“Designing Nonperspective Projection through Image-Space Manipulation”

Perspective projection is a primary projection technique in the area of 3D computer graphics. On the other hand, hand-drawn illustrations are usually drawn using nonperspective projection techniques where the images are synthesized by composing multiple views each of which is seen from its own viewpoint. This paper presents a new approach for intuitively editing nonperspective images through screen space manipulations. The present approach allows us to embed different views into a single image by taking advantage of a grid of 3D camera parameter samples as the underlying data structure. In addition, a set of design operations are implemented so that the users can arbitrarily modify the 3D camera parameter field by the direct control of corresponding 2D views on the screen. Several design examples are demonstrated so that our approach allows us to transform an ordinary perspective image into a nonperspective one for simulating a given 2D hand-drawn picture.