2D efficient ray tracing with a modified shortest path method
Meigen Zhang 1 2 4 Liyun Fu 2 Xinfu Li 3 Xiaofan Li 21 Key Laboratory of Engineering Geomechanics, Chinese Academy of Sciences, 19 Beitucheng Xilu, Beijing 100029, China.
2 Key Laboratory of the Earth’s Deep Interior, Institute of Geology and Geophysics, Chinese Academy of Sciences, 19 Beitucheng Xilu, Beijing 100029, China.
3 China University of Geosciences, Beijing 100081, China.
4 Corresponding author. Email: mgzhang@mail.iggcas.ac.cn
Exploration Geophysics 40(4) 301-307 https://doi.org/10.1071/EG09016
Submitted: 6 March 2009 Accepted: 13 November 2009 Published: 7 December 2009
Abstract
The computation effort of ray tracing with the shortest path method (SPM) is strongly dependent on the number of the discretized nodes in a model and the number of ray directions emanating from a secondary source node. In the traditional SPM, a secondary source emanates rays to all the surrounding nodes. Obviously, most of them are not minimal traveltime raypaths. As a result, the efficiency of SPM can be greatly improved if some measures are taken to avoid those unnecessary computations. In the current study, we apply the traveltime information of neighbouring nodes and the incident rays to determine the effective target propagation directions of secondary source nodes in 2D case. Generally, the effective propagation directions are narrow bands with few surrounding nodes. Thus, most unnecessary ray directions of secondary source nodes are avoided. 2D model tests show that the computational speed of the improved method is about several to tens of times of that of the traditional SPM with the increase of network nodes and cells.
Key words: shortest path method, efficient ray tracing, effective propagation direction.
Acknowledgements
This work is sponsored by Key Laboratory of Engineering Geomechanics of Chinese Academy of Sciences, CNPC Innovation Fund and National Natural Science Foundation of China (grants 40437018 and 40874024). We thank the editors and two referees for their useful comments, which were of great help in improving the quality of this manuscript.
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