Abstract
GaoFen-4 (GF-4) infrared spectrum (IRS) camera has a special spectral band located in the mid-wave infrared spectrum with the wavelength ranging from 3.50 to 4.10 μm. It is very important for forest fire-detection and other quantitative remote sensing applications at a high spatial resolution of 400 m. Due to the similarity of the spectral characteristics, the thermal emissive band 20 (3.660-3.840 μm) and 22 (3.929-3.989 μm) of medium resolution imaging spectrometer (MODIS) are taken as the reference bands for the radiometric cross-calibration of the GF-4/IRS camera. The time difference between selected GF-4/IRS and MODIS images at the Qinghai Lake and Se lincuo Lake test sites is less than one hour. After spatial matching, single-band and dual-band spectral matching methods are proposed in this article. Then, the DN value of GF-4 image is linearly fitted to the radiance of the corresponding MODIS image to obtain the radiometric calibration coefficients of GF-4/IRS camera. The validation results show that the cross-calibration coefficients calculated by integrating the measurement of two MODIS bands with the mean value spectral matching approach has the highest radiometric calibration consistency with the official calibration coefficients.
Highlights
GF-4 is the only geostationary remote sensing satellite in China's high-resolution Earth Observation System (CHEOS), which was successfully launched on December 29, 2015 [1]
In this paper, based on the single-band method, we proposed the dual-band method to take the spectral difference between two sensors into account
According to the linear fitting method, all of the matching points extracted from three image pairs listed in Table I are put together to obtain the cross-calibration coefficients with five schemes including (a) single-band method using MODIS band 20, (b) single-band method using MODIS band 22, (c) dual-band method with the mean value approach, (d) dual-band method with the intersection value approach, and (e) dual-band method with the CW distance approach
Summary
GF-4 is the only geostationary remote sensing satellite in China's high-resolution Earth Observation System (CHEOS), which was successfully launched on December 29, 2015 [1]. Cross-calibration is an alternative way to acquire the radiometric coefficient of the remote sensor It uses a well-calibrated sensor as a reference and compares the radiometric response of two sensors over the same target within a small imaging time difference. Yang et al used MODIS to calibrate the thermal infrared channel of HJ-1B, compared and analyzed observation angles and imaging time difference to obtain higher calibration accuracy [12]. The experimental results showed that the accuracy of the calibration coefficient obtained by the twopoint method is higher than that of the single point method [13] This satellite no longer provides observation service. MODIS, a multi-band remote sensor with high radiometric calibration accuracy, is selected as the reference sensor to cross-calibrate the GF-4/IRS sensor. Step 3: Search for simultaneous images over test site for both sensors
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