1. List different components of virtual reality system ?Essentially, virtual reality systems consist of the computer and software—known as thereality engine—input sensors, and output sensors. The input sensors are the equipment tocomputer enthusiasts, and include the keyboard, mouse, knobs, and joysticks. Outputdevices include the printer and the video display monitor. In addition, virtual reality inputand output devices include the head- and ear-mounted equipment mentioned above, andgloves for controlling the virtual world. Finally, the fourth sensory component is the user,who both directs and reacts to the chosen environment.Virtual reality is an artificial environment that is created and maintained by a computerand that is at least partly shaped and determined by the user. A virtual reality systemallows the user to "leave" the real world and step into a world whose sensory inputs(sights, sounds, smells, etc.) are provided not by natural objects but by computer-createdmeans. The things that happen in that virtual world can then be manipulated to a largeextent by the user.ComponentsIn its most basic form, virtual reality systems consist of a computer and software—knownas the reality engine—and input and output sensors. A sensor is a device that responds tosome physical stimulus. A human eye, for example, is a sensor that responds to light rays.In standard computer technology, input devices are the familiar keyboard, mouse, knobs,and joysticks; output devices include the printer and video display. Virtual realityinput/output devices include head- and earmounted equipment for hearing and seeing andgloves for controlling the virtual world. The fourth "component" is the user, who directsthe chosen environment and reacts to it.The reality engine. The reality engine employs both computer hardware and software tocreate the virtual world. Reality engines are based largely on the same components thatmake up a personal computer (PC), although much more computing power is required forthe reality engine than is available in a standard PC.One key to virtual reality is creating a world that appears real. The images created by thecomputer and software are extremely complex compared to the relatively simple line-based graphics associated with computer games. Virtual reality images are made withtiny dotlike segments of a picture known as pixels, or picture elements. Each pixel itselfis made up of hundreds of thousands of dots. The more pixels there are per inch, thebetter or more realistic the image will be.
Words to KnowCathode-ray tube (CRT): A form of vacuum tube in which a beam of electrons isprojected onto a screen covered with a fluorescent material in order to produce a visiblepicture.Ergonomics: The study of the way humans and objects interact with each other.Haptic: Relating to the sense of touch.Light-emitting diode (LED): A device made of semiconducting materials that emitslight when an electric current is applied to it.Liquid crystal display (LCD): A way of displaying visual information by using liquidcrystals that emit light when exposed to electric current.Pixel: One of the small individual elements of which a visual image consists.Reality engine: The hardware and software used in virtual reality systems.Virtual: Something that is representative or the essence of a thing but not the actualthing.Creating realistic images that can be manipulated is known as realization. These imagescan be either opaque, in which all the viewer sees is the virtual world, or see-through, inwhich the virtual image is projected or superimposed onto the outer world.Sound enriches the virtual world. The experience of soaring through the air in a simulatedcockpit is more realistic if the user hears the roar of the engines. Sound also enhancesparticipation in the virtual world by providing the user with audio cues. For example, theuser may be directed to look for the virtual airplane flying overhead.To incorporate the total experience, the reality engine also may use haptic enhancement.Haptic experiences are those that involve the participants senses of touch and pressure.Haptic cues, however, are complex and expensive and have been used primarily formilitary and research applications.Headsets. Head-mounted display (HMD) units use a small screen or screens (one foreach eye) that are worn in a helmet or a pair glasses. Unlike a movie, where the directorcontrols what the viewer sees, the HMD allows viewers to look at an image from variousangles or change their field of view by simply moving their heads.HMD units usually employ cathode-ray tube (CRT) or liquid crystal display (LCD)technology. CRTs incorporate optic systems that reflect an image onto the viewers eye.Although more bulky and heavy than LCD displays, CRT systems create images thathave extremely high resolutions, making a scene seem that much more realistic. In
addition, CRT images can be semireflective, allowing the viewer to see the outside worldas well. Such units have practical applications since the user can operate a machine orother device while viewing the virtual world.Although LCD technology has lagged behind CRT in picture quality, LCD systems areslimmer, lighter, and less expensive, making them better suited for home use. These unitsuse liquid crystal monitors to display two slightly different images that the brainprocesses into a single three-dimensional view. Initial efforts to market this technology tohome users failed because of poor LCD image quality. But rapid advances in LCDtechnology have improved the images, and higher quality LCD-based units have becomeavailable for home use.Audio units. Sound effects in virtual reality rely on a prerecorded sound set that isdifficult to alter once the reality engine begins to generate audio. The audio portion ofvirtual reality is transmitted through small speakers placed over each ear. Audio cues mayinclude voices, singing, the sound of bubbling water, thudlike noises of colliding objects—in short, any sound that can be recorded.Three-dimensional (or omnidirectional) sound further enhances the virtual realityexperience. Sounds that seem to come from above, below, or either side provide audiocues that mimic how sounds are heard in the real world. Three-dimensional sound isachieved through the use of highly complex filtering devices. This technology must takeinto account factors like interaural time difference (which ear hears the sound first) andinteraural amplitude difference (which ear hears the sound louder). The most complexhuman hearing dynamic is called head-related transfer functions (HRTF). HRTF accountsfor how the eardrum and inner ear process sound waves, taking into consideration thevarious frequencies at which these waves travel as well as how waves are absorbed andreflected by other objects. HRTF audio processing enables the listener not only to locatea sound source but also to focus in on a specific sound out of a multitude of sounds, likedistinguishing the call of a hot dog vendor out of a noisy crowd at a baseball game.Gloves. Gloves in virtual reality allow the user to interact with the virtual world. Forexample, the user may pick up a virtual block, turn it over in a virtual hand, and set it ona virtual table. Wired with thin fiberoptic cables, some gloves use light-emitting diodes(LEDs) to detect the amount of light passing through the cable in relation to themovement of the hand or joint. The computer then analyzes the correspondinginformation and projects this moving hand into the virtual reality. Magnetic trackingsystems also are used to determine where the hand is in space in relation to the virtualscene.Some gloves use haptic enhancement to provide a sense of touch and feel. In hapticenhancement, the reality engine outputs the tactile experience, which may include force,heat, and texture. Tactile experiences are created by remeasuring a pattern of forces,which is programmed into the reality engine and then relayed back to the user when theappropriate object is touched. Virtual reality gloves may use either air pressure (such asstrategically placed inflated air pockets in the glove) or vibrating transducers placed next
to the skin (such as a voice coil from a stereo speaker or alloys that change shape throughthe conduction of electrical currents) to simulate tactile experience.Tools under development. Many other virtual reality tools are in the phases of researchand development. Remote control robotic or manipulator haptic devices are being testedfor industry and medicine. Special wands with sensors, joysticks, and finger sensors suchas picks and rings will eventually be as common to virtual reality technology asmicrowaves are to cooking. The technology to control the virtual world through voicecommands also is rapidly advancing.Perhaps the most impressive technology under development is the whole body suit. Thesesuits would function similarly to the gloves, creating a virtual body that could take a strollthrough a virtual world and feel a virtual windstorm.Read more: Virtual Reality - humans, body, used, water, process, form, system, air,effects, waves, basic, change, Components, Applicationshttp://www.scienceclarified.com/Ti-Vi/Virtual-Reality.html#ixzz18UVukCZI3. What is Graphics Tablets? What is advantage of using themas input device?Ans. A graphics tablet (or digitizer, digitizing tablet, graphics pad, drawing tablet) isa computer input device that allows one to hand-draw images and graphics, similar to theway one draws images with a pencil and paper. These tablets may also be used to capturedata or handwritten signatures. It can also be used to trace an image from a piece of paperwhich is taped or otherwise secured to the surface. Capturing data in this way, either bytracing or entering the corners of linear poly-lines or shapes is called digitizing.A graphics tablet (also called pen pad or digitizer) consists of a flat surface upon whichthe user may "draw" or trace an image using an attached stylus, a pen-like drawingapparatus. The image generally does not appear on the tablet itself but, rather, isdisplayed on the computer monitor. Some tablets, however, come as a functioningsecondary computer screen that you can interact with images directly by using the stylus.A graphics tablet is an input device used by artists which allows one to draw a pictureonto a computer screen without having to utilize a mouse or keyboard. A graphics tabletconsists of a flat tablet and some sort of drawing device, usually either a pen or stylus. Agraphics tablet may also be referred to as a drawing tablet or drawing pad. While thegraphics tablet is most suited for artists and those who want the natural feel of a pen-likeobject to manipulate the cursor on their screen, non-artists may find them useful as well.The smooth flow of a graphics tablet can be refreshing for those who find the mouse to
be a jerky input device, and repetitive stress injuries such as carpal tunnel syndrome areless likely when using a graphics tablet.4. Explain different area filling techniques.In an all-points-addressable (APA) graphics display, a hardware area fill technique forclipped graphics objects is described which allows graphics objects to be area filled bysimple hardware at high speed, even when part of the object is clipped off by a screen orviewport boundary. Hardware registers defining X and Y coordinates of screen pels(picture elements) include additional bits to define off-screen space. Logic is provided toprevent drawing in off-screen space and automatically to complete the boundaries beforefilling. An APA graphics system normally consists of a number of memory arrays (bitplanes), each having one addressable location per screen pixel. Most of these planes areusually used to define the colour of the pixels, but often one is reserved for use whendrawing area-filled (Image Omitted) objects.5. What is homogenous co-ordinate system? How does it differfrom Cartesian system?homogeneous coordinates, are a system of coordinates used in projective geometrymuch as Cartesian coordinates are used in Euclidean geometry. They have the advantagethat the coordinates of a point, even those at infinity, can be represented using finitecoordinates. Often formulas involving homogeneous coordinates are simpler and moresymmetric than their Cartesian counterparts. Homogeneous coordinates have a range ofapplications, including computer graphics and 3D computer vision, where they allowaffine transformations and, in general, projective transformations to be easily representedby a matrix.If the homogeneous coordinates of a point are multiplied by a non-zero scalar then theresulting coordinates represent the same point. An additional condition must be added onthe coordinates to ensure that only one set of coordinates corresponds to a given point, sothe number of coordinates required is, in general, one more than the dimension of theprojective space being considered. For example, two homogeneous coordinates arerequired to specify a point on the projective line and three homogeneous coordinates arerequired to specify a point on the projective plane.