Criteria for Orthographic Viewpoints

Although there is growing consensus on the need to move to comprehensive, view-based approaches to software engineering, there is much less consensus on what views and viewpoints should be used to do this and what relationship they should have to the system being viewed. One approach that aims to provide a simple yet powerful approach to view-based software engineering is the orthographic modeling approach inspired by the orthographic projection technique used in CAD systems. However, the criteria that a set of views and viewpoints should fulfill to be regarded as orthographic have never been clearly defined. Nor have the criteria that a set of dimensions should fulfill in order to be regarded as orthogonal. In this paper we aim to take some initial steps towards defining such criteria. After first identifying some of the main weaknesses in existing view-based modeling approaches we provide an overview of orthographic modeling and clarify some of the principles that underpin it.