GF-4大气校正并行算法研究

Study on Parallel Method of Atmospheric Correction for GF-4 Images

高分四号(GF-4)是我国第一颗高分辨率对地静止卫星,地表反射率产品对于评估生态环境与减灾防灾具有重要价值。GF-4大气校正算法对地表反射率进行估计,迭代计算观测与计算表观反射率残差最小值得到气溶胶光学厚度,并构建6SV查找表对地表反射率结果进行计算。在精度验证基础上,考虑产品生产的高效率需求,对计算复杂度高的步骤基于图形处理器(GPU)进行内核设计,实现线程、寄存器等性能优化。研究结果表明,基于GPU加速的大气校正算法在性能与能耗上具有较大优势,一景GF-4 PMS的10240×10240像元数的影像数据,相比顺序执行取得57.3的总体加速比,而总体能耗仅为顺序执行的15.5%。

GF-4 is the first high spatial-resolution geostationary satellite of China.Surface reflectance products are of great value for evaluating ecological environment and reducing disasters.GF-4 atmospheric correction algorithm estimates surface reflectance,iteratively calculates the minimum residual error of observed and calculated apprent reflectance to get aerosol optical depth,and constructs a 6 SV look-up table to obtain the surface reflectance results.Based on the accuracy verification of GF-4 surface reflectance products,considering the high-efficiency requirements of data analysis and product production,the computationally complex steps are designed based on the graphics processing unit(GPU)to optimize the performance of threads and registers.The results show that the GPU-accelerated atmospheric correction algorithm has great advantages in performance and energy consumption.Compared with sequential execution,a scene of GF-4 PMS image data with 10240×10240 pixels has an overall speedup of 57.3,while the overall energy consumption is only 15.5%of sequential execution.