In traditional practice, a seismic analyst will produce an image that is then sent to a structural geologist for interpretation and the construction of a geologic cross-section. A problem with that practice is that the features that are important to the geologist-relationships between geologic beds, the dip on structures, the thickness of beds, and so on-may have been given little consideration by the analyst. Similarly, the analyst may have little information as to the geologic constraints of the region being imaged-information that would aid in producing a more accurate image. The ISIS project was originally conceived in an attempt to blend the roles of analyst and geologist. In the role of geologist the user can make use of the interactive imaging facilities to gain useful information about the character and robustness of the imaged structure. A structural geologist provided with an interactive processing system can develop a much more thorough, dynamic understanding of the image than would ever be possible through the examination of a static section produced through some unknown processing sequence. In the role of analyst the user may apply geologic constraints and intuition to improve the imaging process. While we will continue to refer to the seismic analyst throughout this paper, we believe that through the use of interactive imaging the distinction between geologist and analyst will disappear.
As mentioned above, the principal task of the structural geologist is to interpret a seismic section and produce a geologic cross-section of a prospect. The act of making this interpretation also implicitly creates a seismic model. It should therefore be possible to use this as the input model in the imaging process. An image produced in this way should be very similar to the image from which the interpretation was originally made; if not, there is reason to suspect the accuracy of the model. A future addition to ISIS will allow the geologist to make interpretations as the imaging system honors the interpretation in recomputing the image. This process will further break down the barrier between imaging and interpretation, and between geologist and analyst.