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![]() | Lloyd and Viterbi for QC and auto-picking | ![]() |
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To speed up the velocity analysis loop it is important to allow the computer to do as much as work as possible, particularly in the human intensive picking portion of the loop. As essential is an easy way to evaluate and modify (QC) these automatic picks.
Dynamic programming is an effective tool for finding a solution for certain types of relatively small, non-linear problems such as semblance picking. In biology, dynamic programming is used for pairwise alignment of amino acid sequences (Needleman and Wunsch, 1970). In electrical engineering, it is used for error correction in wireless communication and speech recognition (Hosom et al., 1999) among many other things. We can also find examples of its use in geophysics. Kruse (1988) used dynamic programming for signal correlation and trace interpolation. Kruse (1988) calculates an error function based on the difference in instantaneous frequency between all points along two signals. Dynamic programming is then used to find the error path with the least energy. Liner and Clapp (2004) used dynamic programming for alignment. Zhang (1991) used it for a starting solution when doing event picking.
Quantization is an important field in both electrical engineering and computer graphics. In speech compression, it is important to accurately describe a signal in as few bytes as possible. In image processing, it is often important to reduce the number of colors in image with as little loss in image quality as possible. One family of method often employed in quantization is based on Lloyd's method (Lloyd, 1982), an iterative technique that allows for variable rate quantization. For QCing automatic picks, the ability to reduce densely picked functions to a smaller set of representative points simplifies substantially the QCing process.
In this paper I use a dynamic programming technique to automatically pick semblance gathers and reflectors. In addition, I show that quantization can be used to represent a function by a subset of representative points.
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![]() | Lloyd and Viterbi for QC and auto-picking | ![]() |
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