Features in Layered Manufacturing of Heterogeneous Objects

The usage of features in computer aided design and manufacturing has increased significantly over the last decade. By and large, all such features are geometric (form features). In this paper, we shall discuss the need to go beyond current geometric features and consider material -- composition, and gradation -- within the object. This need has been brought about by layered manufacturing technologies which build up parts, layer by layer, under computer control. While industrial use of this new technology has been for making prototypes, functional metallic parts can/are being made by layered manufacturing. Furthermore, a variety of materials can be deposited to create multi-material and functionally graded components. We consider features in this new domain (of layered manufacturing) and identify research topics and present an overview of our current focus on "material features" in the context of heterogeneous solid models.