scholarly journals Research on a Partial Aperture Factor Measurement Method for the Agri Onboard Calibration Assembly

2021 ◽  
Author(s):  
Xiaolong Si ◽  
Xiuju Li ◽  
Hongyao Chen ◽  
Shiwei Bao ◽  
Heyu Xu ◽  
...  
Keyword(s):  
Calibration Method ◽  
Development Trend ◽  
Radiometric Calibration ◽  
Solar Simulator ◽  
High Precision Measurement ◽  
Remote Sensors ◽  
Determination Process ◽  
Calibration Measurement ◽  
Factor Measurement ◽  
Bidirectional Reflection Distribution Function

A partial aperture onboard calibration method can solve the onboard calibration problems of some large aperture remote sensors, which is of great significance for the development trend of increasingly large apertures in optical remote sensors. In this paper, the solar diffuser reflectance degradation monitor (SDRDM) in the onboard calibration assembly (CA) of the FengYun-4 (FY-4) advanced geostationary radiance imager (AGRI) is used as the reference radiometer for measuring the partial aperture factor (PAF) for the AGRI onboard calibration. First, the linear response count variation relationship between the two is established under the same radiance source input. Then, according to the known bidirectional reflection distribution function (BRDF) of the solar diffuser (SD) in the CA, the relative reflectance ratio coefficient between the AGRI observation direction and the SDRDM observation direction is calculated. On this basis, the response count value of the AGRI and the SDRDM is used to realize the high-precision measurement of the PAF of the AGRI B1 ~ B3 bands by simulating the AGRI onboard calibration measurement under the illumination of a solar simulator in the laboratory. According to the determination process of the relevant parameters of the PAF, the measurement uncertainty of the PAF is analyzed; this uncertainty is better than 2.04% and provides an important reference for the evaluation of the onboard absolute radiometric calibration uncertainty after launch.

scholarly journals Vicarious Radiometric Calibration of Ocean Color Bands for FY-3D/MERSI-II at Lake Qinghai, China

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 139
Author(s):  
Shengli Chen ◽  
Xiaobing Zheng ◽  
Xin Li ◽  
Wei Wei ◽  
Shenda Du ◽  
...  
Keyword(s):  
Infrared Imaging ◽  
Large Deviation ◽  
Ocean Color ◽  
Calibration Method ◽  
Surface Measurement ◽  
Radiometric Calibration ◽  
Lake Qinghai ◽  
Vicarious Calibration ◽  
Calibration Methods ◽  
Spectral Imager

To calibrate the low signal response of the ocean color (OC) bands and test the stability of the Fengyun-3D (FY-3D)/Medium Resolution Spectral Imager II (MERSI-II), an absolute radiometric calibration field test of FY-3D/MERSI-II at the Lake Qinghai Radiometric Calibration Site (RCS) was carried out in August 2018. The lake surface and atmospheric parameters were mainly measured by advanced observation instruments, and the MODerate spectral resolution atmospheric TRANsmittance algorithm and computer model (MODTRAN4.0) was used to simulate the multiple scattering radiance value at the altitude of the sensor. The results showed that the relative deviations between bands 9 and 12 are within 5.0%, while the relative deviations of bands 8, and 13 are 17.1%, and 12.0%, respectively. The precision of the calibration method was verified by calibrating the Aqua/Moderate-resolution Imaging Spectroradiometer (MODIS) and National Polar-orbiting Partnership (NPP)/Visible Infrared Imaging Radiometer (VIIRS), and the deviation of the calibration results was evaluated with the results of the Dunhuang RCS calibration and lunar calibration. The results showed that the relative deviations of NPP/VIIRS were within 7.0%, and the relative deviations of Aqua/MODIS were within 4.1% from 400 nm to 600 nm. The comparisons of three on-orbit calibration methods indicated that band 8 exhibited a large attenuation after launch and the calibration results had good consistency at the other bands except for band 13. The uncertainty value of the whole calibration system was approximately 6.3%, and the uncertainty brought by the field surface measurement reached 5.4%, which might be the main reason for the relatively large deviation of band 13. This study verifies the feasibility of the vicarious calibration method at the Lake Qinghai RCS and provides the basis and reference for the subsequent on-orbit calibration of FY-3D/MERSI-II.

scholarly journals Attitude Determination with Magnetometers and Accelerometers to Use in Satellite Simulator

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Helio Koiti Kuga ◽  
Valdemir Carrara
Keyword(s):  
Real Time ◽  
Attitude Control ◽  
Attitude Determination ◽  
Positional Information ◽  
Calibration Method ◽  
Artificial Satellites ◽  
Time Operation ◽  
Determination Process ◽  
Real Time Operation ◽  
Mems Technology

Attitude control of artificial satellites is dependent on information provided by its attitude determination process. This paper presents the implementation and tests of a fully self-contained algorithm for the attitude determination using magnetometers and accelerometers, for application on a satellite simulator based on frictionless air bearing tables. However, it is known that magnetometers and accelerometers need to be calibrated so as to allow that measurements are used to their ultimate accuracy. A calibration method is implemented which proves to be essential for improving attitude determination accuracy. For the stepwise real-time attitude determination, it was used the well-known QUEST algorithm which yields quick response with reduced computer resources. The algorithms are tested and qualified with actual data collected on the streets under controlled situations. For such street runaways, the experiment employs a solid-state magnetoresistive magnetometer and an IMU navigation block consisting of triads of accelerometers and gyros, with MEMS technology. A GPS receiver is used to record positional information. The collected measurements are processed through the developed algorithms, and comparisons are made for attitude determination using calibrated and noncalibrated data. The results show that the attitude accuracy reaches the requirements for real-time operation for satellite simulator platforms.

Radiometric Calibration Method of 2-14 μm Infrared Spectroradiometer

2019 ◽  
Vol 39 (2) ◽  
pp. 0212003
Author(s):  
刘加庆 Liu Jiaqing ◽  
韩顺利 Han Shunli ◽  
孟鑫 Meng Xin ◽  
胡德信 Hu Dexin
Keyword(s):  
Calibration Method ◽  
Radiometric Calibration

Automated Radiation Calibration Method Based on Dunhuang Radiometric Calibration Site

2017 ◽  
Vol 37 (8) ◽  
pp. 0801003 ◽  
Author(s):  
吕佳彦 Lü Jiayan ◽  
何明元 He Mingyuan ◽  
陈 林 Chen Lin ◽  
胡秀清 Hu Xiuqing ◽  
李 新 Li Xin
Keyword(s):  
Calibration Method ◽  
Radiometric Calibration

scholarly journals On-Orbit Polarization Calibration for Multichannel Polarimetric Camera

2019 ◽  
Vol 9 (7) ◽  
pp. 1424 ◽  
Author(s):  
Mingxin Liu ◽  
Xin Zhang ◽  
Tao Liu ◽  
Guangwei Shi ◽  
Lingjie Wang ◽  
...  
Keyword(s):  
Linear Polarization ◽  
Calibration Method ◽  
Experimental Results ◽  
Calibration Model ◽  
Radiometric Calibration ◽  
Relative Deviation ◽  
Transmission Process ◽  
Radiation Transmission ◽  
Polarimetric Imaging ◽  
Imaging Detection

In this paper, a new on-orbit polarization calibration method for the multichannel polarimetric camera is presented. A polarization calibration model for the polarimetric camera is proposed by taking analysis of the polarization radiation transmission process. In order to get the polarization parameters in the calibration model, an on-orbit measurement scheme is reported, which uses a solar diffuser and a built-in rotatable linear analyzer. The advantages of this scheme are sharing the same calibration assembly with the radiometric calibration and acquiring sufficient polarization accuracy. The influence of the diffuser for the measurement is analyzed. By using a verification experiment, the proposed method can achieve on-orbit polarization calibration. The experimental results show that the relative deviation for the measured degree of linear polarization is 0.8% at 670 nm, which provides a foundation for the accurate application of polarimetric imaging detection.

scholarly journals Accurate Calibration of a Self-Developed Vehicle-Borne LiDAR Scanning System

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Ming Guo ◽  
Bingnan Yan ◽  
Tengfei Zhou ◽  
Deng Pan ◽  
Guoli Wang
Keyword(s):  
Point Cloud ◽  
Laser Scanner ◽  
Measurement Data ◽  
Point Clouds ◽  
Calibration Method ◽  
Linear Interpolation ◽  
Measurement Unit ◽  
Scanning System ◽  
High Precision Measurement ◽  
Distance Ratio

To obtain high-precision measurement data using vehicle-borne light detection and ranging (LiDAR) scanning (VLS) systems, calibration is necessary before a data acquisition mission. Thus, a novel calibration method based on a homemade target ball is proposed to estimate the system mounting parameters, which refer to the rotational and translational offsets between the LiDAR sensor and inertial measurement unit (IMU) orientation and position. Firstly, the spherical point cloud is fitted into a sphere to extract the coordinates of the centre, and each scan line on the sphere is fitted into a section of the sphere to calculate the distance ratio from the centre to the nearest two sections, and the attitude and trajectory parameters of the centre are calculated by linear interpolation. Then, the real coordinates of the centre of the sphere are calculated by measuring the coordinates of the reflector directly above the target ball with the total station. Finally, three rotation parameters and three translation parameters are calculated by two least-squares adjustments. Comparisons of the point cloud before and after calibration and the calibrated point clouds with the point cloud obtained by the terrestrial laser scanner show that the accuracy significantly improved after calibration. The experiment indicates that the calibration method based on the homemade target ball can effectively improve the accuracy of the point cloud, which can promote VLS development and applications.

scholarly journals Radiometric Calibration for Incidence Angle, Range and Sub-Footprint Effects on Hyperspectral LiDAR Backscatter Intensity

2020 ◽  
Vol 12 (17) ◽  
pp. 2855
Author(s):  
Changsai Zhang ◽  
Shuai Gao ◽  
Wang Li ◽  
Kaiyi Bi ◽  
Ni Huang ◽  
...  
Keyword(s):  
Near Infrared ◽  
Spatial Information ◽  
Incidence Angle ◽  
Incident Angle ◽  
Calibration Method ◽  
Correction Method ◽  
Intensity Data ◽  
Radiometric Calibration ◽  
Backscatter Intensity ◽  
Reference Target

Terrestrial hyperspectral LiDAR (HSL) sensors could provide not only spatial information of the measured targets but also the backscattered spectral intensity signal of the laser pulse. The raw intensity collected by HSL is influenced by several factors, among which the range, incidence angle and sub-footprint play a significant role. Further studies on the influence of the range, incidence angle and sub-footprint are needed to improve the accuracy of backscatter intensity data as it is important for vegetation structural and biochemical information estimation. In this paper, we investigated the effects on the laser backscatter intensity and developed a practical correction method for HSL data. We established a laser ratio calibration method and a reference target-based method for HSL and investigated the calibration procedures for the mixed measurements of the effects of the incident angle, range and sub-footprint. Results showed that the laser ratio at the red-edge and near-infrared laser wavelengths has higher accuracy and simplicity in eliminating range, incident angle and sub-footprint effects and can significantly improve the backscatter intensity discrepancy caused by these effects.

scholarly journals Autonomous Mobile Ground Control Point Improves Accuracy of Agricultural Remote Sensing through Collaboration with UAV

Inventions ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 12
Author(s):  
Xiongzhe Han ◽  
J. Alex Thomasson ◽  
Tianyi Wang ◽  
Vaishali Swaminathan
Keyword(s):  
Remote Sensing ◽  
Control Point ◽  
Field Testing ◽  
Calibration Method ◽  
Large Field ◽  
Ground Control ◽  
Radiometric Calibration ◽  
Look Ahead ◽  
Data Collection Process ◽  
Actual Field

Ground control points (GCPs) are critical for agricultural remote sensing that require georeferencing and calibration of images collected from an unmanned aerial vehicles (UAV) at different times. However, the conventional stationary GCPs are time-consuming and labor-intensive to measure, distribute, and collect their information in a large field setup. An autonomous mobile GCP and a collaboration strategy to communicate with the UAV were developed to improve the efficiency and accuracy of the UAV-based data collection process. Prior to actual field testing, preliminary tests were conducted using the system to show the capability of automatic path tracking by reducing the root mean square error (RMSE) for lateral deviation from 34.3 cm to 15.6 cm based on the proposed look-ahead tracking method. The tests also indicated the feasibility of moving reflectance reference panels successively along all the waypoints without having detrimental effects on pixel values in the mosaicked images, with the percentage errors in digital number values ranging from −1.1% to 0.1%. In the actual field testing, the autonomous mobile GCP was able to successfully cooperate with the UAV in real-time without any interruption, showing superior performances for georeferencing, radiometric calibration, height calibration, and temperature calibration, compared to the conventional calibration method that has stationary GCPs.

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