Research And Implementation Of Log Curve Vectorization Methods And Reduiding Technique

Engineering drawing vectorization is the process of analyzing and recognizing the image of engineering drawing, and finally rebuilding the graphic objects. Well log graph, which is used for the exploitation of oil and natural gas, is a kind of engineering drawing. Digitizing well log graph is favorable for storing, managing, analyzing, sharing and network transmitting well log information. Therefore vectorizing log curve becomes one of the key tasks for each oil field. Nowadays, vectorization of log curve is usually accomplished by the digitizer or foreign vectorizing software, but the vectorizing speed is relatively slow and the vectorizing efficiency is relatively low. How to recognize and pick up log curve from the well log graph automatically and rapidly, therefore, remains to be an emergent unresolved problem.In order to solve the problem, this paper researches on automatic recognition and extraction of log curve that covers the following content:1. We design a global curve vectorization method based on sparse pixel tracing. This method traces the curve by its local slope coefficient and automatically adjusts its tracing direction and step length. The added searching function of this method can not only traverse the intersecting and adhesive part of the curve correctly, but also leap over the curve gaps. This method involves five basic processes, namely start point and initial tracing direction confirmation process, the normal tracing process, correct and recovery process, searching process, and key point picking process.2. We put forward the curve rebuilding strategy based on B-Spline interpolation and express the primary curve with B-spline curve. The B-spline function has many advantages that other spline functions don't have, for example, forming curves of random shape, influencing only very few neighbor curved sections if moving a point. The strategy would first calculate the B-spline curve's control points according to the given points, and then interpolate the B-spline to form the curve.Based on the key techniques mentioned above and the previous study, this paper finally accomplishes a complete well log graph digital system, which can digitize all well log graph information, including graph head, legends, curve instructions, graph grids, curves, log interpretation table and so on, and all the digital information is stored in the database. This system can get digital well log graph information that has been stored in the database and rebuild the well log graph according to the rebuilding method, that is, to rebuild all graphic objects on a new image.