| Based on the theory of radiative transfer and Monte Carlo simulation, this paper studies the BRF of two typical vegetation scenarios. The vegetation scenarios include homogeneous and discrete vegetation scene. Main tasks are as follows:1. The structural parameters of the vegetation reflectance model are introduced, and the leaf area index measurement method and the statistical law of the leaf angle distribution function of the characteristic parameters of the vegetation is discussed. The leaf area index of winter wheat is measured by using the method of photography. 2. For homogeneous vegetation scene, this paper introduces the foreign SAILH model, which is based on the radiative transfer theory. The influences on uniform vegetation bidirectional reflectance factor simulation of different parameters such as leaf area index, leaf angle distribution and size of the leaf are discussed of two bands, combined with traditional Monte Carlo statistical estimation method, considering the leaf inclination angle distribution, sampling leaf inclination angle direction, the conversion between leaf local coordinate system and canopy coordinate system is established. The interation process between the light and vegetation is represented, and the influence of different parameters on the simulation results is analyzed. In the red and near infrared bands, for the same wheat scene, the bidirectional reflectance factor is compared between the MC and SAILH model with the long-term changes. 3. According to the research of discrete vegetation scene, based on the research of bidirectional reflectance factor of homogeneous vegetation, considering the geometrical structure of vegetation, the common methods of generating realistic scenes are summarized, and the FLIGHT and MGEOSAIL models are discussed. The two models are used to simulate the optical charactristics of large and discontinuous sparse vegetation scenes. The simulation results of FLIGHT model are compared with the results of MC simulation, and the reliability of this method is verified. |
