It consists of a physical three-dimensional model onto which a computer image is projected to create a realistic looking object.
Spatially augmented reality (SAR) renders virtual objects directly within or on the user's physical space.
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.
[2] Although simulated haptic feedback devices enable some aspects of computer-generated objects to be touched, they can not match this level of functionality.
Therefore, a display is needed that somehow joins the real physical world and computer-generated objects together, thus enabling them to be experienced simultaneously.
TUI systems use real physical objects to both represent and also interact with computer-generated information (Figure 1).
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[6] (Figure 1).
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.
However, head-mounted-display based systems require users to wear equipment, which limits the number of people who can simultaneously use the display.
[8] Spatially augmented reality displays project computer-generated information directly into the user's environment.
For example, the image projected onto the objects shown in Figure 3 provides colour and visual texture, which makes them appear to be made from different materials.
PA models use a unique combination of physical objects and computer-generated information, and hence they inherit advantages from both.
Instead, we walk around objects, moving in and out to zoom, gazing and focusing on interesting components, all at very high visual, spatial, and temporal fidelity”.
[10] PA models combine the high level of intuitiveness of physical models with the flexibility and functionality of computer graphics, such as the ability to be quickly altered, animated, saved and updated (Jacucci, Oulasvirta, Psik, Salovaara & Wagner, 2005).
Thus, a PA model essentially gives a physical form to a computer-generated object, which a user can touch and grasp with their bare hands.
In fact, one of the first PA model type displays was created over twenty years ago when Naimark built the ‘Displacements’ art installation (Naimark, 1984) and more recently in the “Haunted Mansion” attraction in Disney World (Liljegren & Foster, 1990).
Specifically, new technology has been developed that semi-automates the process of both creating and aligning the physical model and projected image.
Furthermore, powerful projectors (2000-3000 lumens) can be used to allow a PA model to be located in a well-lit room (Nam, 2005; Umemoro, Keller & Stappers, 2003).
However, whilst this technology enables a PA model to be a viable and useful type of display, it does not address its main aim.
However, whether or not the PA model illusion occurs is entirely dependent on a user's subjective perceptual impression.
The capabilities of the human perceptual system should guide the development of any advanced interface (Stanney et al., 2004), hence this issue needs to be addressed.
Note: Projection Augmented models are sometimes referred to as 'Shader Lamps' (Raskar, Welch, Low & Bandyopadhyay, 2001, p. 89).
Calibration Free Virtual Display System Using Video Projector onto Real Object Surface.
Psychophysically based artistic techniques for increased perceived realism of virtual environments, In Proceedings of Proceedings of the 4th International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa - AFRIGRAPH '03 (pp. 123–132).
In Proceedings Conference on Human Factors in Computer Systems - CHI’06, Workshop on “Sketching" Nurturing Creativity: Commonalities in Art, Design, Engineering and Research.
Integrating hardware and software: augmented reality based on prototyping method for digital products.
A paradigm shift in interactive computing: Deriving multimodal design principles from behavioural and neurological foundations.
The ‘Detection, Perception and Object-Presence framework’: A unified structure for investigating illusory representations of reality.