A Matching Method for 3D CAD Models with Different Assembly Structures Using Projections of Weighted Components

We present a matching method for 3D CAD assembly models consisting of multiple components. Our method discriminates not only the global shapes of the models, the numbers and kinds of their components but also the geometric layouts of the components. In order to identify the components constituting an assembly model, different numerical values such as positive integers are assigned initially to them. The same value is assigned to the same kind of components in an assembly model. However, these initially assigned values to the components vary with assembly models as often happens in practical applications. We represent an assembly model as a set of feature quantities which are computed using projections for each of the components from various angles. The similarity between two assembly models is computed from the similarities between their feature quantities. In order to make the projections reflect the layout of components in the whole assembly structure, we propose a way of reassigning numerical values to the components. This reassignment also makes the feature quantities of assembly models independent of the initially assigned values to their components. Using 3D CAD assembly models with different layouts of components, we show the effectiveness of the proposed method experimentally.