Matching Free-form Primitives with 3D Medical Data to Represent Organs and Anatomical Structures

Three-dimensional representations of organs and anatomical structures can be derived from sets of two-dimensional data (images) in different ways. Most approaches are based on the use of voxels (to provide digital representations of volumes) or triangles (to sample surfaces that interpolate sets of contours). The approach we have developed is different: it is basically interactive and thus it takes advantage of user’s expertise to define specific and highly-structured geometrical models of organs. The first problem is to define free-form primitives as basic components for the creation of three-dimensional models. The second problem is to make these primitives match as well as possible with actual data: an interactive procedure enables the user to roughly position the primitive onto the data; then, an automatic process selects the relevant data and optimizes the shape of the primitive. In this paper, we describe this interactive approach and the problems it raises; then, we focus on the description of an original solution to optimize the shape of free-form primitives through actual data.