Relation between thermal infrared and visible/near-infrared images of natural scenes: an overview

Abstract

A Physical for the relation between reflective and thermal IR images of natural ground scenes is presented and discussed. The model enables the formulation of the joint distribution density function for the emitted radiance and its diurnal behavior. An approximated analytic expression for the multiband correlation coefficient is derived from the explicit form of the joint distribution function is calculated and presented. The effect of local scene topography and heat transfer mechanisms of vegetation on the obtained correlation coefficient is presented and analyzed. The main effect of the local scene topography is by introduction shaded areas which emit low radiance both in the thermal l and the reflective images. Vegetative objects regulate their temperature through evapotranspiration during daytime and hence usually becomes the coldest objects in the scene as their appearance in a visible image. Local scene topography effect can be estimated through a reasonable quantitative assessment of surface roughness characteristics and the relative geometry of the sun and the observation point. The resistance of vegetation to the external heat load is modeled via daytime and nighttime effective heat conduction. The effective heat conduction represents the unique heat transfer results which back the proposed model are presented. The model can be readily extended in order to describe the mutual relation between multispectral reflective images and thermal images. Furthermore, it enables us to interpret the effect of the addition of the thermal data on principal component analysis. The practical application of the model and its derived conclusions in the fields of remote sensing and data fusion are discussed.