基于BRDF测量的Schlick模型改进方法研究

In simulating an infrared scene, the Schlick model uses a commonly-used bidirectional reflection distributional function(BRDF) model. Through simulation and BRDF measurement, this paper points out that the Schlick model is in better agreement with the actual output when the emerging zenith angle is smaller than the incident zenith angle. But when the emerging zenith angle is a certain angle larger than the incident zenith angle, the output of the function value may increase with the increasing emerging zenith angle and may not be in agreement with the actual output. In this paper, a new improved Schlick model is proposed, and a cosine compensation function is designed based on Lambert reflection principle. When the zenith angle is larger than the incident zenith angle, which guarantees the monotonous decreasing of the output of the function through the compensation function when the emerging zenith angle is larger than the incident zenith angle. The results on comparison with experimental data show that the improved Schlick model is basically in agreement with experimental results. The results on comparison with the heightened illumination effect of the fighters model show that the heightened illumination effect produced with the improved Schlick model is superior to that produced with the original Schlick model.