bluuebunny/crossref_metadata_2025 huggingface dataset:
The Software Required for the Computer Generation of Virtual Environments
Authors: Zyda Michael J. , Pratt David R. , Falby John S. , Lombardo Chuck , Kelleher Kristen M.
Published: December 2015

The first phase of virtual world development has focused on the novel hardware (3-D input and 3-D output) and the graphics demo. The second phase of virtual worlds development will be to focus in on the more significant part of the problem, the software bed underlying “real” applications. The focus of this paper is on the software required to support large scale, networked, multiparty virtual environments. We discuss navigation (virtual camera view point control and its coupling to real-time, hidden surface elimination), interaction (software for constructing a dialogue from the inputs read from our devices and for applying that dialogue to display changes), communication (software for passing changes in the world model to other players on the network, and software for allowing the entry of previously undescribed players into the system), autonomy (software for playing autonomous agents in our virtual world against interactive players), scripting (software for recording, playing back, and multitracking previous play against live or autonomous players, with autonomy provided for departures from the recorded script), and hypermedia integration (software for integrating hypermedia data—audio, compressed video, with embedded links—into our geometrically described virtual world). All of this software serves as the base for the fully detailed, fully interactive, seamless environment of the third phase of virtual world development. We discuss the development of such software by describing how a real system, the NPSNET virtual world, is being constructed.
Social Interaction and Social Development in Virtual Environments
Authors: Stone Valerie E.
Published: December 2015

Like most new technologies, virtual reality (VR) has been the subject of a great deal of idealization. This paper both debunks that idealization by discussing some problems that certain types of VR could cause and emphasizes how other types of VR could bring the technology closer to its ideal. Virtual reality is divided into four types: social (there are real other people to interact with), nonsocial (other interactants are simulations of people), creative (users can create elements in the virtual environment), and noncreative (users interact with a fixed environment created for them). Nonsocial VR may cause problems by making it difficult for children and adolescents to learn social skills. Noncreative VR is problematic because it places limits on users' creativity and freedom. Engineers developing VR technology are encouraged to develop social and creative VR.
Scanned Laser Displays for Virtual Reality:A Feasibility Study
Authors: Holmgren Douglas E. , Robinett Warren
Published: December 2015

Technologies applicable toward a display system in which a laser is raster scanned on the viewer's retina are reviewed. The properties of laser beam propagation and the inherent resolution of a laser scanning system are discussed. Scanning techniques employing rotating mirrors, galvanometer scanners, acoustooptic deflectors, and piezoelectric deflectors are described. Resolution, speed, deflection range, and physical size are strongly coupled properties of these technologies. A radiometric analysis indicates that eye safety would not be a problem in a retina-scanning system. For head-mounted display applications, a monochromatic system employing a laser diode source with acoustooptic and galvanometer scanners is deemed most practical at the present time. A resolution of 1000 × 1000 pixels at 60 frames per second should be possible with such a monochromatic system using currently available off-the-shelf components. A full-color scanned-laser display suitable for head-mounted display use is not judged feasible to build at this time with off-the-shelf components.
Optimized Fingertip Mapping:A General Algorithm for Robotic Hand Teleoperation
Authors: Rohling Robert N. , Hollerbach John M. , Jacobsen Stephen C.
Published: December 2015

An optimized fingertip mapping (OFM) algorithm has been developed to transform human hand poses into robot hand poses. It has been implemented to teleoperate the Utah/MIT Dextrous Hand by a new hand master: the Utah Dextrous Hand Master. The keystone of the algorithm is the mapping of both the human fingertip positions and orientations to the robot fingers. Robot hand poses are generated by minimizing the errors between desired human fingertip positions and orientations and possible robot fingertip positions and orientations. Differences in the fingertip workspaces that arise from kinematic dissimilarities between the human and robot hands are accounted for by the use of a priority based mapping strategy. The OFM gives first priority to the human fingertip position goals and the second to orientation.
A Survey of Virtual Reality in Japan
Authors: Watson Benjamin
Published: December 2015

The NSF Summer Institute in Japan program sends about 60 graduate students of all disciplines to Japan each summer. For two months, students participate in research at host labs, visit conferences and other labs of interest, and receive Japanese language and cultural instruction. Full financial support is provided by the American and Japanese governments. During the summer of 1993, the author participated in this program and took the opportunity to visit the Japanese virtual reality research community. He attended two virtual reality conferences and toured more than a dozen labs. After the program, he made short visits to VR and graphics labs in PR China and South Korea. This paper gives a detailed account of these experiences.
BrickNet: A Software Toolkit for Network-Based Virtual Worlds
Authors: Singh Gurminder , Serra Luis , Png Willie , Ng Hern
Published: December 2015

Network-based virtual worlds allow multiple virtual worlds connected on a network to share information with one another. The development effort required to produce a network-based virtual world is quite large. The BrickNet toolkit simplifies this development by providing the standard facilities required by a wide range of network-based virtual worlds. It provides support for graphical, behavioral and network modeling of virtual worlds in an object-oriented fashion. BrickNet enables graphic objects to be maintained, managed, and used efficiently, and permits objects to be shared by multiple virtual worlds. In this paper, the architecture and implementation of BrickNet are described.
Cybertokyo: A Survey of Public VRtractions
Authors: Cohen Michael
Published: December 2015

As in the Bauhaus movement of the 1930s, artists and engineers are working together on commercial industrial (hardware) and postindustrial (software) design. Japan, a world leader in research and development areas like display technology and robotics, is a fertile environment in which VR [known here sometimes as AR (for artificial reality)] can flourish, both in labs and studios, and as consumer products and services: a confluence of theme parks, amusement centers, retail outlets, and home computer and media centers. Emphasizing the capture, transmission, and reproduction of experience, (literally) sensational VR is upon us, to simulate and stimulate. If it is hyped, or hyper, it is happening around Tokyo. Here is a selective guide to meta-holo-attractions open to the public in “The Big Orange.”
Visual Creation of Virtual Design Environments and Virtual Worlds Research at ISS
Authors: Singh Gurminder , Serra Luis , Fairchild Kim , Poston Timothy
Published: December 2015

Developing virtual worlds using toolkits and conventional programming-based approaches is a tedious, time-consuming, and often frustrating task. Too much learning of the toolkits and the basic development technology is necessary before the development can start. Even after that, it takes a long time to develop, test, and modify virtual worlds. At ISS, we are following a highly interactive and visual approach to virtual world construction, which allows virtual world designers to work with high-level concepts. This approach facilitates exploration in design and rapid prototyping. To achieve our goal, we are focusing on the following four base technologies: Bricks, a toolkit to support the development of virtual worlds; WorldNet, a toolkit to support the development of network-based virtual worlds; VizNet, a system that helps visualize a large collection of objects; and the Virtual Workbench, a crafting environment that uses virtual reality to build and manage objects.
The Virtual Environment Performance Assessment Battery (VEPAB):Development and Evaluation
Authors: Lampton Donald R. , Knerr Bruce W. , Goldberg Stephen L. , Bliss James P. , Moshell J. Michael , Blau Brian S.
Published: December 2015

The Virtual Environment Performance Assessment Battery (VEPAB) is a set of tasks developed to support research on training applications of virtual environment (VE) technology. VEPAB measures human performance on vision, locomotion, tracking, object manipulation, and reaction time tasks performed in three-dimensional, interactive VEs. It can be used to provide a general orientation for interacting in VEs and to determine both entry level performance and skill acquisition of users. In addition, VEPAB allows comparison of task performance, side effects and aftereffects, and subjective reactions across different VE systems. By providing benchmarks of human performance, VEPAB can promote continuity in training research involving different technologies, separate research facilities, and dissimilar subject populations. This paper describes the development of VEPAB and summarizes the results of two experiments, one to test the sensitivity of the tasks to differences between input control devices and the other to examine practice effects.
One-Dimensional Motion Tailoring for the Disabled:A User Study
Authors: Conway Matthew , Vogtle Laura , Pausch Randy
Published: December 2015

The Tailor project allows physically disabled users to provide real-time analog input to computer applications. We use a Polhemus™ tracking device and create a custom tailored mapping from each user's best range and type of motion into the analog control signal. The application is a simple video game based on Pong, where the analog input controls the position of the player's paddle. A group of able-bodied subjects was able to correctly hit the ball with the paddle 77% of the time, and a comparison group of children with cerebral palsy performed at the 50% level. More than half the disabled users were able to perform at a higher level than the worst able-bodied user.
An Introductory Tutorial for Developing Multiuser Virtual Environments
Authors: Gossweiler Rich , Laferriere Robert J. , Keller Michael L. , Pausch Randy
Published: December 2015

This paper is an introductory level tutorial describing how to implement a distributed multiparticipant virtual environment (VE). This tutorial is intended for students who are competent programmers and who now wish to implement a distributed multiparticipant application. We describe the fundamental concepts of distributed computing for multiplayer simulations and provide a concrete example, including C source code available via the Internet. The template program demonstrates a simple multiplayer, distributed application, where each player controls the position of a space ship, and communicates the ship's position data over the network. The template uses broadcast communication and a technique called dead-reckoning to improve performance. We give detailed instructions on how to obtain and modify the template, so that students can quickly create their own distributed applications. We conclude by briefly discussing advanced issues that are important when constructing more sophisticated multiparticipant VEs.
A Distributed Virtual Reality Simulation System for Situational Training
Authors: Stansfield Sharon A.
Published: December 2015

This paper presents a laboratory review of current research being undertaken at Sandia National Laboratories in the development of a distributed virtual reality simulation system for situational training applications. An overview of the project is presented, followed by a discussion of the various components, both hardware and software. Finally, a training application being developed utilizing the system is presented.
A Quantitative Measure of Telepresence
Authors: Schloerb David W.
Published: December 2015

This paper presents the foundation for a theory of presence that seeks to answer important questions about telepresence and virtual presence. The theory, which develops the definition of telepresence to include virtual presence as a special case, permits the precise definition of various types and degrees of telepresence. General categories of telepresence are defined, using different types of presence that are proposed in the paper. Three types of specifications are used to make the definitions more precise: (1) a set of tasks, (2) a transformation imposed on the human operator's control output and sensory input, and (3) a transformation of the region of presence. The proposed quantitative measure of telepresence involves both objective and subjective measures. The degree of (objective) telepresence is equal to the probability of successfully completing a specified task. The degree of subjective telepresence is equal to the probability that a human operator perceives that he or she is physically present in a given remote environment. The measure of subjective telepresence involves a psychophysical test and is analyzed using signal detection theory. Real-world complications are addressed and a practical example of a subjective telepresence test is described.
Long-Haul Communications Support for Visualization of Computational Aeroscience Simulations
Authors: McCabe James D.
Published: December 2015

This paper discusses the long-haul data communications requirements needed to support visualization of Computational Aeroscience (CAS) simulations. A scientific computing model is presented, from which current communications requirements are derived. This model is then expanded to describe the CAS collaborative visualization environment, in which scientists from multiple NASA centers will collaborate on multidisciplinary, time-accurate simulations. An analysis of this model indicates that CAS data communications requirements will increase to 10-100 megabytes/sec by 1996.
A Window on Shared Virtual Environments
Authors: Amselem Denis
Published: December 2015

This paper presents the architecture of a multiuser distributed virtual environment (VE) software system currently used in the Virtual Perception Laboratory at the SRI International. It shows how the Linda parallel language helped in the realization of that system. An unusual interface used to fly through this shared VE is also presented: a hand-held display (HHD).
Portraying and Understanding Large-Scale Distributed Virtual Environments: Experience and Tentative Conclusions
Authors: Stytz Martin R. , Hobbs Bruce , Kunz Andrea , Soltz Brian , Wilson Kirk
Published: December 2015

The Distributed Simulation Internet (DSI) provides users access to large-scale, complex, active, unpredictable virtual environments. If users are to effectively use these environments, they will require support for understanding and acting in these environments. Support is necessary because humans have a time and space limited span of attention. The Satellite Modeler, Omniview true 3D, and Synthetic BattleBridge projects were undertaken to develop and investigate the interfaces and autonomous agents required to effectively support users of the Distributed Simulation Internet. The Satellite Modeler emulates the near-Earth space environment and portrays models of satellites moving in their correct orbits around the Earth. The motion of the satellites is broadcast to users of the DSI. The Satellite Modeler is intended to function as a training and operational aid for orbital analysts and to help them understand key spatial relationships for satellites in near-Earth orbit. The Omniview project was undertaken to provide interactive control and manipulation of a true 3D image and to thereby assist the user in understanding the activity within the DSI-hosted virtual environment. That project developed an interface that provides the Omniview user with the ease of use that a window, icon, mouse, and pointer GUI interface provides to users of 2D displays. The Synthetic BattleBridge is a system that, like the Omniview, portrays a DSI-hosted virtual environment but does not act in it. The Synthetic BattleBridge is designed to support users in making accurate and timely decisions by providing several different types of cognitive support for understanding and analyzing the activity in a battlespace. In this paper, we briefly describe each project and present some observations and conclusions we have drawn based on our experience with them.
Exploiting Position History for Efficient Remote Rendering in Networked Virtual Reality
Authors: Singhal Sandeep K. , Cheriton David R.
Published: December 2015

Distributed virtual reality systems require accurate, efficient remote rendering of animated entities in the virtual environment. Position, velocity, and acceleration information about each player is maintained at the player's local machine, but remote hosts must display this information in real-time to support interaction between users across the network. Prior applications have transmitted position information at the local frame rate, or they have relied on dead-reckoning protocols using higher derivative information to extrapolate entity position between less frequent updates. These approaches require considerable network bandwidth and at times exhibit poor behavior.

This paper describes a position history-based protocol whose update packets contain only position information. Remote hosts extrapolate from several position updates to track the location and orientation of entities between infrequent updates. Our evaluation suggests that the position history-based protocol provides a network-scalable solution for generating smooth, accurate rendering of remote entities.
Comparison of Human Sensory Capabilities with Technical Specifications of Virtual Environment Equipment
Authors: Barfield Woodrow , Hendrix Claudia , Bjorneseth Ove , Kaczmarek Kurt A. , Lotens Wouter
Published: December 2015

This paper presents the results of three surveys that compared the human's ability to detect and discriminate visual, auditory, tactile, and kinesthetic information with current technical specifications of virtual environment equipment. The comparison exposes limitations of current virtual environment interfaces and thus indicates areas where improvements in equipment design are needed. Furthermore, the paper presents basic definitions and units of measurement for sensory modalities, which also can be used to describe the capabilities of virtual environment equipment. Finally, the paper concludes with remarks concerning the relationship between the data presented in the three surveys and the design of virtual interfaces.
A Three-Dimensional Building Authoring Tool Based on Line Drawing Understanding
Authors: Ouhyoung Ming , Yan Yung-huei
Published: December 2015

Recently three-dimensional (3D) graphics has been applied in areas such as building and mechanical design, with the help of CAD tools to first construct the two-dimensional (2D) and 3D models. Building synthetic environments usually involves lots of work in constructing virtual reality worlds, and making authoring more efficient is one of the most important goals in virtual reality. We propose a prototype system that integrates several modules such as image preprocessing, vectorization, editing, and 3D model generation, to transform a 2D architecture design diagram into a 3D building model. We also propose an improved method that can efficiently recognize slant lines in addition to vertical and horizontal lines. To do this, since a line has a constant slope, we use back-tracking in our method and utilize a line slope consistency check to prune wrong targets.
Virtual Modeling of Urban Environments
Authors: Jepson William , Liggett Robin , Friedman Scott
Published: December 2015

Researchers at UCLA's Departments of Architecture and Urban Planning are using state-of-the-art visual simulation technology to build virtual worlds that can be used by planners, designers, and community groups to visualize and evaluate proposed changes and new developments in the urban environment. This paper focuses on the modeling methodology that has evolved for efficiently creating three-dimensional (3D) virtual urban worlds. It is illustrated with reference to actual projects that have recently been completed or are currently under development.
Presence within Virtual Environments as a Function of Visual Display Parameters
Authors: Hendrix Claudia , Barfield Woodrow
Published: December 2015

This paper reports the results of three studies, each of which investigated the sense of presence within virtual environments as a function of visual display parameters. These factors included the presence or absence of head tracking, the presence or absence of stereoscopic cues, and the geometric field of view used to create the visual image projected on the visual display. In each study, subjects navigated a virtual environment and completed a questionnaire designed to ascertain the level of presence experienced by the participant within the virtual world. Specifically, two aspects of presence were evaluated: (1) the sense of “being there” and (2) the fidelity of the interaction between the virtual environment participant and the virtual world. Not surprisingly, the results of the first and second study indicated that the reported level of presence was significantly higher when head tracking and stereoscopic cues were provided. The results from the third study showed that the geometric field of view used to design the visual display highly influenced the reported level of presence, with more presence associated with a 50 and 90° geometric field of view when compared to a narrower 10° geometric field of view. The results also indicated a significant positive correlation between the reported level of presence and the fidelity of the interaction between the virtual environment participant and the virtual world. Finally, it was shown that the survey questions evaluating several aspects of presence produced reliable responses across questions and studies, indicating that the questionnaire is a useful tool when evaluating presence in virtual environments.
The Sense of Presence within Auditory Virtual Environments
Authors: Hendrix Claudia , Barfield Woodrow
Published: December 2015

Two studies were performed to investigate the sense of presence within stereoscopic virtual environments as a function of the addition or absence of auditory cues. The first study examined the presence or absence of spatialized sound, while the second study compared the use of nonspatialized sound to spatialized sound. Sixteen subjects were allowed to navigate freely throughout several virtual environments and for each virtual environment, their level of presence, the virtual world realism, and interactivity between the participant and virtual environment were evaluated using survey questions. The results indicated that the addition of spatialized sound significantly increased the sense of presence but not the realism of the virtual environment. Despite this outcome, the addition of a spatialized sound source significantly increased the realism with which the subjects interacted with the sound source, and significantly increased the sense that sounds emanated from specific locations within the virtual environment. The results suggest that, in the context of a navigation task, while presence in virtual environments can be improved by the addition of auditory cues, the perceived realism of a virtual environment may be influenced more by changes in the visual rather than auditory display media. Implications of these results for presence within auditory virtual environments are discussed.
A Virtual Reality Application with Autistic Children
Authors: Strickland Dorothy
Published: December 2015

Using the advantages of the sense of presence generated by virtual reality, a system to help children with autism was developed. Two case studies with children showed virtual reality has the potential to provide a safer, customized learning environment for individuals with autism. A model of reality that discusses historical and perceptual rules as well as input stimuli in forming a sense of presence is described.
Surgical Simulation: An Emerging Technology for Training in Emergency Medicine
Authors: Delp Scott L. , Loan Peter , Basdogan Cagatay , Rosen Joseph M.
Published: December 2015

The current methods of training medical personnel to provide emergency medical care have several important shortcomings. For example, in the training of wound debridement techniques, animal models are used to gain experience treating traumatic injuries. We propose an alternative approach by creating a three-dimensional, interactive computer model of the human body that can be used within a virtual environment to learn and practice wound debridement techniques and Advanced Trauma Life Support (ATLS) procedures. As a first step, we have developed a computer model that represents the anatomy and physiology of a normal and injured lower limb. When visualized and manipulated in a virtual environment, this computer model will reduce the need for animals in the training of trauma management and potentially provide a superior training experience. This article describes the development choices that were made in implementing the preliminary system and the challenges that must be met to create an effective medical training environment.
Telerobotic Surgery Is Clinical Reality: Current Experience with Telementoring in Adults and Children
Authors: Docimo Steven G. , Moore Robert G. , Kavoussi Louis R.
Published: December 2015

A clinical telepresence surgical system was developed at The Johns Hopkins Bayview Hospital. Using both fiberoptic and coaxial cable, a control room located within the hospital was connected to the telepresence operating room. Systems allowing remote surgical teaching included continuous two-way audio communication, real-time laparoscopic and external video imaging, remote telestration, and remote control of a robotic arm designed to manipulate the laparoscope. Using this system, 27 operations were performed in adults and children under the direction of a remote surgical mentor. There were no intraoperative or postoperative complications in this series of cases. All operations were successful. Telementoring was successful in 26 of the 27 cases. In one case, poor positioning of the robotic arm was responsible for a breakdown in the remote surgical teaching process. Operative times for telepresence operations and traditionally mentored cases are compared. In summary, telementoring has proven to be a safe and potentially useful application of telerobotic surgery.
Stereoscopic Visualization in Endoscopic Surgery: Problems, Benefits, and Potentials
Authors: von Pichler Cletus , Radermacher Klaus , Boeckmann Wieland , Rau Günter , Jakse Gerhard
Published: December 2015

In recent years the application of 3D video endoscopic systems in clinical routine, especially in the field of endoscopic surgery, has increased steadily. The number of 3D video endoscopic systems used in the operating theatre today is obviously lower than the number of established traditional 2D video endoscopic systems. The hesitant application of the new technology can be mainly explained by the lack of evaluation of its influence on the surgical procedure and on patient benefit as well as by the need for specific economic analysis. The starting point for our investigations was to analyze the influence of 3D video endoscopy on endoscopically guided manipulations in general. In order to achieve quantitative statements we performed laboratory experiments using human factors analyzing methods. In the next step we performed clinical field studies of the application of 3D video endoscopic systems for a side-by-side comparison of 2D and 3D systems. These studies showed that the use of 3D video endoscopy has an improving influence on endoscopically guided surgical manipulations as well as on the intraoperative procedures. We also found that spatial visual perception of stereoscopic images of 3D video systems may cause problems for some users. For the validation of stereoscopic visualization systems we additionally studied the influence of isolated technical, optical, and physiological parameters on visual perception as well as on transposition into visually guided manipulations. Detailed results of these investigations concerning the influence of 3D video endoscopy on binocular perception are presented.
Teleos™: Development of a Software Toolkit for Authoring Virtual Medical Environments
Authors: Higgins Gerald A. , Meglan Dwight A. , Raju Rakesh , Merril Jonathan R. , Merril Gregory L.
Published: December 2015

Virtual reality simulations in medicine present a variety of technical challenges that differ from those associated with flight, space, and battlefield simulations. One imposing barrier to the widespread adoption of medical simulators is the lack of software tools that could enable medical content developers to author simulations in their respective disciplines. Our experience in developing custom standalone virtual reality applications in medicine has provided the basis for the development of Teleos™, a software toolkit for authoring interactive simulations in medicine.
Online Telecontrol Techniques Based on Object Parameter Adjusting
Authors: Slutski Leonid
Published: December 2015

An approach to telerobotic system organization with manipulator variable parameters is developed. It is intended for solution of manipulation problems when fast transportation operations are combined with high-precision positioning operations. Based on previous research, manipulator gain was chosen as a means for system quality control. It was proposed that the human operator should personally adjust the robot parameters in compliance with situation requirements. Besides such direct parameter adjustment, another implementation of this concept based on indirect adjustment (such as by analog circuit) was also developed. An additional channel of parameter control was introduced into the system in these cases. A new hand-controller design and a method for synthesis of such system algorithms were also developed. The ground has thus been laid for the kinematic coordinate-parameter control for the main regimes of telerobot work. The described approach results in the organization of effective online systems with sufficiently simple control algorithms. By means of testing, the efficiency of these systems is shown.
Effects of Image Quality, Number of Selectable Viewpoints, and Way to Select the Viewpoint in X-Ray Luggage Inspection
Authors: Pasman W. , Smets G. J. F. , Stappers P. J.
Published: December 2015

For luggage inspection, a good 3D impression is needed. This impression can be enhanced either by improving the image quality or by providing multiple viewpoints. An experiment is described in which students had to judge whether two objects in a transparent box were connected with a wire. Subjects using head movements to select the viewpoint were compared with subjects using a knob. Viewpoint selection was limited to horizontal movement. The resolution and the number of grey levels of the image as well as the size and the number of discrete steps of image movement were manipulated. Results show that 16 grey levels are sufficient to detect the wire, but that for a correct decision about connectivity, a freedom of movement of at least 90° is desirable. No difference was found between selecting the desired viewpoint with the head and by knob.
Registration Error Analysis for Augmented Reality
Authors: Holloway Richard L.
Published: December 2015

Augmented reality (AR) systems typically use see-through head-mounted displays (STHMDs) to superimpose images of computer-generated objects onto the user's view of the real environment in order to augment it with additional information. The main failing of current AR systems is that the virtual objects displayed in the STHMD appear in the wrong position relative to the real environment. This registration error has many causes: system delay, tracker error, calibration error, optical distortion, and misalignment of the model, to name only a few. Although some work has been done in the area of system calibration and error correction, very little work has been done on characterizing the nature and sensitivity of the errors that cause misregistration in AR systems. This paper presents the main results of an end-to-end error analysis of an optical STHMD-based tool for surgery planning. The analysis was done with a mathematical model of the system and the main results were checked by taking measurements on a real system under controlled circumstances. The model makes it possible to analyze the sensitivity of the system-registration error to errors in each part of the system. The major results of the analysis are: (1) Even for moderate head velocities, system delay causes more registration error than all other sources combined; (2) eye tracking is probably not necessary; (3) tracker error is a significant problem both in head tracking and in system calibration; (4) the World (or reference) coordinate system adds error and should be omitted when possible; (5) computational correction of optical distortion may introduce more delay-induced registration error than the distortion error it corrects, and (6) there are many small error sources that will make submillimeter registration almost impossible in an optical STHMD system without feedback. Although this model was developed for optical STHMDs for surgical planning, many of the results apply to other HMDs as well.
Diamond Park and Spline:Social Virtual Reality with 3D Animation, Spoken Interaction, and Runtime Extendability
Authors: Waters Richard C. , Anderson David B. , Barrus John W. , Brogan David C. , Casey Michael A. , McKeown Stephan G. , Nitta Tohei , Sterns Ilene B. , Yerazunis William S.
Published: December 2015

Diamond Park is a social virtual reality system in which multiple geographically separated users can speak to each other and participate in joint activities. The central theme of the park is cycling. Human visitors to the park are represented by 3D animated avatars and can explore a square mile of 3D terrain. In addition to human visitors, the park hosts a number of computer simulations, including tour buses and autonomous animated figures. Diamond Park is implemented using a software platform called Spline, which makes it easy to build virtual worlds where multiple people interact with each other and with computer simulations in a 3D visual and audio environment. Spline performs all the processing necessary to maintain a distributed, modifiable, and extendable model of a virtual world that is shared between the participants. For more information visit http://www.merl.com.
Health and Safety Implications of Virtual Environments: Measurement Issues
Authors: Nichols Sarah , Cobb Sue , Wilson John R.
Published: December 2015

Investigations of the potential impact of virtual environments on user health and safety require a methodological framework to identify both the effects of VE participation and the role of influential factors in causing those effects. This first in a series of 12 experiments was designed to evaluate methods, but also provided preliminary data regarding psychological and physiological effects. This discussion centers upon the value of self-reports and performance measures and the general methodological problems of evaluating participation in virtual environments.
Russula nigrovirens sp. nov. (Russulaceae) from southwestern China

Authors: Qi Zhao , Yang-Kun Li , Xue-Tai Zhu , Yong-Chang Zhao , Jun-Feng Liang
Published: December 2015

A new species, Russula nigrovirens, with phenotypic similarities to R. virescens is proposed based on morphological and molecular data. Morphologically, R. nigrovirens is characterized by the combination of non-striate pileus with dull green patches, incurved margin, non-discolouring context, globose to subellipsoid basidiospores with bluntly conical to subcylindrical warts isolated or connected with irregular lines or ridges, and large, clavate basidia. Russula nigrovirens is placed in subgenus Heterophyllidia, subsection Cyanoxanthinae.
A new species of Mongolodectes (Orthoptera: Tettigoniidae) from Alashan Plateau in China
Authors: LIU CHUN-XIANG , XU WEN-JING , ZHANG CHUN-TIAN
Published: December 2015

The genus Mongolodectes is endemic to vast Mongolian Plateau and has two recorded species in the Mongolian People’s Republic and one species in China’s Inner Mongolia. Here we describe one new species Mongolodectes huangi sp. n. from China’s Inner Mongolia. Further investigations are needed for precise identification and complete understanding on the fauna of the Mongolian Plateau.
Three new species and the first known males of the Andean spider genus
Orinomana Strand (Araneae, Uloboridae)
Authors: GRISMADO CRISTIAN J. , RUBIO GONZALO D.
Published: December 2015

Three new species of the uloborid genus Orinomana Strand, O. penelope n. sp. from Ecuador, O. viracocha n. sp. from Peru, and O. florezi n. sp. from Colombia, are described. Additionally, the male of O. ascha Grismado, from Northwestern Argentina, is described for the first time. This material includes the first males known of the genus, providing diagnostic characters for its recognition; the complex and massive embolus with several branches is proposed as a synapomorphy of the genus.
A Solar Irradiance Climate Data Record
Authors: Coddington O. , Lean J. L. , Pilewskie P. , Snow M. , Lindholm D.
Published: December 2015

We present a new climate data record for total solar irradiance and solar spectral irradiance between 1610 and the present day with associated wavelength and time-dependent uncertainties and quarterly updates. The data record, which is part of the National Oceanic and Atmospheric Administration’s (NOAA) Climate Data Record (CDR) program, provides a robust, sustainable, and scientifically defensible record of solar irradiance that is of sufficient length, consistency, and continuity for use in studies of climate variability and climate change on multiple time scales and for user groups spanning climate modeling, remote sensing, and natural resource and renewable energy industries. The data record, jointly developed by the University of Colorado’s Laboratory for Atmospheric and Space Physics (LASP) and the Naval Research Laboratory (NRL), is constructed from solar irradiance models that determine the changes with respect to quiet sun conditions when facular brightening and sunspot darkening features are present on the solar disk where the magnitude of the changes in irradiance are determined from the linear regression of a proxy magnesium (Mg) II index and sunspot area indices against the approximately decade-long solar irradiance measurements of the Solar Radiation and Climate Experiment (SORCE). To promote long-term data usage and sharing for a broad range of users, the source code, the dataset itself, and supporting documentation are archived at NOAA’s National Centers for Environmental Information (NCEI). In the future, the dataset will also be available through the LASP Interactive Solar Irradiance Data Center (LISIRD) for user-specified time periods and spectral ranges of interest.
Investigating the Effects of Subgrid Cell Dynamic Heterogeneity on the Large-Scale Modeling of Albedo in Boreal Forests*
Authors: Landry Jean-Sébastien , Ramankutty Navin , Parrott Lael
Published: December 2015

Stand-clearing disturbances, which remove most of the tree cover but are followed by forest regrowth, affect extensive areas annually, yet each event is usually much smaller than a typical grid cell in Earth system climate models. This study argues that the approach taken to account for the resulting subgrid cell dynamic heterogeneity substantially affects the computation of land–atmosphere exchanges. The authors investigated in a simplified model the effects of three such approaches on the computation of albedo over boreal forests. It was found that the simplest approach—in which any new disturbance-created patch was immediately merged with the rest of the grid cell—underestimated the annual reflected solar radiation by ~3 W m−2 on average (a relative error of 15%) compared with the most accurate approach—in which albedo computations were performed for each individual subgrid patch. This study also investigated an intermediate approach, in which each patch was tracked individually, but albedo was estimated from a much smaller number of subgrid tiles grouping patches having a similar amount of tree cover. Results from this third approach converged quickly toward the most accurate results as the number of tiles increased and were robust to changes in the thresholds used to assign patches to specific tiles. When computing time prevents implementing the most accurate approach in Earth system climate models, the results advocate for using strategies similar to the intermediate approach in order to avoid biasing the net radiative forcing of stand-clearing disturbances toward a warming impact, at least over boreal forests.
New Statistical Model for Variability of Aerosol Optical Thickness: Theory and Application to MODIS Data over Ocean*
Authors: Alexandrov Mikhail D. , Geogdzhayev Igor V. , Tsigaridis Kostas , Marshak Alexander , Levy Robert , Cairns Brian
Published: December 2015

A novel model for the variability in aerosol optical thickness (AOT) is presented. This model is based on the consideration of AOT fields as realizations of a stochastic process that is the exponent of an underlying Gaussian process with a specific autocorrelation function. In this approach, AOT fields have lognormal PDFs and structure functions with the correct asymptotic behavior at large scales. The latter is an advantage compared with fractal (scale invariant) approaches. The simple analytical form of the structure function in the proposed model facilitates its use for the parameterization of AOT statistics derived from remote sensing data. The new approach is illustrated using a 1-yr-long global MODIS AOT dataset (over ocean) with 10-km resolution. It was used to compute AOT statistics for sample cells forming a grid with 5° spacing. The observed shapes of the structure functions indicated that, in a large number of cases, the AOT variability is split into two regimes that exhibit different patterns of behavior: small-scale stationary processes and trends reflecting variations at larger scales. The small-scale patterns are suggested to be generated by local aerosols within the marine boundary layer, while the large-scale trends are indicative of elevated aerosols transported from remote continental sources. This assumption is evaluated by comparison of the geographical distributions of these patterns derived from MODIS data with those obtained from the GISS GCM. This study shows considerable potential to enhance comparisons between remote sensing datasets and climate models beyond regional mean AOTs.
A Comparison of Rhetorical Move Structure of Applied Linguistics Research Articles Published in International and National Thai Journals
Authors: Wannaruk Anchalee , Amnuai Wirada
Published: December 2015

The rhetorical organization of research articles has attracted extensive attention in genre study, and the focus of move-based analysis is on the textual function. The primary aim of the present study was the comparison of the rhetorical moves of English research articles in the field of Applied Linguistics written by Thai first authors and published in national Thai journals with those written by authors of different nationalities and published in international journals. Each of the two corpora was represented by 30 English research articles with sections of introduction, method, results and discussion. These sections were examined according to different move models: Introduction: Swales (2004), Methods: Peacock (2011), and Results and Discussion: Yang and Allison (2003). The study provided detailed rhetorical structures of research articles from both corpora with linguistic features used in each move. It was found that the frequency of rhetorical move occurrence of the two corpora was quite similar, but there were some differences in how gaps in research were established and in how credibility of the data analysis was gained. The findings of this study provide a picture of how research articles of the two corpora are written. This may lead to implications for English for Academic Purposes teachers and researchers and novice writers in Applied Linguistics.
Identifying the city center using human travel flows generated from location-based social networking data
Authors: Sun Yeran , Fan Hongchao , Li Ming , Zipf Alexander
Published: December 2015

Since cities have become more complex and some large cities are likely to be polycentric, a better understanding of cities requires a clear topology that reveals how city centers are spatially distributed and interacted with. The identification of a city center that aims to find the accurate location of the city center or delineate the city center with a precise boundary becomes vital. This work attempts to achieve this by using a new type of movement data generated from location-based social networks, whereby three different methods are deployed for clustering and compared regarding identification of city centers and delineation of their boundaries. Experiments show that city centers with precise boundaries can be identified by using the proposed approach with location-based social network data. Furthermore, the results show that the three methods for clustering have different advantages and disadvantages during the process of city center identification, and thus seem to be suitable for cities with different urban structures.
Does Sexual Orientation Precede Childhood Sexual Abuse? Childhood Gender Nonconformity as a Risk Factor and Instrumental Variable Analysis
Authors: Xu Yin , Zheng Yong
Published: December 2015

Research suggests that there is a relation between childhood sexual abuse (CSA) and adulthood nonheterosexual orientation. To explore whether nonheterosexual orientation increases the risk of CSA, we recruited a large sample, added the variable of childhood gender nonconformity (CGNC), and applied the instrumental variable method. We found that heterosexual and nonheterosexual men who were more gender nonconforming in childhood were significantly more likely to report having a history of CSA than their gender-conforming counterparts. There was no relation between CSA and CGNC for heterosexual and nonheterosexual women. The instrumental variable analysis revealed that the increased prevalence of CSA experienced by nonheterosexuals compared with heterosexuals may be due to the influence of sexual orientation on CSA. In sum, the results suggest that nonheterosexuality may increase the risk of childhood sexual abuse.
Mid-Century Cairene Movie Posters, Urban Space, and Resistance to the West
Authors: Houston Kerr
Published: December 2015

In the decade after the revolution of 1952, Egyptian films often echoed the political ideals of the new regime—and the movie posters produced in conjunction with those films sometimes embodied officially articulated attitudes toward Western influence and Egyptian history. This article considers a range of discursive strategies in examples of surviving posters produced in the 1950s and early 1960s but concentrates primarily on the representation of women in relation to public space—and it argues, ultimately, that the posters formed part of a broad attempt to define a traditionally and uniquely Egyptian public domain, in opposition to Western influence, in modern Cairo.