Conference Paper

3D screen-space widgets for non-linear projection

DOI: 10.1145/1101389.1101433 Conference: Proceedings of the 3rd International Conference on Computer Graphics and Interactive Techniques in Australasia and Southeast Asia 2005, Dunedin, New Zealand, November 29 - December 2, 2005
Source: DBLP


Linear perspective is a good approximation to the format in which the human visual system conveys 3D scene information to the brain. Artists expressing 3D scenes, however, create nonlinear projections that balance their linear perspective view of a scene with elements of aesthetic style, layout and relative importance of scene objects. Manipulating the many parameters of a linear perspective camera to achieve a desired view is not easy. Controlling and combining multiple such cameras to specify a nonlinear projection is an even more cumbersome task. This paper presents a direct interface, where an artist manipulates in 2D the desired projection of a few features of the 3D scene. The features represent a rich set of constraints which define the overall projection of the 3D scene. Desirable properties of local linear perspective and global scene coherence drive a heuristic algorithm that attempts to interactively satisfy the given constraints as a weight-averaged projection of a minimal set of linear perspective cameras. This paper shows that 2D feature constraints are a direct and effective approach to control both the 2D layout of scene objects and the conceptually complex, high dimensional parameter space of nonlinear scene projection.

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    • "The CRC provides specific solutions to the problems of combining two or more viewpoints, of how to modify the camera model in real time to track a target, and of how to disocclude a path. One method of addressing the challenge of specifying the nonlinear projection that achieves a desired artistic [22] or disocclusion [23] effect is based on widgets, which are image regions where special projection rules apply. The projection of a widget is specified as one of several predefined projections or it is computed from a set of user specified constraints. "
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    • "Projection with multiple cameras is an effective approach for generating nonperspective images [12], [13], [14]. which was followed by an interactive interface that directly manipulates 2D image deformations [14]. Our approach related to the last category, while the associated image deformation is rather automated because we take full advantage of the perceptual tolerance of nonperspective deformation in terms of the configuration of pictorial perspective cues. "
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    • "In computer graphics, much work on camera planning (see recent surveys [15] [5]) is script-based [16], purely reactive [17] [6] (whose time horizon equals one), or mostly focuses on problems with predefined target trajectories [18] [19] [20] [21] [22] [23] [24]. Many of these methods are based on constraint solving, objective satisfaction or both. "
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