[Study on multi-angular polarized spectrum characteristics of leaf based on some indoor experimental data].

In the present study, we acquired multi-angular polarized spectrum of three kinds of leaves with different surface structures, and calculated the multi-angular spectral degree of polarization DOP based on Stokes parameters to explore its variation tendency with wavelength and the relationship between the leaf polarized reflectance and its physiological parameters and the relative observational geometric condition. The results show that although the spectral degree of polarization of the 3 kinds of leaves has obvious differences in value because of the leaf surface structures, the general trend of the DOP curve keeps consistent, and this trend could be explained by analyzing the properties of both specular and diffuse components of the leaf reflectance. The peak value of the DOP appears in the specular direction of the principal plane, and grows with the increase in the incident zenith angle.

[Optical methods for in situ measuring leaf area index of forest canopy: a review].

Leaf area index (LAI) is an important parameter of canopy structure, because it relates to many biophysical and physiological processes of canopy, including photosynthesis, respiration, transpiration, carbon cycling, precipitation interception, and energy exchange, etc. This paper introduced the theoretical bases and mathematical models of optical methods for forest canopy LAI determination, introduced the principles, merits, and drawbacks of currently used optical methods, and summed up the main sources of the errors in LAI optical measurement, including clumping effect, non-photosynthesis components, measurement conditions, and terrain effect. The developing status of quantitatively evaluating clumping effect, non-photosynthesis components, and terrain effect was analyzed, and the promising development directions of optical methods for measuring forest canopy LAI were discussed.

[Retrieval of spectral characteristics of hyperspectral sensor and retrieval of reflectance spectra].

On-orbit spectral calibration of hyperspectral imaging data is a key step for quantitatively analyzing them. Like the atmospheric correction, accurate spectral calibration is very necessary for improved studies of land or ocean surface properties. Based on the previous literatures, a new method which coupled an optimization algorithm was developed to simultaneously retrieve the central wavelength and the full width at half maximum (FWHM) of the hyperspectral sensor without needing the in situ reflectance spectra.

[Winter wheat growth spatial variation study based on temporal airborne high-spectrum images].

Precision agriculture technology is defined as an information-and technology-based agriculture management system to identify, analyze and manage crop spatial and temporal variation within fields for optimum profitability, sustainability and protection of the environment. In the present study, push-broom hyperspectral image sensor (PHI) image was used to investigate the spatial variance of winter wheat growth. The variable-rate fertilization contrast experiment was carried out on the National Experimental Station for Precision Agriculture of China during 2001-2002.