Designing nonperspective projection through screen-space manipulation

Projection plays an important role in our daily life as a method for expressing 3D information on 2D images. The view of each object significantly depends on how it is projected onto the 2D screen. Actually, hand drawings are distorted artificially according to the information that should be emphasized. For example, guide maps are drawn in such a way that places of interest and other landmarks are not occluded. We call such projection nonperspective projection. As a method for designing nonperspective projection, conventional researches [Takahashi et al. 2002; Singh 2002] present methods for combining the views seen from different cameras in 3D space to form a single projection. However, it is hard to estimate the change in the 2D view directly with the manipulations of cameras in 3D space and tedious trial and error processes are unavoidable. Therefore, we present a method of manipulating object views through 2D screen-space directly.