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Plant ware devices peripheral computing complexes and electronic digital machines

Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. The computer technology that allows us to develop three-dimensional virtual environments VEs consists of both hardware and software. The current popular, technical, and scientific interest in VEs is inspired, in large part, by the advent and availability of increasingly powerful and affordable visually oriented, interactive, graphical display systems and techniques.

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Introduction to Computer Information Systems/Print version

Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. The computer technology that allows us to develop three-dimensional virtual environments VEs consists of both hardware and software. The current popular, technical, and scientific interest in VEs is inspired, in large part, by the advent and availability of increasingly powerful and affordable visually oriented, interactive, graphical display systems and techniques.

Graphical image generation and display capabilities that were not previously widely available are now found on the desktops of many professionals and are finding their way into the home. The greater affordability and availability of these systems, coupled with more capable, single-person-oriented viewing and control devices e. Limiting VE technology to primarily visual interactions, however, simply defines the technology as a more personal and affordable variant of classical military and commercial graphical simulation technology.

A much more interesting, and potentially useful, way to view VEs is as a significant subset of multimodal user interfaces. Multimodal user interfaces are simply human-machine interfaces that actively or purposefully use interaction and display techniques in multiple sensory modalities e. In this sense, VEs can be viewed as multimodal user interfaces that are interactive and spatially oriented.

The human-machine interface hardware that includes visual and auditory displays as well as tracking and haptic interface devices is covered in Chapters.

In this chapter, we focus on the computer technology for the generation of VEs. One possible organization of the computer technology for VEs is to decompose it into functional blocks. In Figure , three distinct classes of blocks are shown: 1 rendering hardware and software for driving modality-specific display devices; 2 hardware and software for modality-specific aspects of models and the generation of corresponding display representations; 3 the core hardware and software in which modality-independent aspects of models as well as consistency and registration among multimodal models are taken into consideration.

Beginning from left to right, human sensorimotor systems, such as eyes, ears, touch, and speech, are connected to the computer through human-machine interface devices. These devices generate output to, or receive input from, the human as a function of sensory modal drivers or renderers.

The auditory display driver, for example, generates an appropriate waveform based on an acoustic simulation of the VE.

To generate the sensory output, a computer must simulate the VE for that particular sensory mode. For example, a haptic display may require a physical simulation that includes.

An acoustic display may require sound models based on impact, vibration, friction, fluid flow, etc. Each sensory modality requires a simulation tailored to its particular output. Next, a unified representation is necessary to coordinate individual sensory models and to synchronize output for each sensory driver. This representation must account for all human participants in the VE, as well as all autonomous internal entities.

Finally, gathered and computed information must be summarized and broadcast over the network in order to maintain a consistent distributed simulated environment. To date much of the design emphasis in VE systems has been dictated by the constraints imposed by generating the visual scene.

The nonvisual modalities have been relegated to special-purpose peripheral devices. Similarly, this chapter is primarily concerned with the visual domain, and material on other modalities can be found in Chapters 3 - 7. However, many of the issues involved in the modeling and generation of acoustic and haptic images are similar to the visual domain; the implementation requirements for interacting, navigating, and communicating in a virtual world are common to all modalities.

Such multimodal issues will no doubt tend to be merged into a more unitary computational system as the technology advances over time. In this section, we focus on the computer technology for the generation of VEs. The computer hardware used to develop three-dimensional VEs includes high-performance workstations with special components for multisensory displays, parallel processors for the rapid computation of world models, and high-speed computer networks for transferring information among participants in the VE.

The implementation of the virtual world is accomplished with software for interaction, navigation, modeling geometric, physical, and behavioral , communication, and hypermedia integration. Control devices and head-mounted displays are covered elsewhere in this report.

VE requires high frame rates and fast response because of its inherently interactive nature. The concept of frame rate comes from motion picture technology. In a motion picture presentation, each frame is really a still photograph.

If a new photograph replaces the older images in quick succession, the illusion of motion in engendered. The update rate is defined to be the rate at which display changes are made and shown on the screen. In keeping with the original motion picture technology, the ideal update rate is 20 frames new pictures per second or higher. The minimum acceptable rate for VE is lower, reflecting the trade-offs between cost and such tolerances.

With regard to computer hardware, there are several senses of frame rate: they are roughly classified as graphical, computational, and data access. Graphical frame rates are critical in order to sustain the illusion of presence. Note that these frame rates may be independent: the graphical scene may change without a new computation and data access due to the motion of the user's point of view.

Experience has shown that, whereas the graphical frame rate should be as high as possible, frame rates of lower than 10 frames per second severely degrade the illusion of presence. If the graphics being displayed relies on computation or data access, then computation and data access frame rates of 8 to 10 frames per second are necessary to sustain the visual illusion that the user is watching the time evolution of the VE.

Fast response times are required if the application allows interactive control. It is well known Sheridan and Ferrell, that long response times also called lag or pure delay severely degrade user performance. These delays arise in the computer system from such factors as data access time, computation time, and rendering time, as well as from delays in processing data from the input devices.

As in the case of frame rates, the sources of delay are classified into data access, computation, and graphical categories. Although delays are clearly related to frame rates, they are not the same: a system may have a high frame rate, but the image being displayed or the computational result being presented may be several frames old.

Research has shown that delays of longer than a few milliseconds can measurably impact user performance, whereas delays of longer than a tenth of a second can have a severe impact. The frame rate and delay required to create a measurable impact will in general depend on the nature of the environment.

Relatively static environments with slowly moving objects are usable with frame rates as low as 8 to 10 per s and delays of up to 0. In all cases, however, if the frame rate falls below 8 frames per s, the sense of an animated three-dimensional environment begins to fail, and if delays become greater than 0. We summarize these results to the following constraints on the performance of a VE system:. Both the graphics animation and the reaction of the environment to user actions require extensive data management, computation, graphics, and network resources.

All operations that take place to support the environment must operate within the above time constraints. Although one can imagine a system that would have the graphics, computation, and communications capability to handle all environments, such a system is beyond current technology. For a long time to come, the technology necessary.

Real-world simulation applications will be highly bound by the graphics and network protocols and by consistency issues; information visualization and scientific visualization applications will be bound by the computational performance and will involve issues of massive data management Bryson and Levit, ; Ellis et al.

Some applications, such as architectural visualization, will require photorealistic rendering; others, such as information display, will not. Thus the particular hardware and software required for VE implementation will depend on the application domain targeted.

There are some commonalities of hardware and software requirements, and it is those commonalities on which we focus in our examination of the state of the art of computer hardware and software for the construction of real-time, three-dimensional virtual environments.

The ubiquity of computer graphics workstations capable of real-time, three-dimensional display at high frame rates is probably the key development behind the current push for VEs today. We have had flight simulators with significant graphics capability for years, but they have been expensive and not widely available. Even worse, they have not been readily programmable.

Flight simulators are generally constructed with a specific purpose in mind, such as providing training for a particular military plane. Such simulators are microcoded and programmed in assembly language to reduce the total number of graphics and central processing unit cycles required. Systems programmed in this manner are difficult to change and maintain. Hardware upgrades for such systems are usually major undertakings with a small customer base. An even larger problem is that the software and hardware developed for such systems are generally proprietary, thus limiting the availability of the technology.

The graphics workstation in the last 5 years has begun to supplant the special-purpose hardware of the flight simulator, and it has provided an entry pathway to the large numbers of people interested in developing three-dimensional VEs. The following section is a survey of computer graphics workstations and graphics hardware that are part of the VE development effort. Graphics performance is difficult to measure because of the widely varying complexity of visual scenes and the different hardware and software approaches to computing and displaying visual imagery.

The most. Polygons are the most common building blocks for creating a graphic image. It has been said that visual reality is 80 million polygons per picture Catmull et al. There is no current graphics hardware that provides this, so we must make approximations at the moment.

This means living with less detailed virtual worlds, perhaps via judicious use of hierarchical data structures see the software section below or off-loading some of the graphics requirements by utilizing available CPU resources instead.

For the foreseeable future, multiple processor workstations will be playing a role in off-loading graphics processing. Moreover, the world modeling components, the communications components, and the other software components for creating virtual worlds also require significant CPU capacity. While we focus on graphics initially, it is important to note that it is the way world modeling effects picture change that is of ultimate importance. This section describes the high-level computer architecture issues that determine the applicability of a graphics system to VE rendering.

Two assumptions are made about the systems included in our discussion. First, they use a z-buffer or depth buffer , for hidden surface elimination. A z-buffer stores the depth—or distance from the eye point—of the closest surface ''seen" at that pixel. When a new surface is scan converted, the depth at each pixel is computed.

If the new depth at a given pixel is closer to the eye point than the depth currently stored in the z-buffer at that pixel, then the new depth and intensity information are written into both the z-buffer and the frame buffer.

Otherwise, the new information is discarded and the next pixel is examined. In this way, nearer objects always overwrite more distant objects, and when every object has been scan converted, all surfaces have been correctly ordered in depth.

The second assumption for these graphic systems is that they use an application-programmable, general-purpose processor to cull the database. The result is to provide the rendering hardware with only the graphics primitives that are within the viewing volume a perspective pyramid or parallel piped for perspective and parallel projections respectively.

Both of these assumptions are valid for commercial graphics workstations and for the systems that have been designed by researchers at the University of North Carolina at Chapel Hill. Per-primitive operations are those that are performed on the points, lines, and triangles that are presented to the rendering system.

These include transformation of vertices from object coordinates to world, eye, view volume, and eventually to window coordinates, lighting calculations at each vertex, and clipping to the visible viewing volume.

Rasterization is the process of converting the window-coordinate primitives to fragments corresponding to the pixels held in the frame buffer. The frame buffer is a dedicated block of memory that holds intensity and other information for every pixel on the display surface. The frame buffer is scanned repeatedly by the display hardware to generate visual imagery. Each of the fragments includes x and y window coordinates, a color, and a depth for use with the z-buffer for hidden surface elimination.

In computing , firmware [a] is a specific class of computer software that provides the low-level control for the device's specific hardware. Firmware can either provide a standardized operating environment for the device's more complex software allowing more hardware-independence , or, for less complex devices, act as the device's complete operating system , performing all control, monitoring and data manipulation functions.

Hardware is the most visible part of any information system: the equipment such as computers, scanners and printers that is used to capture data, transform it and present it to the user as output. Although we will focus mainly on the personal computer PC and the peripheral devices that are commonly used with it, the same principles apply to the complete range of computers:. And we are already moving into the age of wearable computers for medical or security applications, embedded computers in appliances ranging from motor cars to washing machines, and the smart card which will provide identification, banking facilities, medical records and more! Data may enter an information system in a variety of different ways, and the input device that is most appropriate will usually depend on the type of data being entered into the system, how frequently this is done, and who is responsible for the activity. For example, it would be more efficient to scan a page of typed text into an information system rather than retyping it, but if this happens very seldom, and if typing staff are readily available, then the cost of the scanner might not be justified. However, all of the input devices described in this chapter have at least one thing in common: the ability to translate non-digital data types such as text, sound or graphics into digital i.

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Today's world runs on computers. Nearly every aspect of modern life involves computers in some form or fashion. As technology is advancing, the scale of computer use is increasing. Computer users include both corporate companies and individuals. Computers are efficient and reliable; they ease people's onerous jobs through software and applications specific to their needs offering convenience. Moreover, computers allow users to generate correct information quickly, hold the information so it is available at any time.

В тот же миг шелест генераторов перешел в рев, потрясший корабль - звук, вдвойне впечатляющий, ибо Элвин впервые слышал протестующий крик машин. И на этом все закончилось; в ушах, казалось, звенела тишина. Огромные генераторы сделали свое дело; до конца путешествия они не понадобятся. Звезды впереди вспыхнули сине-белым огнем и исчезли в ультрафиолете. Но благодаря какому-то чуду науки или природы Семь Солнц оставались видны по-прежнему, хотя их расположение и цвета несколько изменились.

Он не нашел других выходов, хотя изучил тысячу коридоров и десять тысяч пустых помещений.

Неведомый механизм, управлявший этими образами, контролировался, надо полагать, самим присутствием Олвина и, до некоторой степени, его мыслями. Когда он входил в это помещение, зеркала вначале всегда были слепы, но стоило ему только начать двигаться, как они тотчас же наполнялись Было похоже, что он стоит в каком-то просторном открытом дворе, которого он никогда прежде не видел, но который, вполне вероятно, и впрямь сушествовал где-нибудь в Диаспаре.

Двор этот был необычно многолюден, похоже, что здесь происходило какое-то собрание. На приподнятой платформе двое мужчин вели вежливый спор, а их сторонники стояли внизу и время от времени бросали спорящим реплики. Полнейшая тишина лишь добавляла очарования происходящему: воображение немедленно принялось восполнять отсутствующие звуки. 0 чем они спорят. -- думал Олвин.

Из-за этого, а также в силу свойственного ему упрямства и чувства независимости, Олвину не слишком хотелось обращаться к Хедрону -- разве что в самом крайнем случае. Они договорились встретиться в маленьком круглом дворике неподалеку от Зала Совета.

В городе было множество таких вот уединенных местечек частенько расположенных всего в нескольких шагах от оживленной магистрали, но совершенно изолированных от людской толчеи. Добраться до них, как правило, можно было только пешком, изрядно побродив сначала вокруг да около.

По мере того как существо все более и более охотно отвечало на вопросы Хилвара, его внешний вид начал меняться. Оно сползло обратно в озеро, и его ноги-чурбачки, казалось, растворились в теле.

Внезапно произошла вещь еще более невероятная: три огромных глаза медленно закрылись, стянулись в крохотные точки и бесследно исчезли.

Он просто проплывет сквозь это наваждение, пробуя его на вкус, пока не проснется в городе, который ему хорошо знаком. Он направлялся в самое сердце Диаспара, к той его точке, где в его эпоху будет стоять усыпальница Ярлана Зея. Теперь, в этом древнем городе, здесь ничего еще не было, стояло только низкое, круглое здание, в которое вело множество сводчатых дверей. Около одной из них его дожидался какой-то Джизираку следовало бы онеметь от изумления, но теперь его уже ничто не могло удивить.

Почему-то это казалось совершенно правильным и естественным -- оказаться лицом к лицу с человеком, построившим Диаспар. Полагаю, вы меня узнали,-- обратился к нему Ярлан Зей. -- Ну. Ведь я тысячи раз видел ваше изображение. Вы -- Ярлан Зей, а это все -- Диаспар, каким он был миллиард лет. Я понимаю, что все это мне снится и что ни вас, ни меня в действительности здесь .

Nov 26, - focuses on processing, whereas a variety of peripheral devices facilitate input, output, storage A mainframe computer is an advanced multiuser machine typically used to manage A CPU is a complex integration of millions of transistors the digital bits through an electronic bus, stores the instruction in.

Таково, по крайней мере, было первое влечатление. Секундой позже за этими пристально глядяшими на него глазами он рассмотрел очертания небольшой, но,по-видимому, очень сложной машины. Она висела в воздухе в нескольких футах над поверхностью земли и ничем не напоминала ни одного из тех роботов, которые когда-либо встречались Олвину. Когда первоначальное изумление прошло, он вполне почувствовал себя хозяином положения.

Всю жизнь он отдавал приказания машинам, и то, что эта вот была ему незнакома, не имело ни малейшего значения. В конце концов, ему приходилось сталкиваться не более чем с несколькими процентами всех разновидностей роботов, которые в Диаспаре обслуживали его повседневные Ты умеешь говорить. -- спросил. Ответом было молчание.

Но они не вернулись - а это было так. - Может быть, они передумали. Странно, подумал Элвин: и он, и Хилвар стали бессознательно употреблять слово "они". Кем бы или чем бы "они" ни были - их влияние сильно ощущалось на первой из планет, а здесь - еще сильнее. Это был мир, тщательно упакованный и отложенный в сторону, до востребования. - Давай вернемся на корабль, - задыхаясь, вымолвил Элвин.

- Я не могу здесь нормально дышать. Как только воздушный шлюз закрылся, они, придя немного в себя, стали обсуждать следующие шаги. Для надлежащего исследования необходимо было проверить как можно больше куполов в надежде отыскать незаблокированный, в который можно было бы войти. Если из этого ничего не выйдет.

У поверхности воды плавали крошечные полупрозрачные колокольчики с почти невидимыми щупальцами. Вытянув руку, Элвин коснулся одного из них - и тут же бросил, сердито вскрикнув.

И вот сейчас одну из этим способностей я и хочу использовать. Гляди.

К этим стенам, к сокрытой в них мощи некогда подступили и сотрясли их силы, способные обращать в пыль целые миры - и потерпели полное поражение. Некогда эти мирные небеса пылали огнем, вырванным из солнечных сердец, и перед яростью своих властелинов, как живые, дрожали горы Лиса.

Никто и никогда не смог захватить Шалмирану.

Рецепторы Изображения оказались закрыты. -- Не понимаю,-- бросил Олвин, забыв в эти мгновения, что робот способен действовать только по прямому указанию к отвечать только строго в рамках заданного ему вопроса. Он быстро поправился: -- Чем закрыты. -- Мне неизвестно.

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