A Radiation Correction Method for Framed FPI Hyperspectral Images

Abstract

The invention discloses a radiation correction method of a frame-type FPI hyperspectral image. Through calibration and correction at a spectral imager system level, a dark current caused by non-illumination in a light-sensitive unit and a lens attenuation effect of edge incident light are eliminated. In a radiation treatment portion, a non-ideal solar illumination condition results in a large radiation difference among images. A global median illumination correction method is used to eliminate a radiation brightness gradient difference caused by illumination changes between air strips. Based on image bottom point standardization BRDF correction, the brightness gradient difference associated with an observed angle and direction in a scene is eliminated. A spectral curve is polished throughusing Savitzky-Golay filtering, and an atmospheric-correction residual absorption peak burr noise is eliminated. A signal-to-noise ratio of the filtered image is obviously improved, especially in an original low signal-to-noise ratio wave band. Besides, a signal-to-noise ratio improvement effect in a near-infrared band is better than that in a visible light band, and an improvement range is about5 units.

Description

technical field [0001] The invention relates to the field of aerial remote sensing image preprocessing, in particular to a radiation correction method for framed FPI hyperspectral images. Background technique [0002] The rapid development of Fabry-Perot interferometer (FPI) technology makes hyperspectral imager one of the new technologies, and it can be extended and applied to the field of aerial remote sensing. In remote sensing imaging, due to the influence of instrument detection components, atmospheric environment and sunlight, there will be certain radiation distortion in remote sensing images, which affects the quality and application of images. Especially when the weather conditions are not good, the data collected under non-uniform illumination conditions, because the solar radiation received by the surface is seriously affected by the clouds, the radiation distortion problem exists in the pixels under different illumination levels, which increases the spectrum of g...

AI Technical Summary

Problems solved by technology

However, in many seasons or climate regions, ideal weather is rare, resulting in low utilization of equipment

Existing radiation processing methods do not provide radiation processing methods after imaging spectroscopy measurements under non-ideal weather conditions

When performing imaging spectrum measurement under non-ideal weather conditions, sunlight will be refracted and reflected by clouds of different thicknesses, the radiation intensity and wavelength reaching the target object will change, and the corresponding reflected light will also change synchronously, causing the sensor The measured radiant energy yields large differences

That is to say, the remote sensing image of the same ground object will be affected by factors such as atmospheric environment, solar illuminance, solar azimuth angle, and solar altitude angle. There are differences in the reflectance spectrum imaged at different time and illuminance levels, which is manifested as uneven brightness on the image.

Radiation correction is required to reduce or eliminate this radiation distortion. Common correction methods require an external radiometer to obtain a correction reference. Although the correction accuracy is high, it has disadvantages such as high cost, difficult operation and low efficiency.

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