scholarly journals A New Calibration Process for a Homogeneous Cyclorama Illumination in Virtual TV Sets

2019 ◽  
Vol 9 (10) ◽  
pp. 2020 ◽  
Author(s):  
Roi Méndez ◽  
Enrique Castelló ◽  
José Ramón Ríos Viqueira ◽  
Julián Flores
Keyword(s):  
Virtual Environments ◽  
Real Time ◽  
Virtual Environment ◽  
Computer System ◽  
Visual Information ◽  
Statistical Study ◽  
Statistical Data ◽  
Calibration Process ◽  
Background Removal ◽  
Custom Software

A virtual TV set combines actors and objects with computer-generated virtual environments in real time. Nowadays, this technology is widely used in television broadcasts and cinema productions. A virtual TV set consists of three main elements: the stage, the computer-system and the chroma-keyer. The stage is composed by a monochrome cyclorama (the background) in front of which actors and objects are located (the foreground). The computer-system generates the virtual elements that will form the virtual environment. The chroma-keyer combines the elements in the foreground with the computer-generated environments by erasing the monochrome background and insetting the synthetic elements using the chroma-keying technique. In order to ease the background removal, the cyclorama illumination must be diffuse and homogeneous, avoiding the hue differences that are introduced by shadows, shines and over-lighted areas. The analysis of this illumination is usually performed manually by an expert using a photometer which makes the process slow, tedious and dependent on the experience of the operator. In this paper, a new calibration process to check and improve the homogeneity of a cyclorama’s illumination by non-experts using a custom software which provides both visual information and statistical data, is presented. This calibration process segments a cyclorama image in regions with similar luminance and calculates the centroid of each of them. The statistical study of the variation in the size of the regions and the position of the centroids are the key tools used to determine the homogeneity of the cyclorama lighting.

Integrated Real-Time Calibration of Electromagnetic Tracking of User Motions for Engineering Applications in Virtual Environments

2002 ◽  
Vol 124 (4) ◽  
pp. 623-632 ◽  
Author(s):  
Uma Jayaram ◽  
Roglenda Repp
Keyword(s):  
Virtual Environments ◽  
Real Time ◽  
Virtual Environment ◽  
Physical World ◽  
Electromagnetic Tracking ◽  
Tracking Systems ◽  
Calibration System ◽  
Time Calibration ◽  
Calibration Accuracy ◽  
Mathematical Techniques

A real-time integrated calibration system for virtual reality environments has been developed that enables accurate electromagnetic tracking of user motions. Electromagnetic tracking systems suffer degradation in accuracy due to the presence of metals and other electromagnetic distortions in the environment. Calibration of the virtual environment to account for these distortions is essential for VR applications in engineering where correlation between the virtual environment and the physical world is important. The major contribution of the paper is the presentation of a comprehensive methodology for calibrating the VR space, the numerical/mathematical techniques proposed for the calibration, and case studies for calibration accuracy and execution time to enable using these techniques in real time in an integrated setup.

Presence in Text-Based Networked Virtual Environments or “MUDS”

1997 ◽  
Vol 6 (5) ◽  
pp. 590-595 ◽  
Author(s):  
John Towell ◽  
Elizabeth Towell
Keyword(s):  
Social Interaction ◽  
Virtual Environments ◽  
Real Time ◽  
Virtual Environment ◽  
Networked Virtual Environments ◽  
Sense Of Presence ◽  
Networked Virtual Environment ◽  
Being There ◽  
Anecdotal Information

A text-based networked virtual environment represents to a user a system of rooms joined by exits and entrances. When navigating this system of rooms, a user can communicate in real time with other connected users occupying the same room. Hence, these virtual environments are aptly suited for networked conferencing and teaching. Anecdotal information suggested that some people feel a sense of “being there” or presence when connected to one of these environments. To determine how many people feel this sense of presence, we surveyed 207 people from 6 different groups of users of text-based networked virtual environments. The results indicated that 69% of these subjects felt a sense of presence. Experiments with people in text-based networked virtual environments may be helpful in understanding the contribution to presence by social interaction in other virtual environments.

Study on Level-of-Detail for Behavior of Real-Time Virtual Environments

2014 ◽  
Vol 926-930 ◽  
pp. 2118-2121
Author(s):  
Yong Dan Nie ◽  
Yan Zhang ◽  
Xian Mei Liu
Keyword(s):  
Virtual Environments ◽  
Real Time ◽  
Virtual Environment ◽  
Large Scale ◽  
Level Of Detail ◽  
Virtual Scene ◽  
New Methods ◽  
Level Of Details ◽  
Different Levels

This article based on the level of details (LOD) technology of current geometry layer research, introduced the thinking of technology into the behavior layer of virtual environment characters rendering, as the basis from the important level of the characters and the characters of their location, used different levels of details on the rendering of characters, made a balance between characters rendering time and characters facility and reduced the rendering time of large-scale virtual scene, made an increase the number of virtual scene characters with new methods.

Integrating Sounds and Motions in Virtual Environments

1998 ◽  
Vol 7 (1) ◽  
pp. 67-77 ◽  
Author(s):  
James K. Hahn ◽  
Hesham Fouad ◽  
Larry Gritz ◽  
Jong Won Lee
Keyword(s):  
Genetic Algorithms ◽  
Conceptual Framework ◽  
Virtual Environments ◽  
Real Time ◽  
Virtual Environment ◽  
Integrated System ◽  
Present System ◽  
Virtual Objects ◽  
Functional Representation

Sounds are often the result of motions of virtual objects in a virtual environment. Therefore, sounds and the motions that caused them should be treated in an integrated way. When sounds and motions do not have the proper correspondence, the resultant confusion can lessen the effects of each. In this paper, we present an integrated system for modeling, synchronizing, and rendering sounds for virtual environments. The key idea of the system is the use of a functional representation of sounds, called timbre trees. This representation is used to model sounds that are parameterizable. These parameters can then be mapped to the parameters associated with the motions of objects in the environment. This mapping allows the correspondence of motions and sounds in the environment. Representing arbitrary sounds using timbre trees is a difficult process that we do not address in this paper. We describe approaches for creating some timbre trees including the use of genetic algorithms. Rendering the sounds in an aural environment is achieved by attaching special environmental nodes that represent the attenuation and delay as well as the listener effects to the timbre trees. These trees are then evaluated to generate the sounds. The system that we describe runs parallel in real time on an eight-processor SGI Onyx. We see the main contribution of the present system as a conceptual framework on which to consider the sound and motion in an integrated virtual environment.

scholarly journals Comparing and Evaluating Real Time Character Engines for Virtual Environments

2010 ◽  
Vol 19 (2) ◽  
pp. 95-117 ◽  
Author(s):  
Marco Gillies ◽  
Bernhard Spanlang
Keyword(s):  
Open Source ◽  
Virtual Environments ◽  
Real Time ◽  
Virtual Environment ◽  
State Of The Art ◽  
The State ◽  
Animated Characters

As animated characters increasingly become vital parts of virtual environments, then the engines that drive these characters increasingly become vital parts of virtual environment software. This paper gives an overview of the state of the art in character engines, and proposes a taxonomy of the features that are commonly found in them. This taxonomy can be used as a tool for comparison and evaluation of different engines. In order to demonstrate this we use it to compare three engines. The first is Cal3D, the most commonly used open source engine. We also introduce two engines created by the authors, Piavca and HALCA. The paper ends with a brief discussion of some other popular engines.

Some Recent Results in Quiescent Prominence Spectrometry

1979 ◽  
Vol 44 ◽  
pp. 41-47
Author(s):  
Donald A. Landman
Keyword(s):  
Real Time ◽  
Computer System ◽  
Spectral Response ◽  
Absolute Intensity ◽  
Solar Observatory ◽  
Target Size ◽  
Small Target ◽  
Signal Averaging ◽  
Quiescent Prominence

This paper describes some recent results of our quiescent prominence spectrometry program at the Mees Solar Observatory on Haleakala. The observations were made with the 25 cm coronagraph/coudé spectrograph system using a silicon vidicon detector. This detector consists of 500 contiguous channels covering approximately 6 or 80 Å, depending on the grating used. The instrument is interfaced to the Observatory’s PDP 11/45 computer system, and has the important advantages of wide spectral response, linearity and signal-averaging with real-time display. Its principal drawback is the relatively small target size. For the present work, the aperture was about 3″ × 5″. Absolute intensity calibrations were made by measuring quiet regions near sun center.

Remote real-time computer system for medical research and diagnosis

JAMA ◽  
1966 ◽  
Vol 196 (11) ◽  
pp. 967-972
Author(s):  
J. F. Dickson
Keyword(s):  
Medical Research ◽  
Real Time ◽  
Computer System

scholarly journals Perceptual uncertainty and action consequences independently affect hand movements in a virtual environment

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Martin Giesel ◽  
Anna Nowakowska ◽  
Julie M. Harris ◽  
Constanze Hesse
Keyword(s):  
Virtual Environments ◽  
Virtual Environment ◽  
Motor Skills ◽  
Hand Movements ◽  
Perceptual Information ◽  
Avoidance Task ◽  
Natural Environments ◽  
Motor Behaviour ◽  
Virtual And Augmented Reality

AbstractWhen we use virtual and augmented reality (VR/AR) environments to investigate behaviour or train motor skills, we expect that the insights or skills acquired in VR/AR transfer to real-world settings. Motor behaviour is strongly influenced by perceptual uncertainty and the expected consequences of actions. VR/AR differ in both of these aspects from natural environments. Perceptual information in VR/AR is less reliable than in natural environments, and the knowledge of acting in a virtual environment might modulate our expectations of action consequences. Using mirror reflections to create a virtual environment free of perceptual artefacts, we show that hand movements in an obstacle avoidance task systematically differed between real and virtual obstacles and that these behavioural differences occurred independent of the quality of the available perceptual information. This suggests that even when perceptual correspondence between natural and virtual environments is achieved, action correspondence does not necessarily follow due to the disparity in the expected consequences of actions in the two environments.

Dropouts and Aftereffects: Examining General Accessibility to Virtual Environment Technology

2002 ◽  
Vol 46 (26) ◽  
pp. 2114-2118 ◽  
Author(s):  
Kay M. Stanney ◽  
Kelly S. Kingdon ◽  
Robert S. Kennedy
Keyword(s):  
Virtual Environments ◽  
Virtual Environment ◽  
Broad Spectrum ◽  
General Public ◽  
Dropout Rates ◽  
Environment Exposure ◽  
Oculomotor Disturbances ◽  
A Minor

Are current virtual environments (VEs) usable by the broad spectrum of people who may wish to utilize this technology? The current study, which examined over 1000 participants, indicates the answer to this question is a definitive ‘no’. Virtual environment exposure was found to cause people to vomit (1.1%), experience nausea (71%), disorientation (70%), and oculomotor disturbances (79%). Overall, 88% of participants reported some level of adverse symptomatology, ranging from a minor headache to vomiting and intense vertigo. These disturbances led 12% of those exposed to prematurely cease their interaction. Dropout rates as high as nearly 50% were found in exposures of 1 hr in length. In addition, long-term aftereffects were found, including headaches, drowsiness, nausea, and fatigue. These problems could substantially reduce the accessibility of VE technology by the general public and thus must be resolved if this technology is to be widely adopted.

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