-presence, collaboration, and control in environmental studies

In this paper, we describe a framework for synchronous collaborative visualization and remote control in the agricultural domain. The framework builds on “Second Life” (SL), a popular networked online 3D virtual world, where users are represented as avatars (graphical self-representations). Co-presence in SL takes the form of instant (real-time) two-way interaction among two or more avatars. The aim of our work is to facilitate co-presence for sharing knowledge and exchanging wisdom about environmental practices. In order to establish a realistic simulated context for communication in SL, virtual counterparts of real devices are created in the virtual world. Specifically, we aim to represent field servers that sense and monitor fields such as rice paddies and vineyards. The Twin-World Mediator (TWM) is developed in order to replicate the behavior of real devices in virtual counterparts, and to facilitate seamless communication between real and virtual world. The TWM is an easy-to-use, extensible, and flexible communication framework. A small study demonstrated how the TWM can support collaboration and experience sharing in the agricultural domain.

Spatial proximity to others determines how humans inhabit virtual worlds

Highly immersive three-dimensional virtual worlds have emerged as a popular medium for human social interactions. These environments enable multimodal sensory engagement and provide an immersive graphical representation of physical space where users can interact via avatars. However, when compared to two-dimensional virtual settings such as chats, virtual worlds impose constraints on social interactions due to the physical distance between individuals. Using the popular platform of Second Life as a model, we examined how humans manage this interindividual distance in virtual worlds. Taking advantage of methods developed in population ecology, we investigated how avatars are distributed in relation to each other to populate a virtual world. Our results revealed a striking dichotomy in the spatial relationships between avatars. Considerable aggregation, largely independent of population density, was observed alongside surprisingly marked physical isolation. These findings demonstrate that the spatial proximity to others determines how humans inhabit virtual worlds.     

Learning in serious virtual worlds: Evaluation of learning effectiveness and appeal to students in the E-Junior project

The objective of this study is to present and to evaluate the E-Junior application: a serious virtual world (SVW) for teaching children natural science and ecology. E-Junior was designed according to pedagogical theories and curricular objectives to help children learn about the Mediterranean Sea and its environmental issues while playing. In this study, we present data about the E-Junior evaluation. A class in a serious virtual world (virtual group) was compared with a traditional type of class (traditional group) that contained identical learning objectives and contents but lacked a gaming aspect. Data collection consisted of quantitative and qualitative measures on a sample of 48 children. With regards to learning effectiveness, the results showed that the serious virtual world does not present statistically significant differences with the traditional type of class. However, students from the virtual group reported enjoying the class more, being more engaged, and having greater intentions to participate than students from the traditional group. The plausible explanation for this can be found in the qualitative data. The implications of these results and improvement proposals are also discussed in this work.