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