|
A projection augmented model (PA model) is an element sometimes employed in virtual reality systems. It consists of a physical three-dimensional model onto which a computer image is projected to create a realistic looking object. Importantly, the physical model is the same geometric shape as the object that the PA model depicts. ==Uniting physical and virtual objects== Spatially augmented reality (SAR) renders virtual objects directly within or on the user's physical space.〔()〕 A key benefit of SAR is that the user does not need to wear a head-mounted display. Instead, with the use of spatial displays, wide field of view and possibly high-resolution images of virtual objects can be integrated directly into the environment. For example, the virtual objects can be realized by using digital light projectors to paint 2D/3D imagery onto real surfaces, or by using built-in flat panel displays. Real objects can be physically handled and naturally manipulated to be viewed from any direction, which is essential for ergonomic evaluation and provides a strong sense of palpability.〔Ishii & Ullmer, 1997.〕 Although simulated haptic feedback devices enable some aspects of computer-generated objects to be touched, they can not match this level of functionality.〔Evans, Wallace, Cheshire & Sener, 2005; Baradaran & Stuerzlinger, 2005; Khoudja, Hafez & Kheddar, 2004〕 It is, therefore, unsurprising that physical objects are still used for many applications, such as product design.〔Dutson & Wood, 2005.〕 However, computer-generated objects have a key advantage; they provide a level of flexibility that cannot be matched by physical objects. Therefore, a display is needed that somehow joins the real physical world and computer-generated objects together, thus enabling them to be experienced simultaneously.〔Gibson, Gao & Campbell, 2004; Ishii & Ullmer, 1997.〕 Tangible user interfaces (TUI) and augmented reality both aim to address this issue. TUI systems use real physical objects to both represent and also interact with computer-generated information (Figure 1). However, while TUIs create a physical link between real and computer-generated objects, they do not create the illusion that the computer-generated objects are actually in a user’s real environment. That is the aim of augmented reality. ''Figure 1 Continuum of advanced computer interfaces, based on Milgram and Kishino (1994). '' Unlike virtual reality (VR), which immerses a user in a computer-generated environment, augmented reality (AR) joins together physical and virtual spaces by creating the illusion that computer-generated objects are actually real objects in a user’s environment〔Azuma et al., 2001〕 (Figure 1). Furthermore, head-mounted-display based AR and VR systems can directly incorporate physical objects. Thus, as a user reaches out to a computer-generated object that they can see, they touch an equivalent physical model that is placed at the same spatial location.〔Whitton, Lok, Insko & Brooks, 2005; Billingshurst, Grasset & Looser, 2005; Borst & Volz, 2005; Lee, Chen, Kim, Han & Pan, 2004; Hoffman, Garcia-Palacios, Carlin, Furness & Botella-Arbona, 2003.〕 Such systems enable the computer-generated visual appearance of the object to be dynamically altered, while the physical model provides haptic feedback for the object’s underlying form. However, head-mounted-display based systems require users to wear equipment, which limits the number of people who can simultaneously use the display. A variant of the AR paradigm that does not suffer from these limitations is spatially augmented reality (Figure 1).〔Raskar, Welch, Fuchs, 1998.〕 Spatially augmented reality displays project computer-generated information directly into the user’s environment.〔Bimber & Raskar, 2005.〕 Although there are several possible display configurations, the most natural type is the projection augmented model. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Projection augmented model」の詳細全文を読む スポンサード リンク
|