The Cavern Digital Catalog System Image Pre-processing Technology

Geological catalogue of construction period is especially important for hydropower and water resources project, transportation engineering and underground structure. It usually serves as a base of joints statistics and analysis, engineering design and construction management, analysis of rock stability for underground structure, etc. The main objects for geological catalogue of construction period for tunnel include the gross physical character of a rock or rock formation, the stratum boundary, the weathering boundary, the attitude and property of joints and faults, the kinds and property of filling, etc.The traditional method of geological catalogue is based on handwork. It is inefficient and also difficult to check up after the event.At present, there are some design institutes and colleges, which are researching the methods of geological catalogue based on camera, and some beneficial experiences have been gained as well.Depended on common digital camera, the paper presents the digital image correction and sewing technique of the catalogue system for tunnel, and concentrates on the four essential problems concerned with DIP. Firstly, based on function fitting, the paper presents a method that can modify barrel distortion of DC. The error is analyzed as well, and the best one selected. Secondly, aimed at perspective distortion, the writer researched the perspective mapping between object and its image, also built corresponding formulae. Again, according to gray distortion resulted from asymmetric illumination, the paper presents a method of radiation correction based on high pass filtering, which is proved to be robust. Finally, this paper introduced a arithmetic for sewing pictures. The sewing method is a arithmetic based on grad and edge detection, which can adjust image matching error. It can deal with matching error resulted from asymmetric brightness and rotation error.Compared with the traditional method, the new method of geological catalogue based on digital camera can greatly improve the precision of geological catalogue. The method is efficient, convenient to file and can check up the data afterwards.