Modeling Objects and Environments

McIntosh, in ACADIA Newsletter Vol. 9 No. 3 pp 20-23, June 1990. This book introduces the concept of modelling objects in the computer's memory so it can be used to aide the process of their design. Modelling is defined as an hierarchical abstraction of data and operators to manipulate it, subject to semantic integrity constraints that guarantee the realizability of the designed artifact in the real world. Starting with general concepts of modelling, the book moves on to discuss the modelling of shapes (form) in two and in three dimensions. The discussion covers both topology and geometry. Next the book introduces the concept of shape transformations (translation, scaling, rotation, etc.), both in absolute and in relative terms. The book then introduces the concept of assembly modelling, and adds non-graphical attributes to the representation. It concludes with a discussion on user interface and parametrization. The book includes many examples written in Pascal that complement the theory, and can be used as a basis for building a geometric modelling engine. It also includes exercises, so it can be used as a text book for a two-semester advance course in geometric modellin