Two Methods of Acquiring BRDF of Object in the Field Simulated with Radiosity-graphics Combined Model and Error Analysis
两种BRDF室外测量方法的RGM模拟对比与误差分析

The bidirectional reflective characteristic of objects plays an mi portant role not only in models of remote sensing but also in inversion. Consequently, it is the basis ofquantitative analysis in remote sensingwith the appropriate method of acquiring the bidirectional reflective characteristic of objects in natural environment. For a long period, BRF (BidirectionalReflectance Factor) acquired in natural environmentand related to radiantenvironment, is regarded as the expression ofbidirectional reflective characteristic ofobjects. There are differenceswhichmustbe considered betweenBRF and real value except in a strict clear day. In order to elmi inate the influence of the environment radiance, somemethod acquiring BRDF (Bidirectional Reflectance Distribution Function) data of objects in natural environment have been designed. But the erroroccurred in thesemethod hasnotbeen strictly analyzed. In thispaper thesemethods are compared by using radiosity-graphic combined model based on three dmi ensional structures which is one of computer smi ulation mode.l And their fixed error affected by conditions acquiring BRDF data is analyzed in the smi ulation. We also provide principles to choose the suitablemethod of acquiringBRDF data in natural environment. By these principleswe can take the most suitable method under different conditions in order to reduce the error and get acceptable value from measurement.