Augmented Reality: A class of displays on the reality-virtuality ...
Augmented Reality: A class of displays on the reality-virtuality ...
Augmented Reality: A class of displays on the reality-virtuality ...
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provide effective c<strong>on</strong>formal overlays, for example, a significant amount <str<strong>on</strong>g>of</str<strong>on</strong>g> world knowledge is necessary,which would also move Class 3 rightwards in <strong>the</strong> figure.5.2 Reproducti<strong>on</strong> FidelityThe remaining two dimensi<strong>on</strong>s also deal with <strong>the</strong> issue <str<strong>on</strong>g>of</str<strong>on</strong>g> realism in MR <str<strong>on</strong>g>displays</str<strong>on</strong>g>, but in different ways: interms <str<strong>on</strong>g>of</str<strong>on</strong>g> image quality and in terms <str<strong>on</strong>g>of</str<strong>on</strong>g> immersi<strong>on</strong>, or presence, within <strong>the</strong> display. It is interesting to notethat this approach is somewhat different from those taken by o<strong>the</strong>rs. Both Sheridan's 31 and Robinett's 33tax<strong>on</strong>omies, for example, focus <strong>on</strong> <strong>the</strong> feeling <str<strong>on</strong>g>of</str<strong>on</strong>g> presence as <strong>the</strong> ultimate goal. This is c<strong>on</strong>sistent as wellwith <strong>the</strong> progressi<strong>on</strong> in "realspace imaging" technology outlined in Naimark's tax<strong>on</strong>omy 3 , towardsincreasingly more realistic <str<strong>on</strong>g>displays</str<strong>on</strong>g> which eventually make <strong>on</strong>e feel that <strong>on</strong>e is participating in "unmediated<strong>reality</strong>". In our tax<strong>on</strong>omy we purposely separate <strong>the</strong>se two dimensi<strong>on</strong>s, however, in recogniti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong>practical usefulness <str<strong>on</strong>g>of</str<strong>on</strong>g> some high quality visual <str<strong>on</strong>g>displays</str<strong>on</strong>g> which never<strong>the</strong>less do not attempt to make <strong>on</strong>e feelwithin <strong>the</strong> remote envir<strong>on</strong>ment (e.g. Class 1), as well as some see-through display situati<strong>on</strong>s in which <strong>the</strong>viewer in fact is already physically immersed within <strong>the</strong> actual real envir<strong>on</strong>ment but may be provided with<strong>on</strong>ly relatively low quality graphical aids (e.g. Classes 3 and 4).C<strong>on</strong>venti<strong>on</strong>al(M<strong>on</strong>oscopic)Video4 1 2 5 6 7 3HighColour Stereoscopic Definiti<strong>on</strong>Video3D HDTVVideoVideoSimpleWireframesVisibleSurfaceImagingShading,Texture,TransparencyRayTracing,RadiosityReproducti<strong>on</strong> Fidelity (RF)Real-time,Hi-fidelity,3D Animati<strong>on</strong>:PhotorealismFigure 3: Reproducti<strong>on</strong> Fidelity (RF) dimensi<strong>on</strong>.The elements <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Reproducti<strong>on</strong> Fidelity (RF) dimensi<strong>on</strong> are illustrated in Fig. 3. The term "Reproducti<strong>on</strong>Fidelity" refers to <strong>the</strong> relative quality with which <strong>the</strong> syn<strong>the</strong>sising display is able to reproduce <strong>the</strong> actual orintended images <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> objects being displayed. It is important to point out that this figure is actually a grosssimplificati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> a complex topic, and in fact lumps toge<strong>the</strong>r several <str<strong>on</strong>g>class</str<strong>on</strong>g>es <str<strong>on</strong>g>of</str<strong>on</strong>g> factors, such as displayhardware, signal processing and graphic rendering techniques, etc., each <str<strong>on</strong>g>of</str<strong>on</strong>g> which could in turn be brokendown into its own tax<strong>on</strong>omic elements.In terms <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> present discussi<strong>on</strong>, it is important to realise that <strong>the</strong> RF dimensi<strong>on</strong> pertains to reproducti<strong>on</strong>fidelity <str<strong>on</strong>g>of</str<strong>on</strong>g> both real and virtual objects. The reas<strong>on</strong> for this is not <strong>on</strong>ly because many <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> hardwareissues, such as display definiti<strong>on</strong>, are related. Even though <strong>the</strong> simplest graphic <str<strong>on</strong>g>displays</str<strong>on</strong>g> <str<strong>on</strong>g>of</str<strong>on</strong>g> virtual objectsand <strong>the</strong> most basic video images <str<strong>on</strong>g>of</str<strong>on</strong>g> real objects are quite distinct, <strong>the</strong> c<strong>on</strong>verse is not true for <strong>the</strong> highfidelity extremum. In Fig. 3 <strong>the</strong> ordering above <strong>the</strong> axis is meant to show a rough progressi<strong>on</strong>, mainly inhardware, <str<strong>on</strong>g>of</str<strong>on</strong>g> video reproducti<strong>on</strong> technology. Below <strong>the</strong> axis <strong>the</strong> progressi<strong>on</strong> is towards more and moresophisticated computer graphic modelling and rendering techniques. At <strong>the</strong> right hand side <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> figure, <strong>the</strong>'ultimate' video display, denoted here as 3D HDTV, might be just as close in quality as <strong>the</strong> 'ultimate'graphic rendering, denoted here as "real-time, hi-fidelity 3D animati<strong>on</strong>", both <str<strong>on</strong>g>of</str<strong>on</strong>g> which approachphotorealism, or even direct viewing <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> real world.The importance <str<strong>on</strong>g>of</str<strong>on</strong>g> Reproducti<strong>on</strong> Fidelity for <strong>the</strong> MR tax<strong>on</strong>omy goes bey<strong>on</strong>d having world knowledge for<strong>the</strong> purpose <str<strong>on</strong>g>of</str<strong>on</strong>g> superimposing modelled data <strong>on</strong>to unmodelled data images, or vice versa, as discussed289 / SPIE Vol. 2351, Telemanipulator and Telepresence Technologies (1994)