• What is field of view?
• What is field of regard?
• What does 6DOF mean?
• What is DIS?
• What is HLA?
• What is DMT?
• What is an avatar?
• What is an IOS? What features does an IOS have?
• What does force loading mean? Do I need force loading? How do I implement force loading?
• What does synergistic mean?
• What does CBI mean? How good is it?
• What does AI mean?  How good is it?
• What is an expert system? How good is it?
• What is immersion?
• What is stereoscopy/3D?
• What is fidelity?
  

What is field of view?

            Field of view (FOV) refers to the part of the head mounted display in which information is presented horizontally and vertically. The size of the FOV determines the extent to which the operator can see visual information without moving his or her head. For instance, a small FOV may only allow the operator to see a plane directly in front of him or her, as the viewing window is limited, whereas a large FOV may allow the operator to see all aspects of the scenery to the left, right, top, and bottom from his or her vantage point (Kopke, 1996). FOV’s with high resolutions enable the operator to see information in great detail, while lower resolutions provide more of a general picture of the environment. The FOV of a display is measured in terms of degrees, in that a typical FOV is 90 degrees by 120 degrees as measured from the eye of the operator (SIMTEC, 1998). Generally, head mounted displays (HMDs) provide larger fields of view then traditional panel mounted displays, and studies have indicated that larger fields of view subsequently result in enhanced performance for simulator operators (Wells & Venturino, 1990, cited in Carr & England, 1995).

            The field of regard is similar to the field of view, except that the field of regard refers to the area within which the operator can move his or her head to see visual information (SIMTEC, 1998). The field of regard is also measured in degrees, and is usually determined by tracking the eye movements of the operator. In measuring field of regard, it is important to note that the operator’s viewpoint is field of vision resulting from head movement. While the FOV is actually a component of the display, the field of regard is dependent upon the position of the operator's head. Therefore, the degree measurement of the field of regard is usually significantly smaller then the measurements associated with the operator’s FOV. In addition, a display panel on a simulator may provide a very different field of regard for the operator then the actual FOV (Kaiser, n.d.). 

             The abbreviation “DOF” refers to a measure of degrees of freedom. Degrees of freedom are a measure of variability that expresses the number of options available within space. For example, in a system with N states, the degree of freedom is N (Krippendorff, n.d.). The phrase 6 DOF is used specifically in simulation systems, referring to how many ways a rigid body can move in space. Three ways are along the linear axes: fore and aft, sideways, and up and down; while the other three ways are rotational: roll, pitch, and yaw. Six is the minimum number of degrees of freedom required to simulate the motion of a free-floating body in space (Slone, n.d.). Motion in all six DOF provides the most realistic environment within a simulation. And, logically, it follows that six restraints are needed to maintain an immobile body in space against the forces applied to it (Cappel, 1999). (Image courtesy of Mitsubishi Electronic Laboratories)

             The Distributed Interactive Simulation (DIS) concept is an infrastructure for linking simulations of various types at multiple locations. It was conceptualized by the Defense Advanced Research Projects Agency (DARPA) in 1983 to create a new technology to enable networked team training. Each simulator designed by DoD has unique differences in engineering and design, creating the challenge of coordinating simulators so they provide the same types of training despite the differences in hardware. The mission of DIS is to create "realistic, complex, virtual worlds for the simulation of highly interactive activities" (Hardt & White, 1998). Despite dissimilar technology, simulators should provide the same training to best prepare operators for future battle (Hardt & White, 1998). The best example of simulator linkage is the U.S. Army and DARPA sponsored program referred to as SIMNET.  SIMNET is a large-scale networked simulation system that links tank, helicopter, and airplane simulators, and has served as the first standard protocol for distributed interactive simulations (Rtime, n.d.).

 See also ADL
See also DMT

             The concept of the High Level Architecture (HLA) superseded the DIS standard, broadening its scope to outline a general architecture for simulation across all levels of the Department of Defense (DoD). It has been developed under the guidance of the Defense Modeling and Simulation Office (DMSO) and its concept is to promote reuse and interoperability across the large network of simulations produced and operated by DoD. It is defined by a set of rules, an interface specification, and an object model template (OMT). It offers a standardized way to define features of a simulation so they are consistently built and designed across the DoD. The technical framework of the HLA was conceptualized in 1996, adopted for use in 1998, and approved as an open standard in 2000 (DMSO, n.d.). This DoD-wide effort provides significant benefits to the modeling and simulation community in terms of increasing software reusability, reducing overall development and maintenance costs, and linking operational systems with simulations (AFRL, n.d.). Although it is necessary for interoperability across the DoD, it is not the sole solution to the current problem (SIMTEC, 1998).

  See also DIS

What is DMT?

             Distributed Mission Training (DMT) is a modeling and simulation initiative sponsored by the Air Force. It includes a series of simulations aimed at training individuals in remote locations to interact with a variety of realistic threats. These threats include other entities and environments, and could consist of both trainees in simulators and realistic computer representations. As the Air Force initiative evolves, more interactive simulations will be included in Air Force training procedures and such simulations will be more likely to include elements such as virtual representations of airborne command and control systems, tankers, and even unmanned air vehicles. Recently, the Air Force demonstrated the operability of four aircraft simulators at the same time, allowing them to connect and communicate with one another (Norman, 2000). With the user of advanced simulations to support the DMT concept, it is believed that the Air Force and other Services will achieve superior mission training (SIMTEC, 1998).

 See also DIS
See also Cost Effectiveness of DMT

What is an avatar?

             An avatar is an abstract representation of the user in a virtual world. It is a living entity within a simulation, and can be classified into two different groups. Player characters (PCs) are avatars that are typically played by living, human beings and are the primary representation of living participants within the simulation. Non-player characters (NPCs) are avatars are not consistently played by humans, and are generally used to provide supporting roles for stories as they unfold within the simulation (VRML, 1997). 

See also Missing Team Members  

What is an IOS? What features should an IOS have?

            An Instructor/Operator Station (IOS) is a method for providing instructor input into the training device. An IOS supports many training modes, from individualized training to large networked exercises. An IOS provides the instructor with a means to monitor the student's performance and to control the different levels of simulation encountered by the student during the training session. An IOS may provide complete control of the scenario by the instructor, or it may also run in an autonomous mode where it fully controls and manages the scenario at hand. For an effective training environment utilizing the concept of DMT and interoperability of simulations, an IOS will need to function at all levels of the simulation (SIMTEC, 1998).

            In training devices, an IOS should have certain characteristics. For example, an IOS will need adequate controls and displays designed for performance monitoring. Interface features that optimize the ease of use for the instructor include windows, colors, icons, merged text, and graphics. The display should be a complete representation of the battlespace, or a "god's eye view" in order for the operator to perform the necessary functions associated with the mission. In terms of assisting the instructor in the control of the simulation, the IOS should also provide for introduction of malfunctions, abnormal conditions, environmental changes, and threat activity into the scenario (SIMTEC, 1998).

 See also DMT

What does force loading mean? Do I need force loading? How do I implement force loading?

              In an aircraft, a pilot experiences a constant variety of forces on his or her body. Pilots receive auditory, visual, and physical cues, consciously and unconsciously, from these forces about the accelerations of the aircraft. Cues from within are referred to as proprioception and arise from vestibular and kinesthetic stimulation. The vestibular system is sensitive to gravity and linear movement of the head, while the kinesthetic system is aware of the orientation and the rates of movement of different parts of the body resulting from stimulation to the joints, muscles, and tendons. In addition, auditory cues are picked up by the ears and allow the pilot to perceive forces associated with the aircraft such and engine vibration and deployment of weapons. Motion can also be perceived visually, without true movement, in what is referred to as vection. The pilot can construe motion simply by examining the changes in the visual scene, regardless of inputs to the vestibular and kinestetic systems (SIMTEC, 1998).

            Recreating force cueing in simulations, also referred to as force loading, is very important. Static simulators fail to recreate these cues. However, simulators with force cueing devices such as platform motion, dynamic seat, or g-suit, do attempt to simulate such forces and provide a more realistic experience for the operator.  In addition, studies of simulators with force cueing devices indicated that simulating these cues does affect operator control and performance, and that operators feel that they are in a more realistic scenario when such cues are present (SIMTEC, 1998). However, it should be emphasized to designers of simulators that requirements for force cueing must be implemented properly in order to improve performance. Poorly designed hardware and software and inaccurate algorithms used to determine the forces necessary can contribute to a less realistic simulator with a greater likelihood of initiating simulator sickness and motion sickness symptoms (SIMTEC, 1998).

            There are a variety of means of implementing force cueing devices into simulations. The most common force cueing device is platform motion, which is the only device that provides the operator with vestibular cues. However, implementing platform motion is very expensive. The dynamic seat may be an alternative to platform motion, as it applies forces to the body by inflation and deflation of the seat and other forms of seat movement. Although it does not provide vestibular cues, it does provide realistic kinesthetic and disturbance cues such as turbulence. Other force cueing devices include an anti-g suit, mimicking high g-forces, helmet loader, providing forces through the helmet, and Combat edge, providing a positive pressure breathing system. Although this is not an exhaustive list of force cueing devices, such devices are the most commonly used in commercial and military simulators today (SIMTEC, 1998).

 See also Motion
See also Simulator Sickness

What does synergistic mean?

            The term synergy is used to describe the operation of the two entities in tangent with one another. Ideas used synergistically, for example, allow each idea or concept to offer strengths to the other to produce more accurate and insightful recommendations (Baker & Grabau, 1998). Synergy in reference to simulations refers to a state where the "whole" is greater then the sum of all of the "parts". For example, a simulation with many different modes such as visual, auditory, and vestibular stimulation can have synergistic effects on the overall success and realism of the simulator when used for training (Baligko, Hirst, & Shein, n.d.).

 See also Fidelity
See also Immersion

What is CBI? How good is it?

            Computer-Based Instruction (CBI), also referred to as Computer-Based Training (CBT), is a method by which computers are used to deliver training in particular knowledge or skill. CBIs vary in their sophistication of presentation, in that older training modules consist of text-based instruction on a computer monitor, while new CBIs incorporate virtual reality, sound cards, and powerful graphics. They also vary in the amount of interaction between the user and the CBI, in that one with little interactivity presents material in a predetermined sequence, while a highly interactive CBI allows the learner almost complete control over what is studied. CBIs also vary in their fidelity of instruction, or the degree to which the lesson simulates the environment where the skill must actually be applied (Weiss & Craiger, 1997).

            CBIs offer numerous features and benefits to learners and to organizations. They provide individualized instruction to students who can learn at their own pace. They also encourage active and interactive learning that often does not occur in the classroom, and they adjust difficulty levels to suit students' needs. Similarly, the computer also provides immediate feedback to learners about their progress. For organizations, CBIs reduce training time in comparison to traditional classroom instruction, and they also reduce expenses associated with training new employees. However, CBIs also have significant drawbacks. For example, developing a CBI is time-consuming and expensive. In addition, a CBI must be constantly maintained in order to supply up-to-date information for learners. Finally, CBIs are often considered inflexible, in that they only provide a few methods of communication (keyboard, mouse, and touchpad) to the learner, and learners anticipated responses must already be programmed into the system (Eberts & Brock, 1988, cited in Weiss & Craiger, 1997). 

 See also Blended Learning

What does AI mean? How good is it?

             Artificial Intelligence (AI) is the study of how computer systems can simulate the intelligence of human beings. Processes such as learning, reasoning, and understanding symbolic information can be mimicked by computer systems, producing output identical to what would have been generated by the human mind. AI is not solely the development of computer systems. AI is used to study and understand human intelligence, as there are still many unknowns about the human brain. Human problem solving is goal directed, and computers can be taught not only to solve a problem but also to recognize patterns in problem solving and apply these methods to the tackling of new challenges in a similar goal directed manner (Newell & Simon, 1972). Current AI research strives to develop computers that can plan ahead and take on a broader perspective (Minsky, 1982). In simulations, AI is commonly used to help develop and understand computer vision, or the presentation of information in a three-dimensional format. There are currently limited ways of representing three-dimensional objects in simulation, and AI offers insight into the visual inputs associated with learning, reasoning, and decision-making (Anonymous, n.d.).

See also Expert Systems

What is an expert system? How good is it?

             The application of artificial intelligence to systems that simulate the specialized skills held by experts in a given area or specialty is known as an expert system. The problems solved by expert systems would normally require human intelligence, but advanced technology has allowed computers to store and apply this knowledge. An incredible feature of expert systems is their ability to learn, or adjust, to new scenarios. For example, if an expert system solves one problem using a preprogrammed strategy, but then a slightly different problem is presented, the system can apply the strategy and adjust it to fit the new problem. In this sense, expert systems are considered to be machines capable of learning (PC AI, n.d.).

            One of the earliest expert systems, called Mycin, was developed at Stanford University in the 1970s and used to diagnose and recommend treatment for blood disorders. Mycin’s design has strongly influenced the present day design of commercial and military expert systems (Herriott-Watt University, n.d). Although expert systems provide the advantages of storing knowledge infinitely in a computer and continuing to add to this knowledge through learning capabilities, they also present challenges to developers of the systems. In general, human experts find it difficult to describe their own expertise, as much of their knowledge becomes intuitive after time. Experts often cannot explicitly state their knowledge, or the rules that guide their performance. Developers of expert systems must often interrogate experts to collect the necessary information. As a result, many expert systems may not adequately reflect the actual implicit and procedural knowledge retained by human beings (Anonymous, n.d.).

                                     See also AI

What is immersion?

            Immersion is a state in which the operator of the simulator feels so a part of the environment that they exclude their immediate reality. In training, learners who are immersed “develop the subjective impression that they are participating in a ‘world’ comprehensive and realistic enough to induce the willing suspension of disbelief” (Dede, Salzman, & Loftin, 1996). Immersion is directly related to the feeling of telepresence, or actually "being there" when in a virtual environment (VE). Telepresence is considered an experience, and has been hypothesized to contribute to performance enhancements when used for training (Whitmer & Singer, 1994). In a study performed using immersive and non-immersive devices, researchers discovered that subjects had enhanced searching skills in immersive environments and concluded that immersive environments were more usable than non-immersive environments (Boyd, 1997). In addition, immersion has also been linked to degree of control. Subjects reported a greater sense of presence when they had higher degrees of control over what objects they could examine and how they could maneuver in a VE (Bangay & Preston, n.d.).

            Immersive VE systems are usually equipped with a head mounted display (HMD), or a helmet that holds the visual and auditory displays. In order to create a fully immersive environment, the field of view should extend to peripheral vision (Taylor, 1997). This will allow a vivid display at all possible moments, reducing the feeling that the user is actually sitting in a room with an HMD on. In addition, many researchers suggest that language should be eliminated at this state in the VE. In an ideal VE, the user should be able to grab and move objects, mold them through a touch of their hand, and change their color with a virtual brush. The user should not feel an overwhelming need to speak or communicate, as the VE should provide an opportunity to communicate visually, through the mind (Ryan, 1994). (Image Courtesy of SGI Courtesy of SGI Japan, Ltd)

See also Fidelity
See also Fidelity and Training Effectiveness

What is stereoscopy/3D?

             Stereoscopic displays are devices that reproduce the way we see three-dimensional space by providing a unique image for each eye. The science of stereoscopy is used primarily to enhance the ability of humans to make depth judgements (Anonymous, 1998). The actual process consists of the two images being displayed sequentially, with LCD shutter glasses used to shut off the alternate eyes in order to enable synchronization with the display. When the brain receives the images in rapid succession, it merges the two images into a single scene and allows depth to be perceived. With traditional stereoscopic displays, it is imperative that a fairly high display swapping rate be used to avoid flicker. Any sense of flicker will disturb the VE for the operator and result in degradations in telepresence and realism. A more advanced stereoscopic system is called a head-mounted display (HMD), and can be created by positioning small display screens in front of each eye. HMDs are equipped with special optics which stretch the perceived field of view for added realism (Isdale, 1993).

 See also Binocular Visual Displays
See also Visual Perception

 What is fidelity?

             Fidelity is the degree of realism in a simulation. Fidelity is also referred to as telepresence, or the extent to which the user feels mentally present in the virtual environment. Telepresence can be achieved by providing an accurate representation of objects, events, and people which look, feel, and sound real (Lombard & Ditton, 1997). Simulation designers can achieve telepresence by manipulated viewing angle, display area, viewing distance, dimensionality, image size, degree of motion, head movement, and display lag to simulate a realistic experience. Telepresence can be measured by the amount of senses receiving input (sight, sound, touch etc) coupled with the degree to which the current physical environment is blocked out of the user's mind (Kim, 1996). Also, specially designed telepresence questionnaires for the operator are administered after exposure to the virtual environment. When a simulation fully immerses its users in the virtual environment, it is said to have high fidelity. The physiological effects of high fidelity simulations include arousal, vection (sense of self-motion), and illusory sensations of climbing and turning. Users may also later experience reduced hand-eye coordination and motion sickness (Azar, 1996). (Image courtesy of Silicon Graphics Computer Systems).

See also Immersion
See also Simulator Sickness