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 Polarization Radiometric Calibration in Laboratory for a Channeled Spectropolarimeter

2020 ◽  
Vol 10 (22) ◽  
pp. 8295
Author(s):  
Wenhe Xing ◽  
Xueping Ju ◽  
Jian Bo ◽  
Changxiang Yan ◽  
Bin Yang ◽  
...  
Keyword(s):  
Optical System ◽  
Measurement Accuracy ◽  
Calibration Method ◽  
Stokes Parameters ◽  
Calibration Coefficient ◽  
Calibration Model ◽  
Radiometric Calibration ◽  
Reconstruction Methods ◽  
Proposed Model ◽  
Alignment Errors

The process of radiometric calibration would be coupled with the polarization properties of an optical system for spectropolarimetry, which would have significant influences on reconstructed Stokes parameters. In this paper, we propose a novel polarization radiometric calibration model that decouples the radiometric calibration coefficient and polarization properties of an optical system. The alignment errors of the polarization module and the variation of the retardations at different fields of view are considered and calibrated independently. According to these calibration results, the input Stokes parameters at different fields of view can be reconstructed accurately through the proposed model. Simulations are performed for the presented calibration and reconstruction methods, which indicate that the measurement accuracy of polarization information is improved compared with the traditional undecoupled calibration method.

Analysis and Model of SAR Radiometric Calibration in Near-Space

2013 ◽  
Vol 321-324 ◽  
pp. 842-846
Author(s):  
Song Tian ◽  
Jian She Song ◽  
Tie Jian Yang ◽  
Lian Feng Wang ◽  
Bao Shun Zhou
Keyword(s):  
Experimental Data ◽  
Calibration Method ◽  
Synthetic Aperture ◽  
Calibration Model ◽  
Radiometric Calibration ◽  
Backscattering Coefficient ◽  
Important Work ◽  
Work Related ◽  
Near Space ◽  
The Difference

Radiometric calibration of synthetic aperture radar (SAR) is an important work related to pixel values and the backscattering coefficient of ground targets. With a consideration of the difference between near space and spaceborne, airborne platforms, this paper proposes the radiometric calibration method which is applicable to near space platform. A radiometric calibration model of near space SAR is established, and it is analyzed and validated by experimental data.

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 Thermal Modeling and Calibration Method in Complex Temperature Field for Single-Axis Rotational Inertial Navigation System

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 384 ◽  
Author(s):  
Zihui Wang ◽  
Xianghong Cheng ◽  
Jingjing Du
Keyword(s):  
Temperature Field ◽  
Inertial Navigation ◽  
Calibration Method ◽  
Measurement Unit ◽  
Calibration Model ◽  
Navigation Systems ◽  
Moving Vehicle ◽  
Temperature Change Rate ◽  
Environment Temperature ◽  
Complex Temperature

Single-axis rotational inertial navigation systems (single-axis RINSs) are widely used in high-accuracy navigation because of their ability to restrain the horizontal axis errors of the inertial measurement unit (IMU). The IMU errors, especially the biases, should be constant during each rotation cycle that is to be modulated and restrained. However, the temperature field, consisting of the environment temperature and the power heating of single-axis RINS, affects the IMU performance and changes the biases over time. To improve the precision of single-axis RINS, the change of IMU biases caused by the temperature should be calibrated accurately. The traditional thermal calibration model consists of the temperature and temperature change rate, which does not reflect the complex temperature field of single-axis RINS. This paper proposed a multiple regression method with a temperature gradient in the model, and in order to describe the complex temperature field thoroughly, a BP neural network method is proposed with consideration of the coupled items of the temperature variables. Experiments show that the proposed methods outperform the traditional calibration method. The navigation accuracy of single-axis RINS can be improved by up to 47.41% in lab conditions and 65.11% in the moving vehicle experiment, respectively.

scholarly journals On-Orbit Geometric Calibration from the Relative Motion of Stars for Geostationary Cameras

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6668
Author(s):  
Linyi Jiang ◽  
Xiaoyan Li ◽  
Liyuan Li ◽  
Lin Yang ◽  
Lan Yang ◽  
...  
Keyword(s):  
Relative Motion ◽  
Calibration Method ◽  
System Structure ◽  
Calibration Model ◽  
Control Points ◽  
Penetration Process ◽  
Geometric Calibration ◽  
Positioning Errors ◽  
Ground Control Points ◽  
Motion Transformation

Affected by the vibrations and thermal shocks during launch and the orbit penetration process, the geometric positioning model of the remote sensing cameras measured on the ground will generate a displacement, affecting the geometric accuracy of imagery and requiring recalibration. Conventional methods adopt the ground control points (GCPs) or stars as references for on-orbit geometric calibration. However, inescapable cloud coverage and discontented extraction algorithms make it extremely difficult to collect sufficient high-precision GCPs for modifying the misalignment of the camera, especially for geostationary satellites. Additionally, the number of the observed stars is very likely to be inadequate for calibrating the relative installations of the camera. In terms of the problems above, we propose a novel on-orbit geometric calibration method using the relative motion of stars for geostationary cameras. First, a geometric calibration model is constructed based on the optical system structure. Then, we analyze the relative motion transformation of the observed stars. The stellar trajectory and the auxiliary ephemeris are used to obtain the corresponding object vector for correcting the associated calibration parameters iteratively. Experimental results evaluated on the data of a geostationary experiment satellite demonstrate that the positioning errors corrected by this proposed method can be within ±2.35 pixels. This approach is able to effectively calibrate the camera and improve the positioning accuracy, which avoids the influence of cloud cover and overcomes the great dependence on the number of the observed stars.

scholarly journals Development of multivariate calibration method for simultaneous determination of nickel, lead and zinc in tap water

2015 ◽  
Vol 18 (2) ◽  
pp. 145-151
Author(s):  
Chau Minh Huynh ◽  
Thu Du Ly ◽  
Thach Thai Pham ◽  
Tran Thi Bao Pham ◽  
Minh Khanh Duong ◽  
...  
Keyword(s):  
Simultaneous Determination ◽  
Absorption Spectra ◽  
Multivariate Calibration ◽  
Tap Water ◽  
Calibration Method ◽  
Calibration Model ◽  
Determination Of Nickel ◽  
Lead And Zinc ◽  
Nickel Lead

Conventional spectrophotometric methods for simultaneous determination of nickel, lead and zinc in forms of complexes with a reagent is not feasible due to the overlap of their absorption spectra. A multivariate calibration method was used to overcome this problem. In this study, the calibration model was constructed based on absorption spectra of 30 mixture standards in the range from 490 to 600 nm. Factors influencing experimental results such as amount of reagents, pH, and color development time were optimized. The standard calibration ranges for determination of nickel, lead and zinc were found at 0.5-5 ppm. The method was applied for determination of these ions in tap water samples at ppm level, with recoveries (and RSD) of nickel, lead and zinc were 103.3 % (3.0 %), 74.9 % (11.5 %) and 104.6 % (4.6 %), respectively.

scholarly journals The Addition of N-Butanol in Ethanol-Isooctane Mixture to Reduce Vapor Pressure of Oxygenated-Gasoline Blend

2017 ◽  
Vol 17 (3) ◽  
pp. 500 ◽  
Author(s):  
Rendra Panca Anugraha ◽  
Zul Akbar Andi Picunang ◽  
Annas Wiguno ◽  
Rizky Tetrisyanda ◽  
Kuswandi Kuswandi ◽  
...  
Keyword(s):  
Experimental Data ◽  
Ternary System ◽  
Vapor Pressure ◽  
Binary Systems ◽  
Experimental Results ◽  
Ideal Solution ◽  
Positive Deviation ◽  
Relative Deviation ◽  
Wilson Model ◽  
Binary Parameter

In this work, vapor pressure of binary systems for isooctane + ethanol, isooctane + n-butanol and ethanol + n-butanol and ternary system for isooctane + ethanol + n-butanol were measured in the temperature range from 313.15 to 318.15 K using the inclined ebulliometer. The experimental results showed that the existence of n-butanol in isooctane decreases the vapor pressure of mixture, while increasing n-butanol fraction in ternary isooctane-ethanol-n-butanol mixture decreased vapor pressure of mixture. Experimental data for binary systems studied were correlated with Wilson, NRTL and UNIQUAC models with average relative deviation (ARD) of 3.5%. The optimized binary parameter pairs obtained in this work were used to estimate the ternary system. The Wilson model gave the best performance for estimation of ternary system with ARD of 5.4%. All systems studied showed non-ideal solution with positive deviation from Raoult’s law.

scholarly journals Prediction of Caffeine Content in Liberica Coffee Green Bean by NIR Spectroscopy Using Kubelka-Munk Model

2020 ◽  
Vol 7 (3) ◽  
pp. 119
Author(s):  
Ei Mon Kyaw ◽  
I Wayan Budiastra ◽  
Sutrisno Sutrisno ◽  
Samsudin Samsudin ◽  
Dheni Mita Mala
Keyword(s):  
Chemical Analysis ◽  
Nir Spectroscopy ◽  
Consumer Preference ◽  
Data Transformation ◽  
Calibration Method ◽  
Partial Least Square ◽  
Green Bean ◽  
Calibration Model ◽  
Second Derivative ◽  
Caffeine Content

<p>Liberica is one of coffee species that is becoming popular and increasingly in demand in present days due to its unique characteristics. Caffeine is one of the important coffee quality parameter which determines the coffee flavor, consumer preference and market price. Caffeine content is usually analyzed by chemical method which is destructive, time consuming, expensive and involving a lot of procedures. NIR Spectroscopy is one of the non-destructive techniques to overcome these disadvantages. This study was conducted at the Department of Mechanical and Biosystem Engineering, IPB University for NIR measurement and the Center of Agro-based Industry (BBIA), Bogor for chemical analysis from August to November 2019. The study aimed to determine the best calibration model for the prediction of caffeine content in Liberica coffee green bean powder. In this study, FT-NIRS in the wavelength of 1000-2500 nm was used for NIR measurement and HPLC tool was used for chemical analysis. Kubelka-Munk (K/S) and Absorbance (Log 1/R) were used as data transformation, whereas Standard Normal Variance (SNV) and Second derivative of Savitzky-Golay (dg2) as data pretreatment. In addition, Partial Least Square (PLS) and Multiple Linear Regression (MLR) were applied for multivariate calibration method. The best calibration model for the prediction of caffeine content of Liberica coffee green bean powder was obtained by the spectral data pretreated with second derivative of Savitzky-Golay (dg2) and Kubelka-Munk data transformation using PLS calibration method with the results of r = 0.90, RPD = 2.24, CV = 2.01%.</p>

A Rapid Field Calibrating Method for MIMU

2011 ◽  
Vol 80-81 ◽  
pp. 1140-1144
Author(s):  
Yu Bao Fan ◽  
Jie Li ◽  
Bo Wang ◽  
Xiao Chun Tian ◽  
Jun Liu
Keyword(s):  
Inertial Measurement Unit ◽  
Operation Time ◽  
Calibration Method ◽  
Least Square ◽  
Measurement Unit ◽  
Calibration Model ◽  
Time Saving ◽  
Inertial Measurement ◽  
Field Calibration ◽  
Calibration Program

When the Micro Inertial Measurement Unit is been placed randomly in the case of stationary, the sum vectors that measured by the inertial devices configured orthogonally along three axis, are constant vectors. In view of the above objective facts, a field calibration method of micro inertial measurement unit was proposed. On the base of the establishment and optimization of calibration model, all parameters to be calibrated can be obtained through the least square by the ellipsoid fitting, with the result of high-precision field calibration for micro inertial measurement unit. Finally, a filed calibration program for micro inertial measurement unit is scheduled reasonably. The experiment results show that the method has such characteristics such as easily-operation, time-saving, higher calibration accuracy, and not depending on the baseline direction and datum offered by precision instruments. Especially, it fits for inertial measurement systems which work short time and ask for high accuracy. In addition, it can also significantly increase the measurement accuracy of micro inertial measurement system in practical application.

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