Modeling and reasoning techniques in geologic interpretation

A thorough investigation is reported on the qualitative modeling of geologic systems, focusing on the reconstruction of three-dimensional (3-D) profiles from image data by means of spatial and temporal reasoning techniques. A conceptual model of the relevant knowledge is proposed for both the domain elements and the inference processes. At the former level the authors describe the objects in terms of geometric primitives and relations among them; at the inference level, reconstruction is identified as a synthesis task, in which a 3-D model of underground bodies results from assembling simpler components. The process is incremental and nomnonotonic, according to a basic assemble-validate-and-debug cycle, underlying both low-level and high-level steps. A formal (logical) model of the latter is proposed and worked out in detail. Concepts from topology and graph theory provide effective tools to define representations and algorithms, and allow one to address the intertwining of spatial and temporal knowledge. Some relevant reasoning steps are also regarded as constraint satisfaction problems. The authors analyze the constraints, show that the related tasks can be solved with algorithms of polynomial complexity, and provide the appropriate procedures. The practical feasibility of the model has been tested, and results of the applications to realistic input data are discussed. The authors also discuss solutions for embedding the modules into a man-machine interface for the intelligent support to the interpretation of data