Abstract: Composition is an important aspect of both traditional illustration practices and non-photorealistic rendering methods. Composition means combining drawing elements such as line, tone, texture, focus of attention and arranging them in order, to make one cohesive unit. In this paper we present commonly used terms for drawing composition, present important key principles (unit, balance, center of interest, emphasis), and discuss how such principles are used to precisely convey the information to be depicted, with images embodying rich aesthetic qualities. We present two NPR experiments illustrating compositional principles and aesthetical implications in the context of line rendering of single 3D objects and global illumination mesh interior models