A method for modeling an object, particularly suited to complex objects such as anatomical objects, and manipulating the modeled object in a CAD environment includes obtaining volumetric scan data of a region and segmenting the scan data to identify a first object to produce a first set of signed distance values on a grid. Wavelet analysis of the first set of signed distance values provides a function-based representation of the object. A signed distance value model of a second object is obtained, and one or both sets of signed distance values are manipulated to perform a CAD operation.