扩展真实结构模型模拟植被冠层半球图像

Extending Realistic Structural Model to Simulate Hemispherical Photography of Vegetation Canopies

半球成像技术是植被冠层结构非接触测量方法中的重要手段之一,但是在提取针叶林等复杂植被结构参数方面精度较低。目前,利用多波段计算和多相机比对来提高精度成为研究热点。由于仪器和环境条件限制,地面试验较为困难,因此开展半球图像模拟试验非常必要。目前的模拟研究仅集中在可见光波段,且多考虑单次散射,因而不适应多波段的模拟需求。基于球形投影和画家算法,对计算机真实结构模型RGM进行了扩展,充分考虑多次散射,实现了可见光、近红外和热红外多波段植被半球图像的快速模拟。模拟实例显示,扩展模型能有效而逼真地模拟不同类型冠层下方的不同波段的半球图像,并在可见光波段模拟出较好的太阳和天空效果。该扩展模型将为植被冠层结构测量和遥感反演研究提供有利支撑。

Hemispherical imaging technology is one of the important methods for non-contact measurement of the vegetation canopy structure.However,the accuracy does not satisfy complex vegetation such as coniferous forest.Nowadays,it is popular to use multiple-bands-based calculations and multiple-camera comparisons to solve that problem.Due to the limitations of instrument and environment condition,the field experiment is difficult to conduct.Therefore,the simulation of hemispherical images is necessary.Literature review shows that there isn＇t any proper model to simulate the hemispherical photography by considering multiple scattering in the full optical range（visual,near infrared and thermal infrared bands）.Based on the spherical projection and the painter algorithms,the realistic structural model RGM was extended to simulate hemispherical photography in the full optical range with accurate multiple scattering calculations.Simulation results show that the extended model is efficient to simulate the hemispherical photography in both visible,near infrared and thermal infrared range for different types of canopies.The sun and sky effects are also be simulated.The model will be beneficial to support the research on the vegetation canopy structure measurements and remote sensing inversion