Rapid calculation of local topographic correction based on GPU parallel prism method

• Main Authors: HUANG Yan, WANG Qingbin, FENG Jinkai, XING Zhibin, FAN Diao, TAN Xuli, LÜ Minghao
• Format: Article
• Language: zho
• Published: Surveying and Mapping Press 2020-11-01
• Series: Acta Geodaetica et Cartographica Sinica
• Subjects: earth's gravity field; local topographic correction; gpu; cuda; rigorous prism integration; acceleration ratio
• Online Access: http://xb.sinomaps.com/article/2020/1001-1595/2020-11-1430.htm
• ISSN: 1001-1595; 1001-1595

In gravity reduction, local topographic correction is of great significance in the fields of gravity exploration, crustal structure analysis and geoid calculation. However, the calculation efficiency of strict prism formula is low, while the calculation accuracy of fast formula will be reduced. In this study, it is proposed that a method of topographic grid re-encoding and an eight-component strict prism integral disassembly using a CUDA parallel programming platform which realizes a fast parallel algorithm of topographic correction based on CPU+GPU heterogeneous parallel technology. The problem of task allocation and thread overload in each thread of GPU is effectively solved. And the high score of local topographic correction is solved. The results of this study provide a rigorous, fast, and accurate solution for high-resolution and high-precision topographic correction. Experimental verification shows that it takes only 1.5 s to calculate the local topographic correction in the range of 4°×6°, with the integral radius of 40' and the resolution of 1' using Tesla V100, and only 14.6 min to calculate the local topographic correction with 10″ resolution and 40 minute integral radius. It takes 45.7 h to calculate the 3″ resolution, while the traditional serial algorithm is difficult to complete the calculation. Under the condition of guaranteeing the accuracy above the micro-Gal level, the acceleration ratio of calculation can reach more than 850 times, which effectively shortens the calculation time and improves the calculation efficiency. Based on the parallel algorithm mentioned above, the topographic correction in China is calculated. The result shows that the topographic correction in China is generally lower than 80 mGal (1 Gal=10^-2 m/s²), with an average of 1.83 mGal and a maximum of 196 mGal.