Automatic building of radiographic flexible models using a set of examples

Because of the intrinsic superimposition of structures in radiographies, their interpretation is a complex task. However, in such a situation, prior information on some of the observed objects is often available. For example, a set of reference radiographies of some structures may be available. Unfortunately, the objects' geometry is not perfectly reproducible. Thus, differences can occur between the object considered in reference radiographies and the one present in the radiographies. The authors propose a way to take into account the the deformations between the reference objects and the observed objects. A flexible model of the reference objects' radiographies is built up. This model is "learned" from radiographies of a set of reference objects. In the second section, various ways to build up a flexible model are compared. In the following section an automatic way to design a model adapted to deal with tolerances in radiographies of a class of 3D deformable objects is proposed. Finally, all applications of the method to quantitative printed circuit board solder inspection are presented.<>