Cross-radiation calibration method and system for large observation angle sensors

Abstract

The invention provides a cross radiation calibration method and system for a large observation angle sensor. The method comprises steps that a to-be-calibrated image and a reference image are registered, random sampling of each set of corresponding wave bands of the to-be-calibrated image and the reference image is respectively carried out to acquire corresponding calibration points; for each wave band, cross calibration for each pair of calibration points is carried out respectively, a BRDF adjusting coefficient is established as a ratio of a surface bidirectional reflection distribution function of the to-be-calibrated image and a surface bidirectional reflection distribution function of the reference image, and processing is carried out in an iteration mode; for each wave band, points with average mean values greater than a preset threshold are deleted from the cross calibration result, averaging is carried out, and a final radiation calibration coefficient is acquired. The method is advantaged in that BRDF values of the to-be-calibrated image and the reference image can be respectively calculated without a complex model, calculation is simple and stable, strong operationality is realized, and an error caused by introducing auxiliary data for BRDF calculation and influence of abnormal calibration points on the result can be further avoided.

Description

technical field [0001] The invention relates to a cross-radiation calibration method and system based on data assimilation for large observation angle sensors, and belongs to the technical field of remote sensing image processing. Background technique [0002] With the deepening of remote sensing applications, the mainstream remote sensing technology at home and abroad has developed from qualitative analysis to quantitative research, and radiometric calibration is the basis and premise of quantitative remote sensing. Radiation calibration is to convert the dimensionless digital quantization value (DN value) recorded by the sensor into the radiance or reflectance of the top layer of the atmosphere with actual physical meaning. Its main functions are as follows: (1) through dynamic monitoring, correct the performance decay of the sensor, correct the influence of the atmosphere, light conditions and environmental changes on the measurement results, and ensure that the measureme...

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Problems solved by technology

Therefore, for satellites with large observation angles, the traditional cross-calibration method cannot obtain accurate radiation calibration coefficients due to the lack of consideration of atmospheric radiation transfer or the differences in the distribution of ditropic reflections on the surface

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