3D screen-space widgets for non-linear projection

Abstract

Figure 1: Defining a nonlinear projection of a 3D scene. Left: Original scene from a default view showing sketched 3D features. Right: The new, nonlinear projection. Two curve constraints are used to bow the side walls, and a point constraint is used to warp the back wall. A bstractLinear 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.

Perceptually-Guided Design of Nonperspectives through Pictorial Depth Cues

“…Deforming the target 3D objects allows us to simulate the effect of composing nonperspective images as seen from multiple viewpoints [9], [10], [11]. 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].…”

“…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.…”

Non-linear perspective widgets for creating multiple-view images

“…An attractive method for defining cameras is to use image-space constraints [Blinn 1988;Gleicher and Witkin 1992;Coleman et al 2005]. Unfortunately, it can be difficult to control the camera in this manner because the solver is not guaranteed to produce a meaningful solution.…”

RTcams: A New Perspective on Nonphotorealistic Rendering from Photographs

“…They too use the idea of a master camera [16]. More recently, they provide widgets to assist user interaction [17].…”