MODIS image-based apparent reflectance model construction method and system and calibration method

Abstract

The invention relates to an MODIS image-based apparent reflectance model construction method and system and a calibration method. According to the construction method, corresponding image apparent reflectance and related angle information through selecting an effective calibration field image; a nuclear driving model is utilized to obtain an apparent reflectance correction coefficient, so as to establish an apparent reflectance model; and the apparent reflectance model is used for obtaining apparent reflectance, so as to cross calibration between different sensor satellite image pairs. The construction method is suitable for in-orbit calibration of multi-spectrum satellites, particularly the cross calibration between large-angle images; and the method has the advantages of being high in calibration precision and being used for re-calibration of history data. Satellite-earth synchronous experiments do not need to be carried out, and the assumption that lambert performance must exist atthe field is cancelled, so that the cross calibration of small-angle images can be realized, and the cross calibration of large-angle images can be realized, thereby greatly improving the calibrationfrequency and precision.

Description

technical field [0001] The invention relates to a MODIS image-based apparent reflectance model construction method, system and calibration method, belonging to the technical field of calibration and calibration. Background technique [0002] High-precision, high-frequency on-orbit radiometric calibration is the premise and basis for the inversion of quantitative remote sensing products. On-orbit radiation calibration is to use a specific target on the ground or on the satellite as a reference radiation source during satellite operation to establish the conversion relationship between radiance and image gray value to obtain the calibration coefficient of the sensor. According to different reference radiation sources, on-orbit radiation calibration methods are divided into on-board calibration method, solar calibration method, lunar calibration method, field calibration method, scene calibration method, cross calibration method, etc. . Among them, the calibration method of t...

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Problems solved by technology

However, the disadvantage is that the calibration accuracy is limited by the model of the calibration scene. This method assumes that the scenes in different time phases in different regions have the same model. , the differences in surface changes, this assumption has a large uncertainty, resulting in low accuracy of the scene calibration method

[0005] To sum up, in the existing cross-calibration methods, the difference in directional reflectivity between satellite image pairs under large observation angles is less considered, or the influence of the directionality of the apparent reflectivity at the top of the atmosphere is replaced by the ground-measured reflectivity, resulting in Existing cross-calibration methods are not suitable for cross-calibration of large observation angle satellite image pairs

In the actual calibration process, the observation angles of most cross-calibration image pairs will have large differences.

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