GPU-based Calculation for Scattering Characteristics of Complex Targets from Background Radiance in Infrared Spectrum

Scattering characteristic of complex targets from sky and ground background radiance plays an important role in engineering fields. Firstly, a 5-parameter BRDF (Bidirectional Reflectance Distributional Function) model is introduced. Then MODTRAN is used to calculate the background radiance in infrared spectrum of 3-5 um and 8-12um bands. Considering the background radiance comes from all directions of space in large numbers of different bands, there will be multiple loops in the computation thus it's quite time-consuming. Thanks to the NVIDIA CUDA (Compute Unified Device Architecture), programing GPU does not require as much knowledge about graphics card and complex programing interfaces as before. On the basis of CUDA, a parallel implementation is presented and to get a higher speedup the code is optimized to reduce the access latency as much as possible by using the shared and constant memory on GPU. The implementation is test on an NVIDIA GTX GeForce 480 and 2.79 GHz Intel i7 CPU. Compared to the CPU implementation, we achieve a peak speedup of 308 and results showing the efficiency of the parallelism and optimization.