The measurements of directional emissivity of the ground objects using a new design device with CO/sub 2/ laser

摘要

The emissivity usually referred to is the normal emissivity. In fact, however, the directionality of the emissivity has an important effect on the measurements when land surface temperature is deduced. The directional emissivity is one of the three factors that impact on thermal radiation. Directional reflectivity in the thermal infrared waveband were measured by using CO/sub 2/ laser in the Thermal Infrared Remote Sensing Laboratory of Institute of Geography of Chinese Academy of Sciences (1986) and the Laboratory For Image Science And Remote Sensing of France. (1990). In this paper a new design device for measuring directional emissivity has been made. The new device has improvements of designs mentioned before. This instrument is used to measure the directional emissivity of some types of marble. This new method is suitable to samples, which are set horizontally. The paper first explains the principle of this method for this instrument, and discusses some questions during the measuring process. The experiment data of marble samples are processed and analyzed. Afterward the curves of the directional emissivity of these measured objects are given. The multi-angle information from remote sensor usually results from several factors such as measuring angle, field of view (pixel components), and so on. So through analysis the authors manage to identify what is the vital key to modeling of thermal radiation and the inversion of surface temperature.