hancock-carpendale - Supporting Multiple Off-Axis...

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Unformatted text preview: Supporting Multiple Off-Axis Viewpoints at a Tabletop Display Mark Hancock, Sheelagh Carpendale University of Calgary Calgary, AB, Canada { msh,sheelagh } @cs.ucalgary.ca Abstract A growing body of research is investigating the use of tabletop displays, in particular to support collaborative work. People often interact directly with these displays, typ- ically with a stylus or touch. The current common focus of limiting interaction to 2D prevents people from perform- ing actions familiar to them in the 3D world, including pil- ing, flipping and stacking. However, a problem arises when viewing 3D on large displays that are intended for proximal use; the view angle can be extremely oblique and lead to distortion in the perception of the 3D projection. We present a simplified model that compensates for off-axis viewing for a single user and extend this technique for multiple view- ers interacting with the same large display. We describe several implications of our approach to collaborative ac- tivities. We also describe other display configurations for which our technique may prove useful, including proximal use of a wall or multiple-display configurations. 1. Introduction Interest in supporting co-located collaboration via table- top displays has been growing rapidly. Interaction with these large displays is often provided through direct-touch or stylus input. When people use this form of interaction, we necessarily expect that they will use these displays from a very close distance. This close distance implies that the viewing angle is likely to be severely off-axis. For example, with a tabletop display the traditional viewpoint is centred directly above the screen. For normal viewing from any side of the table, one’s viewpoint is extremely off-axis or skewed . This skew has already been shown to be problematic for per- ception of lengths in 2D interfaces on tabletop displays [19]. In 3D interfaces, the problem of off-axis viewing is exacer- bated. The use of standard projection techniques (perspec- tive and orthographic) may result in significant distortion when objects are viewed from off-axis (see Figure 1). Despite the potential difficulties, there are several rea- sons to think that incorporating 3D into large-display inter- faces would be beneficial. We all make good use of the third dimension in the physical world: we make stacks, Figure 1. (left) Standard perspective projec- tion, (right) compensated for the appropri- ate off-axis viewpoint. Both photographs are taken from the viewpoint of a person at one side of the table 1 . piles and looser groupings, and turn items over and use their other side. The need to support these types of information- handling functionalities has been well discussed [1, 9, 17]....
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This note was uploaded on 02/13/2012 for the course CS 91.550 taught by Professor Yanco during the Spring '11 term at UMass Lowell.

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hancock-carpendale - Supporting Multiple Off-Axis...

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