On-Orbit Relative Radiometric Calibration of the Night-Time Sensor of the LuoJia1-01 Satellite

Autor: Xin Shen, Li Litao, Deren Li, Guo Zhang, Yonghua Jiang
Jazyk: angličtina
Rok vydání: 2018
Předmět:
Zdroj: Sensors
Volume 18
Issue 12
Sensors, Vol 18, Iss 12, p 4225 (2018)
Sensors (Basel, Switzerland)
ISSN: 1424-8220
DOI: 10.3390/s18124225
Popis: The LuoJia1-01 satellite can acquire high-resolution, high-sensitivity nighttime light data for night remote sensing applications. LuoJia1-01 is equipped with a 4-megapixel CMOS sensor composed of 2048 ×
2048 unique detectors that record weak nighttime light on Earth. Owing to minute variations in manufacturing and temporal degradation, each detector&rsquo
s behavior varies when exposed to uniform radiance, resulting in noticeable detector-level errors in the acquired imagery. Radiometric calibration helps to eliminate these detector-level errors. For the nighttime sensor of LuoJia1-01, it is difficult to directly use the nighttime light data to calibrate the detector-level errors, because at night there is no large-area uniform light source. This paper reports an on-orbit radiometric calibration method that uses daytime data to estimate the relative calibration coefficients for each detector in the LuoJia1-01 nighttime sensor, and uses the calibrated data to correct nighttime data. The image sensor has a high dynamic range (HDR) mode, which is optimized for day/night imaging applications. An HDR image can be constructed using low- and high-gain HDR images captured in HDR mode. Hence, a day-to-night radiometric reference transfer model, which uses daytime uniform calibration to calibrate the detector non-uniformity of the nighttime sensor, is herein built for LuoJia1-01. Owing to the lack of calibration equipment on-board LuoJia1-01, the dark current of the nighttime sensor is calibrated by collecting no-light desert images at new moon. The results show that in HDR mode (1) the root mean square of mean for each detector in low-gain (high-gain) images is better than 0.04 (0.07) in digital number (DN) after dark current correction
(2) the DN relationship between low- and high-gain images conforms to the quadratic polynomial mode
(3) streaking metrics are better than 0.2% after relative calibration
and (4) the nighttime sensor has the same relative correction parameters at different exposure times for the same gain parameters.
Databáze: OpenAIRE
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