Modeling and reasoning techniques in geologic interpretation

A thorough investigation is reported on the qualitative modeling of geologi c systems, focusing on the reconstruction of three-dimensional (3-D) profil es from image data by means of spatial and temporal reasoning techniques. A conceptual model of the relevant knowledge is proposed for both the domai n elements and the inference processes. At the former level, we describe th e objects in terms of geometric primitives and relations among them; at the inference level, reconstruction is identified as a synthesis task, in whic h a 3-D model of underground bodies results from assembling simpler compone nts. The process is incremental and nonmonotonic, according to a basic Asse mble-Validate-and-Debug cycle, underlying both low-level and high-level ste ps. A formal (logical) model of the latter is proposed and worked out in de tail. Concepts from topology and graph theory provide effective tools to de fine representations and algorithms, and allow to address the intertwining of spatial and temporal knowledge. Some relevant reasoning steps are also regarded as constraint satisfaction problems. We analyze the constraints, show that the related tasks can be so lved with algorithms of polynomial complexity, and provide the appropriate procedures. The practical feasibility of the model has been tested, and res ults of the applications to realistic input data are discussed. We also dis cuss solutions for embedding the modules into a man-machine interface for t he intelligent support to the interpretation of data.