Conventional fixed imaging sensors are mostly used to analyze the changes of spectrum resulting from changes in the biochemical parameters of the ground objects. However, the computer simulation model used to study the bidirectional reflectance characteristics can not complete the simulation of multiple types of ground objects because of the large amount of view factors that need to be calculated when constructing a scene. Therefore, there is less connection between them. To deal with these problems, based on the Radiosity Applicable to Porous Individual objects (RAPID), we simulate the reflectance of the Yuhuayuan area in Changchun City and analyze the sensitivity of the reflectance to the environment factors. The results show that the field of view of the sensor has a strong influence on hot spot. The solar zenith angle and sky light ratio have a strong influence on all directions of the visible and near-infrared bands. Simulating the influence of environmental factors on the imaging spectrum is a good way to provide the basis for inversion of the ground objects of the biochemical parameters of fixed imaging sensor.