Abstract: The angular effects of emitted radiation from non isothermal land surface are the basis for component temperatures retrieval from multi angle thermal infrared remote sensing data. This paper reviews two different directions in the studies of this field. One is to define new concepts of emissivity, for example, the "e emissivity", "r emissivity", the band averaged emissivity, and "canopy emissivity" et al. Some of the them are component temperatures dependent. Another is to build thermal radiant model to illustrate the emitted radiation from non isothermal mixed pixel. This paper then shows the recent progress of this field in China. It also points out in final section that several trends should be strengthened, such as the basic theories and concept, the remote sensing field measurement, the simplification and test of radiant model, and algorithms of component temperatures retrieval from multi angle data of thermal infrared remote sensing.

Key words: non isothermal mixed pixel, radiant directionality