Time-varying Hyperspectral Characteristics of Typical Terrains

In order to make the visible and infrared characteristic of a camouflaged target closer to real background environment such that an effective fusion of the target and the background is achieved, it is necessary to study the hyperspectral signatures and analyze the performance for both target and background under various sun illumination at different time intervals by using imaging spectroscopy techniques. In this work, through outdoor field hyperspectral observations of six kinds of typical terrains such as grasslands, bare soils, concrete road and trees, the spectral image sequences are acquired under different solar conditions from 7:00 A.M to 15:00 P.M daily. It is found from the experiment results that the positions of the characteristic peak and valley kept stably fixed, while the reflectivity varies with noticeably different trends. The matching among the spectral data for different terrains are implemented and analyzed. It is seen that in visible band, the spectral matching values of wet soil, dry soil and bare soil are similar, while the spectral angle of wet soil is quite different from that of bare soil. On the other side, the matching values of trees and grassland are similar in both visible and near-infrared bands. The results obtained are of great importance as a reference for designs of optical camouflage and stealth materials as well as for camouflage performance evaluation.