• Title/Summary/Keyword: Cross Calibration

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OSMI ocean color products with updated cross-calibration coefficients

  • Lee S. G.;Kim Y. S.
    • Proceedings of the KSRS Conference
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    • pp.494-497
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    • 2004
  • To date the KOMPSAT OSMI(Ocean Scanning Multi-spectral Imager) data have been widely used in natural disaster monitoring such as Typhoon, Asian Dust, Red Tide, and Forest Fire. Quantitative analyses related to the marine ecosystem have been delayed because they require good quality of data through Cal/Val activities. To resolve such problem, KARI performed the OSMI crosscalibration study with SeaWiFS team. In this study, we will demonstrate the OSMI ocean color products with updated cross-calibration coefficients and compare them to the previous cross-calibration results.

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The Assessment of Cross Calibration/Validation Accuracy for KOMPSAT-3 Using Landsat 8 and 6S

  • Jin, Cheonggil;Choi, Chuluong
    • Korean Journal of Remote Sensing
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    • v.37 no.1
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    • pp.123-137
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    • 2021
  • In this study, we performed cross calibration of KOMPSAT-3 AEISS imaging sensor with reference to normalized pixels in the Landsat 8 OLI scenes of homogenous ROI recorded by both sensors between January 2014 and December 2019 at the Libya 4 PICS. Cross calibration is using images from a stable and well-calibrated satellite sensor as references to harmonize measurements from other sensors and/or characterize other sensors. But cross calibration has two problems; RSR and temporal difference. The RSR of KOMPSAT-3 and Landsat 8 are similar at the blue and green bands. But the red and NIR bands have a large difference. So we calculate SBAF of each sensor. We compared the SBAF estimated from the TOA Radiance simulation with KOMPSAT-3 and Landsat 8, the results displayed a difference of about 2.07~2.92% and 0.96~1.21% in the VIS and NIR bands. Before SBAF, Reflectance and Radiance difference was 0.42~23.23%. Case of difference temporal, we simulated by 6S and Landsat 8 for alignment the same acquisition time. The SBAF-corrected cross calibration coefficients using KOMPSAT-3, 6S and simulated Landsat 8 compared to the initial cross calibration without correction demonstrated a percentage difference in the spectral bands of about 0.866~1.192%. KOMPSAT-3 maximum uncertainty was estimated at 3.26~3.89%; errors due to atmospheric condition minimized to less than 1% (via 6S); Maximum deviation of KOMPSAT-3 DN was less than 1%. As the result, the results affirm that SBAF and 6s simulation enhanced cross-calibration accuracy.

Absolute Radiometric Calibration for KOMPSAT-3 AEISS and Cross Calibration Using Landsat-8 OLI

  • Ahn, Hoyong;Shin, Dongyoon;Lee, Sungu;Choi, Chuluong
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.35 no.4
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    • pp.291-302
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    • 2017
  • Radiometric calibration is a prerequisite to quantitative remote sensing, and its accuracy has a direct impact on the reliability and accuracy of the quantitative application of remotely sensed data. This paper presents absolute radiometric calibration of the KOMPSAT-3 (KOrea Multi Purpose SATellite-3) and cross calibration using the Landsat-8 OLI (Operational Land Imager). Absolute radiometric calibration was performed using a reflectance-based method. Correlations between TOA (Top Of Atmosphere) radiances and the spectral band responses of the KOMPSAT-3 sensors in Goheung, South Korea, were significant for multispectral bands. A cross calibration method based on the Landsat-8 OLI was also used to assess the two sensors using near simultaneous image pairs over the Libya-4 PICS (Pseudo Invariant Calibration Sites). The spectral profile of the target was obtained from EO-1 (Earth Observing-1) Hyperion data over the Libya-4 PICS to derive the SBAF (Spectral Band Adjustment Factor). The results revealed that the TOA radiance of the KOMPSAT-3 agree with Landsat-8 within 5.14% for all bands after applying the SBAF. The radiometric coefficient presented here appears to be a good standard for maintaining the optical quality of the KOMPSAT-3.

Cross-Calibration of Domestic Devices and GE Lunar Prodigy Advance Dual-Energy X-Ray Densitometer Devices for Bone Mineral Measurements (국산 이중에너지 방사선흡수 골밀도 장치와 GE Lunar Prodigy의 교차분석 식 도출에 관한 연구)

  • Kim, Jung-Su;Rho, Young-Hoon;Lee, In-Ju;Kim, Kyoung-Ah;Lee, In-Ja;Kim, Jung-Min
    • Journal of Radiation Industry
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    • v.11 no.1
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    • pp.27-31
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    • 2017
  • Reliable follow-up of bone mineral density (BMD) by dual energy X-ray absorptiometry (DXA) is essential in clinical practice. When there is a difference in the BMD values from DXA systems in the same patient, cross calibration equation is required for the reliable follow-up. Unfortunately, no equation is existed in BMD measure between GE Lunar Prodigy Advance (US, GE Healthcare; LPA) and Osteosys Dexxum T (Korea, Osteosys; ODT) DXA systems. In this study, we evaluate the agreement of BMD values between LPA and ODT and suggest the cross calibration equation using European spine phantom (ESP) with two systems. We performed BMD measurements using ten scans with ESP in each DXA systems. We compared BMD values and calculated cross calibration equation by linear regression analysis. The comparison between the LPA and ODT bone densitometers used the ESP. Compared to the ESP BMD values, ODT underestimated 14.36% and LPA overestimated 12.96%. The average of total BMD measurement values acquired with ODT were 21.44% lower than those from LPA. Cross-calibration equation for LPA and ODT was derived from ESP. We calculated simple cross calibration equation for LPA and ODT DXA systems. Cross-calibration equation is necessary for the reliable follow-up of BMD values in two different systems.

Automatic Cross-calibration of Multispectral Imagery with Airborne Hyperspectral Imagery Using Spectral Mixture Analysis

  • Yeji, Kim;Jaewan, Choi;Anjin, Chang;Yongil, Kim
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.33 no.3
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    • pp.211-218
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    • 2015
  • The analysis of remote sensing data depends on sensor specifications that provide accurate and consistent measurements. However, it is not easy to establish confidence and consistency in data that are analyzed by different sensors using various radiometric scales. For this reason, the cross-calibration method is used to calibrate remote sensing data with reference image data. In this study, we used an airborne hyperspectral image in order to calibrate a multispectral image. We presented an automatic cross-calibration method to calibrate a multispectral image using hyperspectral data and spectral mixture analysis. The spectral characteristics of the multispectral image were adjusted by linear regression analysis. Optimal endmember sets between two images were estimated by spectral mixture analysis for the linear regression analysis, and bands of hyperspectral image were aggregated based on the spectral response function of the two images. The results were evaluated by comparing the Root Mean Square Error (RMSE), the Spectral Angle Mapper (SAM), and average percentage differences. The results of this study showed that the proposed method corrected the spectral information in the multispectral data by using hyperspectral data, and its performance was similar to the manual cross-calibration. The proposed method demonstrated the possibility of automatic cross-calibration based on spectral mixture analysis.

Examination of Cross-calibration Between OSMI and SeaWiFS: Comparison of Ocean Color Products

  • Lee, Sun-Gu;Kim, Yong-Seung
    • Proceedings of the KSRS Conference
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    • pp.209-215
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    • 2002
  • Much effort has been made in the radiometric calibration of the ocean scanning multispectral imager (OSMI) since after the successful launch of KOMPSAT-1 in 1999. A series of calibration coefficients for OSMI detectors were obtained in collaboration with the NASA Sensor Intercomparison and Merger for Biological and Interdisciplinary (SIMBIOS) project office. In this study, we compare the OSMI level-2 products (e.g., chlorophyll-a concentration) calculated from the NASA cross-calibration coefficients with the SeaWiFS counterparts. Sample study areas are some of diagonostic data sites recommended by the SIMBIOS working group. We will present the preliminary results of this comparative study.

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Examination of Cross-calibration Between OSMI and SeaWiFS: Comparison of Ocean Color Products

  • Kim, Yong-Seung;Lee, Sun-Gu
    • Korean Journal of Remote Sensing
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    • v.19 no.3
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    • pp.201-208
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    • 2003
  • Much effort has been made in the radiometric calibration of the ocean scanning multispectral imager (OSMI) since after the successful launch of KOMPSAT-1 in 1999. A series of calibration coefficients for OSMI detectors were obtained in collaboration with the NASA Sensor Intercomparison and Merger for Biological and Interdisciplinary (SIMBIOS) project office. In this study, we ompare the OSMI level-2 products (e.g., chorophyll-a concentration) calculated from the NASA cross-calibration coefficients with the SeaWiFS counterparts. Sample study areas are some of diagonostic data sites recommended by the SIMBIOS working group. Results of this study show that the OSMl-derived chlorophyll-a concentration agrees well with the SeaWiFS counterpart in Case 1 water; however, differences become larger in Case 2 water.

Development of a Web-Based Program for Cross-Calibration and Record Management of Radiation Measuring Equipment

  • Park, So Hyun;Lee, Rena;Kim, Kyubo;Ahn, Sohyun;Lim, Sangwook;Cho, Samju
    • Progress in Medical Physics
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    • v.30 no.2
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    • pp.59-63
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    • 2019
  • Purpose: To manage radiation measurement equipment, a web-based management program has been developed in this study. Materials and Methods: This program is based on a web service and Java Server Pages (JSP) and employs compatibility and accessibility. Results: The first step in the workflow has been designed to create accounts for each user or organization and to log in. The program consists of two parts: fields for listed instruments, and measurement information. The instruments for measuring radiation listed in this program are as follows: ionization chambers, survey meters, thermometers, barometers, electrometers, and phantoms. Instrument properties can be put in the recording fields and browsing for associated instruments can be performed. The main part of the program is the cross-calibration for each ion chamber. For instance, the ionization chamber to be used as a relative dosimeter can be registered by cross-calibration data with a reference chamber calibrated by an accredited laboratory. This program supports methods using the central axis transfer theory for cross-calibration for the ionization chambers. The reference and field ionization chambers were placed in a solid water phantom along the beam central axis at two different depths, and then the positions were switched. Each measured value was used for calculating the cross-calibration factor. Conclusions: Because many instruments are used and managed in radiation oncology departments, systematic, traceable recording is very important. The web-based program developed in this study is expected to be used effectively in the maintenance of radiation measurement instruments.

An Empirical Validation Study for Calibration Verification in TDM Test (검량보정 검증의 실험적 적합성에 대한 연구 -치료적 약물검사를 중심으로-)

  • Chang, Sang-Wu;Kim, Nam-Yong;Choi, Ho-Sung;Park, Yong-Won;Chu, Gyung-Bok;Yun, Keun-Young;Park, Byung-Ok
    • Korean Journal of Clinical Laboratory Science
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    • v.37 no.1
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    • pp.1-7
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    • 2005
  • The purpose of this study was to verify (i) a consistent calibration verification for the assessment of method linearity and (ii) calibration agreement with calibration settings. We validated calibration verification through method linearity with different lot number of individual calibrators that span the working range for 9 tests except salicylate with control sample in test. We evaluated that it covered broad analyte range to assay from near zero to the top of the measuring range with 5 or 6 points every three times for 10 analytes in TDM test. Target values were plotted on X-axis with assigned or observed values on the Y-axis. Working range were as follows. Calibration verification of the measuring range (maximum to minimum values) has been validated asetaminophen 0.1 to $304.6_{\mu}g/mL$, salicylate 0 to $1005_{\mu}g/mL$, valproic acid 3.2 to $154.19_{\mu}g/mL$, digoxin 0.17 to 5.65 ng/mL, vancomycine 1.3 to $80.51_{\mu}g/mL$, carbarmazepine 0.1 to $22.3_{\mu}g/mL$, phenytonin 0.6 to $40.21_{\mu}g/mL$, theophyline 0.2 to $40.21_{\mu}g/mL$, primidone 0 to $24.07_{\mu}g/mL$, phenobarbital 0.6 to $60.0_{\mu}g/mL$. Drawing a straight line through five or six points of these data showed good linearity. We are sure that it is important to assess the calibration verification of a test method to ascertain the lowest and highest test results that are reliable.

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Development of Calibration Jet System for Calibrating a Flow Sensor (유동센서 보정용 캘리브레이션 제트 시스템 개발)

  • Chang, J.W.;Byun, Y.H.
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.11 no.1
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    • pp.41-55
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    • 2003
  • A calibration jet system using separate blower is developed to calibrate a flow sensor effectively. Designed open circuit type mini calibration jet system, which has the dimension of $0.5m(W){\times}1.17m(H)$ is small compared with conventional calibration jet systems. The exit of nozzle has exchangeable contractions with a cross section area of $38.5cm^2$ , and a cross section area of $113.1cm^2$, respectively. The ranges of wind speed at exit of exchangeable nozzles are $7.5{\sim}42\;m/s$ and $1.8{\sim}16.5\;m/s$, respectively. The input power for the high pressure blower is 1.18kW. The turning vanes for corner was rolled flat plate parallel to the flow direction. The flow conditioning screen was located immediately downstream of the wide-angle diffuser. The honeycomb and two flow conditioning screens were located in the stagnation chamber. From the economical point of view and the simplicity of the calibration jet system set up and handling, it can be said that the developed calibration jet system is an effective calibration jet system. This system can also be used to calibrate the flow sensor with high resolution.

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