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Journal articles on the topic 'Calibration methods'

Author: Grafiati

Published: 4 June 2021

Last updated: 27 April 2022

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1

Chen, Gang, Hua Chen, Yu Bo Guo, and Dong Ye. "The Comparison of Two Stereo Vision Sensor Calibration Methods." Advanced Materials Research 317-319 (August 2011): 397–400. http://dx.doi.org/10.4028/www.scientific.net/amr.317-319.397.

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This paper presents and comparison two stereo vision sensor calibration methods: Volume template based calibration method and the calibration based on virtual stereo pattern. First method use a premade volume template. Second method use a group of random spatial points that are formed by an infrared LED moved with the probe of CMM. Two methods adopt an ideal pin-hole model that ignores the nonlinear distortion of the cameras. Through compare two calibratioin methods, we can draw conclusion that the first method can be applide to stereo sensor calibration in measurement field and the second method could gain higher calibrating precision.

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Ona, Egil, Valerie Mazauric, and Lars Nonboe Andersen. "Calibration methods for two scientific multibeam systems." ICES Journal of Marine Science 66, no. 6 (May 8, 2009): 1326–34. http://dx.doi.org/10.1093/icesjms/fsp125.

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Abstract Ona, E., Mazauric, V., and Andersen, L. N. 2009. Calibration methods for two scientific multibeam systems. – ICES Journal of Marine Science, 66: 1326–1334. The new Simrad scientific multibeam systems, the MS70 sonar and the ME70 echosounder, each transmit over many electronically formed beams with centre frequencies spanning from 70 to 120 kHz. Calibrations of these systems are therefore more complex than for conventional split-beam echosounder systems. Two large tungsten-carbide spheres (75 and 84 mm diameter) were designed and manufactured to facilitate accurate field calibrations over the entire operational bandwidth. These are heavy and therefore stable when suspended beneath a ship, and have target strengths much larger than those of biological targets potentially within the measurement volume. This paper presents procedures for calibrating each system in the field and the results from two such experiments. Detailed inspections of the results for individual beams indicate that minor adjustments in the described procedures might further improve the reported calibration accuracy.

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Jessen, W., S. Wilbert, B. Nouri, N. Geuder, and H. Fritz. "Calibration methods for rotating shadowband irradiometers and evaluation of calibration duration." Atmospheric Measurement Techniques Discussions 8, no. 10 (October 6, 2015): 10249–82. http://dx.doi.org/10.5194/amtd-8-10249-2015.

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Abstract. Resource assessment for Concentrated Solar Power (CSP) needs accurate Direct Normal Irradiance (DNI) measurements. An option for such measurement campaigns are Rotating Shadowband Irradiometers (RSIs) with a thorough calibration. Calibration of RSIs and Si-sensors in general is complex because of the inhomogeneous spectral response of such sensors and incorporates the use of several correction functions. A calibration for a given atmospheric condition and air mass might not work well for a different condition. This paper covers procedures and requirements for two calibration methods for the calibration of Rotating Shadowband Irradiometers. The necessary duration of acquisition of test measurements is examined in regard to the site specific conditions at Plataforma Solar de Almeria (PSA) in Spain. Data sets of several long-term calibration periods from PSA are used to evaluate the deviation of results from calibrations with varying duration from the long-term result. The findings show that seasonal changes of environmental conditions are causing small but noticeable fluctuation of calibration results. Certain periods (i.e. November to January and April to May) show a higher likelihood of particularly adverse calibration results. These effects can partially be compensated by increasing the inclusions of measurements from outside these periods. Consequently, the duration of calibrations at PSA can now be selected depending on the time of the year in which measurements are commenced.

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Silvestrov, I. S., V. F. Fateev, and R. A. Davlatov. "Methods of metrological support of space gravity gradiometers." Izmeritel`naya Tekhnika, no. 1 (January 2020): 5–10. http://dx.doi.org/10.32446/0368-1025it.2020-1-5-10.

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An analysis is made of the known methods for calibrating and evaluating the parameters of implemented space gradiometers. There are 4 main stages: laboratory assessment of amendments, assessment of amendments during operation, assessment of amendments from independent data, calibration. A description of each step is provided. Two methods for calibrating space gradiometers are proposed: based on a complex of calibration sites and an onboard stand. The principles of building elements of a complex of calibration sites are investigated and their structure is formed. The analysis of the possibility of using the onboard mass on board the spacecraft for calibrating the space gradiometer is carried out. The main parameters of the onboard stand are highlighted. Scope: determination of metrological characteristics of space gravitational gradiometers.

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5

Jessen, Wilko, Stefan Wilbert, Bijan Nouri, Norbert Geuder, and Holger Fritz. "Calibration methods for rotating shadowband irradiometers and optimizing the calibration duration." Atmospheric Measurement Techniques 9, no. 4 (April 12, 2016): 1601–12. http://dx.doi.org/10.5194/amt-9-1601-2016.

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Abstract. Resource assessment for concentrated solar power (CSP) needs accurate direct normal irradiance (DNI) measurements. An option for such measurement campaigns is the use of thoroughly calibrated rotating shadowband irradiometers (RSIs). Calibration of RSIs and Si-sensors is complex because of the inhomogeneous spectral response of these sensors and incorporates the use of several correction functions. One calibration for a given atmospheric condition and air mass might not be suitable under different conditions. This paper covers procedures and requirements of two calibration methods for the calibration of rotating shadowband irradiometers. The necessary duration of acquisition of test measurements is examined with regard to the site-specific conditions at Plataforma Solar de Almería (PSA) in Spain. Seven data sets of long-term test measurements were collected. For each data set, calibration results of varying durations were compared to its respective long-term result. Our findings show that seasonal changes of environmental conditions are causing small but noticeable fluctuation of calibration results. Calibration results within certain periods (i.e. November to January and April to May) show a higher likelihood of deviation. These effects can partially be attenuated by including more measurements from outside these periods. Consequently, the duration of calibrations at PSA can now be selected depending on the time of year in which measurements commence.

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6

Sun, Cong, Haibo Liu, Mengna Jia, and Shengyi Chen. "Review of Calibration Methods for Scheimpflug Camera." Journal of Sensors 2018 (2018): 1–15. http://dx.doi.org/10.1155/2018/3901431.

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The Scheimpflug camera offers a wide range of applications in the field of typical close-range photogrammetry, particle image velocity, and digital image correlation due to the fact that the depth-of-view of Scheimpflug camera can be greatly extended according to the Scheimpflug condition. Yet, the conventional calibration methods are not applicable in this case because the assumptions used by classical calibration methodologies are not valid anymore for cameras undergoing Scheimpflug condition. Therefore, various methods have been investigated to solve the problem over the last few years. However, no comprehensive review exists that provides an insight into recent calibration methods of Scheimpflug cameras. This paper presents a survey of recent calibration methods of Scheimpflug cameras with perspective lens, including the general nonparametric imaging model, and analyzes in detail the advantages and drawbacks of the mainstream calibration models with respect to each other. Real data experiments including calibrations, reconstructions, and measurements are performed to assess the performance of the models. The results reveal that the accuracies of the RMM, PLVM, PCIM, and GNIM are basically equal, while the accuracy of GNIM is slightly lower compared with the other three parametric models. Moreover, the experimental results reveal that the parameters of the tangential distortion are likely coupled with the tilt angle of the sensor in Scheimpflug calibration models. The work of this paper lays the foundation of further research of Scheimpflug cameras.

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7

Bhatt, Rajendra, David R. Doelling, Benjamin R. Scarino, Arun Gopalan, Conor O. Haney, Patrick Minnis, and Kristopher M. Bedka. "A Consistent AVHRR Visible Calibration Record Based on Multiple Methods Applicable for the NOAA Degrading Orbits. Part I: Methodology." Journal of Atmospheric and Oceanic Technology 33, no. 11 (November 2016): 2499–515. http://dx.doi.org/10.1175/jtech-d-16-0044.1.

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AbstractThe 35-yr NOAA Advanced Very High Resolution Radiometer (AVHRR) observation record offers an excellent opportunity to study decadal climate variability, provided that all participating AVHRR instruments are calibrated on a consistent radiometric scale. Because of the lack of onboard calibration systems, the solar imaging channels of the AVHRR must be vicariously calibrated using invariant Earth targets as a calibrated reference source. The greatest challenge in calibrating the AVHRR dataset is the orbit degradation of the NOAA satellites, which eventually drift into a terminator orbit several years after launch. Therefore, the invariant targets must be characterized over the full range of solar zenith angles (SZAs) sampled by the satellite instrument.This study outlines a multiple invariant Earth target calibration approach specifically designed to account for the degrading NOAA orbits. The desert, polar ice, and deep convective cloud (DCC) invariant targets are characterized over all observed SZAs using NOAA-16 AVHRR measurements, which are referenced to the Aqua MODIS Collection 6 calibration via direct transfer of the MODIS calibration to the NOAA-16 AVHRR instrument using simultaneous nadir overpass (SNO) observations over the North Pole. The multiple invariant target calibrations are combined using the inverse of their temporal variance to optimize the resulting calibration stability. The NOAA-18 AVHRR gains derived using the desert, polar ice, and DCC targets, as well as from SNO, were found consistent within 1%, thereby validating that the Aqua MODIS calibration is effectively transferred to the reference calibration targets. The companion paper, Part II, applies the methodology across the AVHRR record to derive the sensor-specific calibration coefficients.

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Mlcek, Jiri, Lukas Dvorak, Kvetoslava Sustova, and Katarzyna Szwedziak. "Accuracy of the FT-NIR Method in Evaluating the Fat Content of Milk Using Calibration Models Developed for the Reference Methods According to Röse-Gottlieb and Gerber." Journal of AOAC INTERNATIONAL 99, no. 5 (September 1, 2016): 1305–9. http://dx.doi.org/10.5740/jaoacint.16-0107.

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Abstract The study examined the effect of the choice of reference method on the functionality and reliability of calibrations in near-IR (NIR) spectroscopy intended for measuring the fat content in raw cow's milk. The fat content in the milk samples was evaluated using methods according to either Röse-Gottlieb or Gerber. The same samples were then subjected to analysis on an Antaris FT-NIR spectrometer. Using a partial least-squares algorithm, calibration models were created for both methods from the values measured. The calibration models show very good values of standard error of calibration: 0.133 for the Gerber method and 0.095 for the Röse-Gottlieb method. These calibrations were subsequently used to analyze 30 new samples of cow's milk of undefined fat content, and the differences in the values were evaluated using statistical paired t-test to a median value at a probability level of α = 0.05. No statistically significant differences were found. It was revealed that the reference method used for calibrating the device evaluating the fat content in raw cow's milk has no effect on the functionality and reliability of the calibration model.

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9

Taylor, Douglas C. A., Vivek Pawar, Denise Kruzikas, Kristen E. Gilmore, Ankur Pandya, Rowan Iskandar, and Milton C. Weinstein. "Methods of Model Calibration." PharmacoEconomics 28, no. 11 (November 2010): 995–1000. http://dx.doi.org/10.2165/11538660-000000000-00000.

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10

Emery, Keith A., and Carl R. Osterwald. "Solar cell calibration methods." Solar Cells 27, no. 1-4 (October 1989): 445–53. http://dx.doi.org/10.1016/0379-6787(89)90054-9.

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11

Parczewski, A., and G. Kateman. "Calibration of titration methods." Fresenius' Journal of Analytical Chemistry 342, no. 1-2 (1992): 10–14. http://dx.doi.org/10.1007/bf00321681.

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12

Lin, Psang D., and Chi K. Sung. "Comparing two new camera calibration methods with traditional pinhole calibrations." Optics Express 15, no. 6 (2007): 3012. http://dx.doi.org/10.1364/oe.15.003012.

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13

Kiedron, P. W., and J. J. Michalsky. "Non-parametric and least squares Langley plot methods." Atmospheric Measurement Techniques 9, no. 1 (January 25, 2016): 215–25. http://dx.doi.org/10.5194/amt-9-215-2016.

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Abstract. Langley plots are used to calibrate sun radiometers primarily for the measurement of the aerosol component of the atmosphere that attenuates (scatters and absorbs) incoming direct solar radiation. In principle, the calibration of a sun radiometer is a straightforward application of the Bouguer–Lambert–Beer law V = V0e−τ ⋅ m, where a plot of ln(V) voltage vs. m air mass yields a straight line with intercept ln(V0). This ln(V0) subsequently can be used to solve for τ for any measurement of V and calculation of m. This calibration works well on some high mountain sites, but the application of the Langley plot calibration technique is more complicated at other, more interesting, locales. This paper is concerned with ferreting out calibrations at difficult sites and examining and comparing a number of conventional and non-conventional methods for obtaining successful Langley plots. The 11 techniques discussed indicate that both least squares and various non-parametric techniques produce satisfactory calibrations with no significant differences among them when the time series of ln(V0)'s are smoothed and interpolated with median and mean moving window filters.

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Kiedron, P. W., and J. J. Michalsky. "Non-parametric and least squares Langley plot methods." Atmospheric Measurement Techniques Discussions 8, no. 4 (April 27, 2015): 4191–218. http://dx.doi.org/10.5194/amtd-8-4191-2015.

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Abstract. Langley plots are used to calibrate sun radiometers primarily for the measurement of the aerosol component of the atmosphere that attenuates (scatters and absorbs) incoming direct solar radiation. In principle, the calibration of a sun radiometer is a straightforward application of the Bouguer–Lambert–Beer law V=V>/i>0e−τ ·m, where a plot of ln (V) voltage vs. m air mass yields a straight line with intercept ln (V0). This ln (V0) subsequently can be used to solve for τ for any measurement of V and calculation of m. This calibration works well on some high mountain sites, but the application of the Langley plot calibration technique is more complicated at other, more interesting, locales. This paper is concerned with ferreting out calibrations at difficult sites and examining and comparing a number of conventional and non-conventional methods for obtaining successful Langley plots. The eleven techniques discussed indicate that both least squares and various non-parametric techniques produce satisfactory calibrations with no significant differences among them when the time series of ln (V0)'s are smoothed and interpolated with median and mean moving window filters.

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Franken, Arnoud R. C., and Paul C. Ivey. "Accelerating the Calibration of Multihole Pressure Probes by Applying Advanced Computational Methods." Journal of Turbomachinery 127, no. 3 (July 1, 2005): 425–30. http://dx.doi.org/10.1115/1.1791285.

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The miniature multihole pneumatic pressure probe is widely regarded as a cost-effective, easy-to-use, and accurate method for performing two- or three-dimensional flow field measurements in turbomachinery. The major downside to the use of these probes is that the influence of fabrication imperfections on probe characteristics necessitates an extensive and highly time-intensive and, therefore, costly calibration of each individual probe. Unless these probes can be fabricated to such standards that make individual probe calibrations superfluous, the only way to significantly reduce the time and costs associated with probe calibration is to shorten the calibration process. The latter is only possible if all essential information can be obtained from less calibration data. This paper describes an approach to the calibration of a series of multihole pressure probes in which advanced computational methods are used to make this possible. By exploiting the key features of a probe’s characteristic this approach requires only a fraction of the size of a conventional calibration database for the accurate modeling of the relationships between port pressures and flow conditions. As a result, calibration time and costs can be reduced without the sacrifice of quality.

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16

Lieberman, Alvin. "Calibrations Requirements and Methods for Liquid-Borne Particle Counters." Journal of the IEST 31, no. 3 (May 1, 1988): 34–36. http://dx.doi.org/10.17764/jiet.1.31.3.063155412224288w.

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This paper describes present U.S. practices for calibrating optical liquid-borne particle counters (APCs). Operation of these instruments is described briefly for both light extinction and scattering instruments in order to help the reader understand why empirical calibration is necessary. Calibration requirements are pointed out in terms of the need to verify both particle sizing and particle counting accuracy. Two calibration methods are currently used in the U.S. One is based on size and count response to a suspension of presized isotropic latex spheres. The other is based on APC adjustment to match the stated size distribution of a test dust polydisperse suspension at a specific concentration. Both methods are described and some advantages and problems are presented.

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17

Doelling, David R., Rajendra Bhatt, Benjamin R. Scarino, Arun Gopalan, Conor O. Haney, Patrick Minnis, and Kristopher M. Bedka. "A Consistent AVHRR Visible Calibration Record Based on Multiple Methods Applicable for the NOAA Degrading Orbits. Part II: Validation." Journal of Atmospheric and Oceanic Technology 33, no. 11 (November 2016): 2517–34. http://dx.doi.org/10.1175/jtech-d-16-0042.1.

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AbstractConsistent cross-sensor Advanced Very High Resolution Radiometer (AVHRR) calibration coefficients are determined using desert, polar ice, and deep convective cloud (DCC) invariant Earth targets. The greatest AVHRR calibration challenge is the slow orbit degradation of the host satellite, which precesses toward a terminator orbit. This issue is solved by characterizing the invariant targets with NOAA-16 AVHRR observed radiances that have been referenced to the Aqua Moderate Resolution Imaging Spectrometer (MODIS) calibration using simultaneous nadir overpass (SNO) observations. Another benefit of the NOAA-16 invariant target–modeled reflectance method is that, because of the similarities among the AVHRR spectral response functions, a smaller spectral band adjustment factor is required than when establishing calibrations relative to a non-AVHRR reference instrument. The sensor- and band-specific calibration uncertainties, with respect to the calibration reference, are, on average, 2% and 3% for channels 1 and 2, respectively. The uncertainties are smaller for sensors that are in afternoon orbits, have longer records, and spend less time in terminator conditions.The multiple invariant targets referenced to Aqua MODIS (MITRAM) AVHRR calibration coefficients are evaluated for individual target consistency, compared against Aqua MODIS/AVHRR SNOs, and selected published calibration gains. The MITRAM and SNO relative calibration biases mostly agree to within 1% for channels 1 and 2, respectively. The individual invariant target and MITRAM sensor relative calibration biases are mostly consistent to within 1% and 2% for channels 1 and 2, respectively. The differences between the MITRAM and other published calibrations are mostly attributed to the reference instrument calibration differences.

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18

Wang, Xuguang, and Edward Red. "Robotic TCF and rigid-body calibration methods." Robotica 15, no. 6 (November 1997): 633–44. http://dx.doi.org/10.1017/s0263574797000763.

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For off-line programming to work, systematic methods must be developed to account for non-ideal performance of the parts and devices in the manufacturing cell. Although much of the literature focuses on robot inaccuracy, this paper considers practical methods for the tool control frame (TCF) calibration and rigid-body compensation required to close the inverse kinematics loop for target driven tasks.In contrast to contemporary estimation methods, a closed-form, easily automated, solution is introduced for calibrating the position and orientation (pose) of orthogonal end-effectors when the distal robot joint is revolute. This paper also considers methods for measuring and compensating the small rigid-body perturbations that result from non-repeatable part delivery systems or from geometric distortion. These methods are designed to eliminate rθ error from the rigid-body prediction and can be conducted in real-time. Without accurate TCF calibration and rigid-body compensation, even the most accurate robot will fail to complete an off-line programmed task if the task tolerances are stringent.

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Wang, Long, Yang Xu, and Xian Hong Li. "Calibration Methods of Proximate Analyzer." Advanced Materials Research 945-949 (June 2014): 2089–92. http://dx.doi.org/10.4028/www.scientific.net/amr.945-949.2089.

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Proximate analyzer is broadly used for determination of coal, so it is very important to evaluate its performance, orderly, the proximate analyzer is needed to be calibrated by metrology organizations. But there is no standard or regulation for proximate analyzer calibration in our country. On the basis of the function characteristics of proximate analyzer, the authors have suggested the calibration methods of temperature control performance, indication error and repeatability of ash and volatile, and the general technical requirement which includes appearance, insulation resistance, and insulation strength. The experimental results prove that this method can evaluate the performance of the proximate analyzer accurately and comprehensively.

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Castro, Claudia, Ernesto Octavio Lopez, and Guadalupe Elizabeth Morales. "Calibration Methods of Deception Detection." Psychology 05, no. 19 (2014): 2138–46. http://dx.doi.org/10.4236/psych.2014.519216.

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Wang, Long, and Yu Feng Xu. "Calibration Methods of Silicate Analyzer." Advanced Materials Research 1061-1062 (December 2014): 1008–10. http://dx.doi.org/10.4028/www.scientific.net/amr.1061-1062.1008.

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Silicate analyzer is broadly used for determination of silicate in water. It is very important to evaluate its performance and needed to be calibrated by metrology organizations. But there is no standard or regulation for silicate analyzer calibration in our country. The calibration methods of silicate analyzer was suggested on the basis of the function characteristics of the instrument. The experimental results prove that this method can evaluate the performance of silicate analyzer accurately and comprehensively.

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Bellio, Ruggero. "Likelihood Methods for Controlled Calibration." Scandinavian Journal of Statistics 30, no. 2 (June 2003): 339–53. http://dx.doi.org/10.1111/1467-9469.00334.

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23

Takeshita, Shunji. "Temperature Standards and Calibration Methods." Journal of Agricultural Meteorology 43, no. 2 (1987): 157–58. http://dx.doi.org/10.2480/agrmet.43.157.

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Boucher, Thomas, M. Darby Dyar, and Sridhar Mahadevan. "Proximal methods for calibration transfer." Journal of Chemometrics 31, no. 4 (April 2017): e2877. http://dx.doi.org/10.1002/cem.2877.

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Helland, Inge, and Knut Kvaal. "Neural Networks as Calibration Methods." NIR news 6, no. 3 (June 1995): 2–3. http://dx.doi.org/10.1255/nirn.301.

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Bringmann, B., J. P. Besuchet, and L. Rohr. "Systematic evaluation of calibration methods." CIRP Annals 57, no. 1 (2008): 529–32. http://dx.doi.org/10.1016/j.cirp.2008.03.114.

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Rueda, M., S. Martínez-Puertas, H. Martínez-Puertas, and A. Arcos. "Calibration methods for estimating quantiles." Metrika 66, no. 3 (December 12, 2006): 355–71. http://dx.doi.org/10.1007/s00184-006-0116-1.

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Kościelniak, Paweł. "Calibration methods in qualitative analysis." TrAC Trends in Analytical Chemistry 150 (May 2022): 116587. http://dx.doi.org/10.1016/j.trac.2022.116587.

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De Champlain, Andre F., Andre-Philippe Boulais, and Andrew Dallas. "Calibrating the Medical Council of Canada’s Qualifying Examination Part I using an integrated item response theory framework: a comparison of models and designs." Journal of Educational Evaluation for Health Professions 13 (January 20, 2016): 6. http://dx.doi.org/10.3352/jeehp.2016.13.6.

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Purpose: The aim of this research was to compare different methods of calibrating multiple choice question (MCQ) and clinical decision making (CDM) components for the Medical Council of Canada’s Qualifying Examination Part I (MCCQEI) based on item response theory. Methods: Our data consisted of test results from 8,213 first time applicants to MCCQEI in spring and fall 2010 and 2011 test administrations. The data set contained several thousand multiple choice items and several hundred CDM cases. Four dichotomous calibrations were run using BILOG-MG 3.0. All 3 mixed item format (dichotomous MCQ responses and polytomous CDM case scores) calibrations were conducted using PARSCALE 4. Results: The 2-PL model had identical numbers of items with chi-square values at or below a Type I error rate of 0.01 (83/3,499 or 0.02). In all 3 polytomous models, whether the MCQs were either anchored or concurrently run with the CDM cases, results suggest very poor fit. All IRT abilities estimated from dichotomous calibration designs correlated very highly with each other. IRT-based pass-fail rates were extremely similar, not only across calibration designs and methods, but also with regard to the actual reported decision to candidates. The largest difference noted in pass rates was 4.78%, which occurred between the mixed format concurrent 2-PL graded response model (pass rate= 80.43%) and the dichotomous anchored 1-PL calibrations (pass rate= 85.21%). Conclusion: Simpler calibration designs with dichotomized items should be implemented. The dichotomous calibrations provided better fit of the item response matrix than more complex, polytomous calibrations.

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Senn, J. A., J. P. Mills, P. E. Miller, C. Walsh, S. Addy, E. Loerke, and M. V. Peppa. "ON-SITE GEOMETRIC CALIBRATION OF THERMAL AND OPTICAL SENSORS FOR UAS PHOTOGRAMMETRY." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B1-2020 (August 6, 2020): 355–61. http://dx.doi.org/10.5194/isprs-archives-xliii-b1-2020-355-2020.

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Abstract. UAS imagery has become a widely used source of information in geomorphic research. When photogrammetric methods are applied to quantify geomorphic change, camera calibration is essential to ensure accuracy of the image measurements. Insufficient self-calibration based on survey data can induce systematic errors that can cause DEM deformations. The typically low geometric stability of consumer grade sensors necessitates in-situ calibration, as the reliability of a lab based calibration can be affected by transport. In this research a robust on-site workflow is proposed that allows the time-efficient and repeatable calibration of thermal and optical sensors at the same time. A stone building was utilised as calibration object with TLS scans for reference. The approach was applied to calculate eight separate camera calibrations using two sensors (DJI Phantom 4 Pro and Workswell WIRIS pro), two software solutions (Vision Measurement System (VMS) and Agisoft Metashape) and two different subsets of images per sensor. The presented results demonstrate that the approach is suitable to determine camera parameters for pre-calibrating photogrammetric surveys.

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Maurits, L., M. de Heer, T. Honkola, M. Dunn, and O. Vesakoski. "Best practices in justifying calibrations for dating language families." Journal of Language Evolution 5, no. 1 (December 28, 2019): 17–38. http://dx.doi.org/10.1093/jole/lzz009.

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Abstract The use of computational methods to assign absolute datings to language divergence is receiving renewed interest, as modern approaches based on Bayesian statistics offer alternatives to the discredited techniques of glottochronology. The datings provided by these new analyses depend crucially on the use of calibration, but the methodological issues surrounding calibration have received comparatively little attention. Especially, underappreciated is the extent to which traditional historical linguistic scholarship can contribute to the calibration process via loanword analysis. Aiming at a wide audience, we provide a detailed discussion of calibration theory and practice, evaluate previously used calibrations, recommend best practices for justifying calibrations, and provide a concrete example of these practices via a detailed derivation of calibrations for the Uralic language family. This article aims to inspire a higher quality of scholarship surrounding all statistical approaches to language dating, and especially closer engagement between practitioners of statistical methods and traditional historical linguists, with the former thinking more carefully about the arguments underlying their calibrations and the latter more clearly identifying results of their work which are relevant to calibration, or even suggesting calibrations directly.

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Hollerbach, John M., and Charles W. Wampler. "The Calibration Index and Taxonomy for Robot Kinematic Calibration Methods." International Journal of Robotics Research 15, no. 6 (December 1996): 573–91. http://dx.doi.org/10.1177/027836499601500604.

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Sanders, Kate L., and Michael S. Y. Lee. "Evaluating molecular clock calibrations using Bayesian analyses with soft and hard bounds." Biology Letters 3, no. 3 (March 15, 2007): 275–79. http://dx.doi.org/10.1098/rsbl.2007.0063.

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A limiting factor in many molecular dating studies is shortage of reliable calibrations. Current methods for choosing calibrations (e.g. cross-validation) treat them as either correct or incorrect, whereas calibrations probably lie on a continuum from highly accurate to very poor. Bayesian relaxed clock analysis permits inclusion of numerous candidate calibrations as priors: provided most calibrations are reliable, the model appropriate and the data informative, the accuracy of each calibration prior can be evaluated. If a calibration is accurate, then the analysis will support the prior so that the posterior estimate reflects the prior; if a calibration is poor, the posterior will be forced away from the prior. We use this approach to test two fossil dates recently proposed as standard calibrations within vertebrates. The proposed bird–crocodile calibration (approx. 247 Myr ago) appears to be accurate, but the proposed bird–lizard calibration (approx. 255 Myr ago) is substantially too recent.

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Yuan, Yuan, and Yong Hui Ge. "More Efficient Methods among Commonly Used Robust Estimation Methods for Similarity Transformation." Advanced Materials Research 712-715 (June 2013): 2497–500. http://dx.doi.org/10.4028/www.scientific.net/amr.712-715.2497.

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mage calibration is a necessary step in image processing. Similarity transformation is a widely used image calibration method. Robust estimation methods are often used to eliminate or weaken the influences of gross errors on image calibration. However, different robust estimation methods have different capabilities in eliminating or weakening gross errors. The current paper employed simulation experiments using different coincident points and the number of gross errors included in the observations to compare the robustness of 13 commonly used robust estimation methods. Results indicated that L1 and GermanMcClure methods are relatively more efficient than other robust estimation methods for image calibration based on similarity transformation.

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Kim, Kyung Yong. "A Comparison of the Separate and Concurrent Calibration Methods for the Full-Information Bifactor model." Applied Psychological Measurement 43, no. 7 (November 30, 2018): 512–26. http://dx.doi.org/10.1177/0146621618813095.

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When calibrating items using multidimensional item response theory (MIRT) models, item response theory (IRT) calibration programs typically set the probability density of latent variables to a multivariate standard normal distribution to handle three types of indeterminacies: (a) the location of the origin, (b) the unit of measurement along each coordinate axis, and (c) the orientation of the coordinate axes. However, by doing so, item parameter estimates obtained from two independent calibration runs on nonequivalent groups are on two different coordinate systems. To handle this issue and place all the item parameter estimates on a common coordinate system, a process called linking is necessary. Although various linking methods have been introduced and studied for the full MIRT model, little research has been conducted on linking methods for the bifactor model. Thus, the purpose of this study was to provide detailed descriptions of two separate calibration methods and the concurrent calibration method for the bifactor model and to compare the three linking methods through simulation. In general, the concurrent calibration method provided more accurate linking results than the two separate calibration methods, demonstrating better recovery of the item parameters, item characteristic surfaces, and expected score distribution.

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Piedehierro, A. A., M. L. Cancillo, J. M. Vilaplana, and A. Serrano. "Long-Term Global Irradiance Calibration of Multifilter UV Radiometers." Journal of Atmospheric and Oceanic Technology 36, no. 12 (December 2019): 2415–27. http://dx.doi.org/10.1175/jtech-d-18-0132.1.

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AbstractMultifilter instruments such as the Norwegian Institute for Air Research (NILU)-UV Irradiance Meter (NILU-UV) are suitable for long-term monitoring of UV radiation, as long as their irradiance scale is maintained. The sensitivity of these instruments varies with time; thus, periodic standard absolute calibrations are required. However, standard calibrations may be insufficient to characterize the short-term variations of channels sensitivity. Therefore, results from standard calibrations have to be combined with the information derived from frequent relative calibrations, leading to a stable irradiance scale. This paper focuses on the long-term application of three calibration methods, hereinafter referred to as CC, CC2, and CC2(ϕ), as applied to the NILU-UV 119 multifilter radiometer. Here a generalization is proposed, consisting of using empirical functions in order to guarantee the accurate calibration of multifilter instruments over long time periods. These function-based methods need to be updated regularly to account for changes on instrument sensitivity. The changes in sensitivity of the NILU-UV 119 were found to be channel dependent. The detected drifts range from 23% to 42% for a 4-yr period of study. Time series of calibrated irradiance are obtained by applying the proposed methods. Results suggest that calibration methods using empirical functions perform better than classic calibration approaches that use constant calibration factors. When methods CC2 and CC2(ϕ) are applied, calibrated irradiances agree with the measurements of reference within ±5% for channel 305 and within ±3% for channels 312, 320, and 340.

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Garbacz, Tomasz, and Ľudmila Dulebova. "Calibration Process and Constructions of Extrusion Calibrators." Key Engineering Materials 635 (December 2014): 135–38. http://dx.doi.org/10.4028/www.scientific.net/kem.635.135.

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In the cellular extrusion process, the extrusion head gives the extrudate the desired cross-section shape and dimensions, taking into account the Barus effect and the shrinkage effect. However, if strict requirements are imposed with regard to cross-section shape and dimensions, it is necessary to fix the shape and dimensions by calibrating the extrudate obtained. The aim of this study is to present methods and constructional solutions of calibration tooling (calibrators) and to present the new calibrator that constitutes a significant element of the adapted and modernized technological extrusion line.

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Fontana, G., S. Ruggeri, G. Legnani, and I. Fassi. "Unconventional calibration strategies for micromanipulation work-cells." Robotica 36, no. 12 (August 20, 2018): 1897–919. http://dx.doi.org/10.1017/s0263574718000796.

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SUMMARYThis paper presents and compares a set of calibration strategies useful to calibrate vision-based robotised work-cells for micromanipulation and microassembly. To grasp and release microparts precisely, robot calibration, camera calibration and robot-camera registration are needed. Conventional calibration methods are very onerous at the microscale, therefore, two alternative unconventional procedures, called virtual grid calibration and hybrid calibration, are developed for work-cells with high-performance robots, minimising necessary instrumentation. Moreover, an effective calibration of the robot end-effector is designed to compensate for misalignment and orientation errors with respect to the vertical rotational axis. This paper describes the calibration methods and their implementation, the results and the improvements achieved. A detailed comparison between the hybrid and the virtual grid calibrations is provided, demonstrating the higher performance of the latter strategy.

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Romanczyk, Paul. "Validation methods for geometric camera calibration." Electronic Imaging 2020, no. 16 (January 26, 2020): 150–1. http://dx.doi.org/10.2352/issn.2470-1173.2020.16.avm-149.

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Camera-based advanced driver-assistance systems (ADAS) require the mapping from image coordinates into world coordinates to be known. The process of computing that mapping is geometric calibration. This paper provides a series of tests that may be used to assess the goodness of the geometric calibration and compare model forms: 1. Image Coordinate System Test: Validation that different teams are using the same image coordinates. 2. Reprojection Test: Validation of a camera’s calibration by forward projecting targets through the model onto the image plane. 3. Projection Test: Validation of a camera’s calibration by inverse projecting points through the model out into the world. 4. Triangulation Test: Validation of a multi-camera system’s ability to locate a point in 3D. The potential configurations for these tests are driven by automotive use cases. These tests enable comparison and tuning of different calibration models for an as-built camera.

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Beavan, Alan J. S., Philip C. J. Donoghue, Mark A. Beaumont, and Davide Pisani. "Performance of A Priori and A Posteriori Calibration Strategies in Divergence Time Estimation." Genome Biology and Evolution 12, no. 7 (May 22, 2020): 1087–98. http://dx.doi.org/10.1093/gbe/evaa105.

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Abstract Relaxed molecular clock methods allow the use of genomic data to estimate divergence times across the tree of life. This is most commonly achieved in Bayesian analyses where the molecular clock is calibrated a priori through the integration of fossil information. Alternatively, fossil calibrations can be used a posteriori, to transform previously estimated relative divergence times that were inferred without considering fossil information, into absolute divergence times. However, as branch length is the product of the rate of evolution and the duration in time of the considered branch, the extent to which a posteriori calibrated, relative divergence time methods can disambiguate time and rate, is unclear. Here, we use forward evolutionary simulations and compare a priori and a posteriori calibration strategies using different molecular clock methods and models. Specifically, we compare three Bayesian methods, the strict clock, uncorrelated clock and autocorrelated clock, and the non-Bayesian algorithm implemented in RelTime. We simulate phylogenies with multiple, independent substitution rate changes and show that correct timescales cannot be inferred without the use of calibrations. Under our simulation conditions, a posteriori calibration strategies almost invariably inferred incorrect rate changes and divergence times. The a priori integration of fossil calibrations is fundamental in these cases to improve the accuracy of the estimated divergence times. Relative divergence times and absolute timescales derived by calibrating relative timescales to geological time a posteriori appear to be less reliable than a priori calibrated, timescales.

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Navarro-Villoslada, F., L. V. Pérez-Arribas, M. E. Léon-González, and L. M. Polo-Díez. "Selection of calibration mixtures and wavelengths for different multivariate calibration methods." Analytica Chimica Acta 313, no. 1-2 (September 1995): 93–101. http://dx.doi.org/10.1016/0003-2670(95)00226-p.

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Savelkaev, Sergei V. "UNIVERSAL COAXIAL-STRIPLINE AND PROBE TEST FIXTURES AND THEIR CALIBRATION METHODS." Vestnik SSUGT (Siberian State University of Geosystems and Technologies) 25, no. 4 (2020): 229–37. http://dx.doi.org/10.33764/2411-1759-2020-25-4-229-237.

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The design and calibration method for a coaxial-stripline test fixture that provides connection of microwave circuit analyzer of both coaxial measures and microstrip calibrators, as well as the active components under study, such as transistors, are considered. The test fixture provides high repeatability of connecting coaxial measures, microstrip calibrators, and active components being studied and has a small standing-wave ratio and loss. The test fixture is calibrated with using a minimal set of easily calculated microstrip calibrators with low losses, which, taking into account the high repeatability of their connection, reduces the complexity of its calibration and increases the accuracy of transmitting measurement results from the coaxial line to the microstrip line. The possibility of transmitting measurement results from the coaxial line to the microstrip line extends the scope of the State System for Ensuring the Uniformity of Measurements to the microstrip line. The design of the probe test fixture and a method of its calibration by a specialized microstrip calibrator are also given.

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Jung, Yoon, and Sang-Eun Park. "Comparative Analysis of Polarimetric SAR Calibration Methods." Remote Sensing 10, no. 12 (December 18, 2018): 2060. http://dx.doi.org/10.3390/rs10122060.

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In the diverse applications of polarimetric Synthetic Aperture Radar (SAR) systems, it is a crucial to conduct polarimetric calibration, which aims to remove the radar system distortion effects prior to utilizing polarimetric SAR observations. The objective of this study is to evaluate the performance of different polarimetric calibration methods. Two widely used methods, the Van Zyl and Quegan methods, and one recently proposed method, such as the Villa method, have been selected among various calibration methods in literature. The selected methods have basic differences in their assumptions that are applied to the polarimetric system model. In order to evaluate the calibration performances under different system parameters and ground characteristics, comparative analysis of the calibration results were conducted on synthetic polarimetric SAR data and ALOS PALSAR quad-pol mode data. Based on the experimental results, the advantages and limitations of different methods were clarified, and a simple hybrid calibration method is presented to further improve the polarimetric calibration performance.

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Ono, Kanji. "Calibration Methods of Acoustic Emission Sensors." Materials 9, no. 7 (June 24, 2016): 508. http://dx.doi.org/10.3390/ma9070508.

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Li, Wei Da, Juan Li, and Li Ning Sun. "Calibration Methods of Planar Parallel Robot." Key Engineering Materials 464 (January 2011): 340–43. http://dx.doi.org/10.4028/www.scientific.net/kem.464.340.

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Kinematic calibration is an effective method of improving robotic absolute position accuracy by means of measurement, identification and compensation etc. This paper investigates the technology of kinematic calibration and error compensation for the 2-DOF planar parallel robot. A multi-step calibration method is presented based on error itterative method and nonlinear optimum method. Experimental results indicate that the proposed method can effectively compensate position error of the robot in Oxy plane, and the absolute position error of the calibrated robot is less than 6μm.

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Nair, Murali T. K., and Mei-Chang Cheng. "HDR source calibration methods and discrepancies." International Journal of Radiation Oncology*Biology*Physics 38, no. 1 (April 1997): 207–11. http://dx.doi.org/10.1016/s0360-3016(97)00255-1.

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Stenken, Julie A. "Methods and issues in microdialysis calibration." Analytica Chimica Acta 379, no. 3 (January 1999): 337–58. http://dx.doi.org/10.1016/s0003-2670(98)00598-4.

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Kulikovskiy, Vladimir. "Calibration methods and tools for KM3NeT." EPJ Web of Conferences 116 (2016): 06003. http://dx.doi.org/10.1051/epjconf/201611606003.

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Liao, Hsien-Chou, and Hong-Jhih Wu. "Automatic Camera Calibration and Rectification Methods." Measurement and Control 43, no. 8 (October 2010): 251–54. http://dx.doi.org/10.1177/002029401004300806.

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Panchuk, Vitaly, Dmitry Kirsanov, Ekaterina Oleneva, Valentin Semenov, and Andrey Legin. "Calibration transfer between different analytical methods." Talanta 170 (August 2017): 457–63. http://dx.doi.org/10.1016/j.talanta.2017.04.039.

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