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过滤筛选
- 2015
- Calibration process of OSL detectors
- Iodine-131
- OSL-BeO
- Dosimetry of staff and patients
- Optically Stimulated Luminescence (OSL)
- Akdeniz University
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Improved auto-extrinsic calibration between stereo vision camera and laser range finder
摘要： This study identifies a way to accurately estimate extrinsic calibration parameters between stereo vision camera and 2D laser range finder (LRF) based on 3D reconstruction of monochromatic calibration board and geometric co-planarity constraints between the views from these two sensors. It supports automatic extraction of plane-line correspondences between camera and LRF using monochromatic board, which is further improved by selecting optimal threshold values for laser scan dissection to extract line features from LRF data. Calibration parameters are then obtained by solving co-planarity constraints between the estimated plane and line. Furthermore, the obtained parameters are refined by minimising reprojection error and error from the co-planarity constraints. Moreover, calibration accuracy is achieved because of extraction of reliable plane-line correspondence using monochromatic board which reduces the impact of range-reflectivity-bias observed in LRF data on checkerboard. As the proposed method supports to automatically extract feature correspondences, it provides a major reduction in time required from an operator in comparison to manual methods. The performance is validated by extensive experimentation and simulation, and estimated parameters from the proposed method demonstrate better accuracy than conventional methods.
关键词： plane-line correspondences,laser-camera calibration,Range-reflectivity-bias,automatic feature extraction
更新于2025-09-23 15:19:57
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - A Quantum Hall Effect Kelvin Bridge for Resistance Calibration
摘要： We describe a resistance ratio bridge suitable for calibrating a four-terminal resistor of value close to the quantum Hall resistance. The bridge includes three quantum Hall elements, wired with multiple connections. The unique properties of the quantum Hall effect provide a Kelvin-like combining network and the rejection of wiring stray resistances. The bridge has a simple schematic and does not include any adjustable element: its reading is the deviation from equilibrium, measured as a small voltage ratio. Circuit network analysis predicts that a basic implementation of the bridge can reach a calibration accuracy in the 10?8 range.
关键词： calibration,Quantum Hall effect,resistance standards,resistance bridge
更新于2025-09-23 15:19:57
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A Full-Parameter Self-Calibration Method Based on Inertial Frame Filtering for Triaxis RINS under Swaying Base
摘要： The navigation performance of the rotational inertial navigation system (RINS) could be greatly improved by self-calibration traditional instrument-level calibration depends on high-precision turntable. System-level calibration takes zero velocity as reference to estimate error parameters. However, zero velocity is invalid in the situation of swaying base and the calibration accuracy will be decreased with the traditional method. Aiming at the swaying base environment, the filtering method for tri-axis RINS in inertial frame is proposed in this paper. Taking the velocity errors in the inertial frame as the reference, full-parameter calibration on swaying base can be achieved. Simulation verifies the feasibility of the proposed method. Experimental results demonstrate the stability of the proposed method is better than the traditional calibration method and it satisfies the application requirements. Thus, the proposed method has great application values under swaying base.
关键词： Swaying base,Filtering,Self-calibration,Inertial frame,RINS
更新于2025-09-23 15:19:57
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Atmospheric particulate matter characterization by Fourier transform infrared spectroscopy: a review of statistical calibration strategies for carbonaceous aerosol quantification in US measurement networks
摘要： Atmospheric particulate matter (PM) is a complex mixture of many different substances and requires a suite of instruments for chemical characterization. Fourier transform infrared (FT-IR) spectroscopy is a technique that can provide quantification of multiple species provided that accurate calibration models can be constructed to interpret the acquired spectra. In this capacity, FT-IR spectroscopy has enjoyed a long history in monitoring gas-phase constituents in the atmosphere and in stack emissions. However, application to PM poses a different set of challenges as the condensed-phase spectrum has broad, overlapping absorption peaks and contributions of scattering to the mid-infrared spectrum. Past approaches have used laboratory standards to build calibration models for prediction of inorganic substances or organic functional groups and predict their concentration in atmospheric PM mixtures by extrapolation. In this work, we review recent studies pursuing an alternate strategy, which is to build statistical calibration models for mid-IR spectra of PM using collocated ambient measurements. Focusing on calibrations with organic carbon (OC) and elemental carbon (EC) reported from thermal–optical reflectance (TOR), this synthesis serves to consolidate our knowledge for extending FT-IR spectroscopy to provide TOR-equivalent OC and EC measurements to new PM samples when TOR measurements are not available. We summarize methods for model specification, calibration sample selection, and model evaluation for these substances at several sites in two US national monitoring networks: seven sites in the Interagency Monitoring of Protected Visual Environments (IMPROVE) network for the year 2011 and 10 sites in the Chemical Speciation Network (CSN) for the year 2013. We then describe application of the model in an operational context for the IMPROVE network for samples collected in 2013 at six of the same sites as in 2011 and 11 additional sites. In addition to extending the evaluation to samples from a different year and different sites, we describe strategies for error anticipation due to precision and biases from the calibration model to assess model applicability for new spectra a priori. We conclude with a discussion regarding past work and future strategies for recalibration. In addition to targeting numerical accuracy, we encourage model interpretation to facilitate understanding of the underlying structural composition related to operationally defined quantities of TOR OC and EC from the vibrational modes in mid-IR deemed most informative for calibration. The paper is structured such that the life cycle of a statistical calibration model for FT-IR spectroscopy can be envisioned for any substance with IR-active vibrational modes, and more generally for instruments requiring ambient calibrations.
关键词： thermal-optical reflectance,statistical calibration,elemental carbon,IMPROVE network,Chemical Speciation Network,FT-IR spectroscopy,organic carbon,atmospheric particulate matter
更新于2025-09-19 17:15:36
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Lateral scale calibration for focus variation microscopy
摘要： Areal surface texture measuring instruments can be calibrated by determining a set of metrological characteristics currently in the final stages of standardisation. In this paper, amplification, linearity and perpendicularity characteristics have been determined to calibrate the lateral performance of a focus variation microscope. The paper presents a novel and low-cost material measure and procedures that are used to determine the characteristics. The material measure is made of stainless steel with a cross-grating grid of hemispherical grooves. The design, manufacture and calibration of the material measure are discussed. The 20 × 20 mm grid is measured with and without image stitching. The results show that the proposed material measure and procedures can be used to determine the error of the amplification, linearity and perpendicularity characteristics. In addition, the lateral stage error can be significantly reduced by measurement with image stitching.
关键词： focus variation microscopy,amplification coefficient,lateral calibration,metrological characteristics,linearity deviation,perpendicularity deviation
更新于2025-09-19 17:15:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Sentinel-2 Level-L Radiometry Validation Using Vicarious Methods from Dimitri Database
摘要： Sentinel-2 is an Earth Observation optical mission developed and operated by the European Space Agency (ESA) in the frame of the Copernicus program of the European Commission. The mission consists on a MultiSpectral Instruments (MSI) on board a constellation of two satellites flying on the same orbit but phased at 180°: Sentinel-2A launched in June 2015 and Sentinel-2B launched in March 2017. It covers the Earth’s land surfaces and inland and coastal waters every five days at the equator under the same viewing conditions with high spatial resolution and wide field of view. Accurate radiometric calibration is key to the success of the mission; therefore, in-orbit calibration and validation activities are conducted within the Sentinel-2 Mission Performance Centre (MPC), including a consortium of Expert Support Laboratories (ESL). The Database of Imaging Multispectral Instrument and Tool for Radiometric Intercomparison (DIMITRI) is used to perform the vicarious validation of Level-1 products delivered to users. The aims of this validation are 1) to assess the quality of the data product at Level-1, 2) to monitor the evolution of the radiometry of both instruments and 3) to ensure that the products meet the mission requirement accuracy. Three vicarious methods are used, such as Rayleigh scattering, Desert Pseudo-Invariant Calibration Sites (PICS) and Sensor-to-Sensor inter-calibration methods. Although the results indicate good stability and performance of both sensors MSI-A/B, a slight discrepancy between them of ~1% over desert sites could be observed. Slight decrease of band B8A (865 nm) signal over Algeria-3 site has been detected since April 2017. This effect seems to be related to the impact of human and industry activities near the area. Radiometric performances and image quality of Sentinel-2 MSI-A/B level-1C products appear stable and meet the mission requirements.
关键词： Multispectral Instrument,validation,vicarious calibration methods,Remote sensing,Radiometry
更新于2025-09-19 17:15:36
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On-Orbit Camera Misalignment Estimation Framework and Its Application to Earth Observation Satellite
摘要： Despite the efforts for precise alignment of imaging sensors and attitude sensors before launch, the accuracy of pre-launch alignment is limited. The misalignment between attitude frame and camera frame is especially important as it is related to the localization error of the spacecraft, which is one of the essential factors of satellite image quality. In this paper, a framework for camera misalignment estimation is presented with its application to a high-resolution earth-observation satellite—Deimos-2. The framework intends to provide a solution for estimation and correction of the camera misalignment of a spacecraft, covering image acquisition planning to mathematical solution of camera misalignment. Considerations for effective image acquisition planning to obtain reliable results are discussed, followed by a detailed description on a practical method for extracting many GCPs automatically using reference ortho-photos. Patterns of localization errors that commonly occur due to the camera misalignment are also investigated. A mathematical model for camera misalignment estimation is described comprehensively. The results of simulation experiments showing the validity and accuracy of the misalignment estimation model are provided. The proposed framework was applied to Deimos-2. The real-world data and results from Deimos-2 are presented.
关键词： earth-observation satellite,on-orbit calibration,camera misalignment,boresight alignment
更新于2025-09-19 17:15:36
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Extension of the range of profile surface roughness measurements using metrological atomic force microscope
摘要： The calibration service of profile surface roughness by using a metrological atomic force microscope is now available at National Metrology Institute of Japan (NMIJ), AIST. The calibration method is designed by referring to ISO 19606: 2017 (JIS R 1683: 2014). The scope of the ISO 19606: 2017, however, is limited to roughness measurements of surfaces with an arithmetical mean roughness, Ra, in the range of about 1 nm–30 nm. Currently there is strong demand for the measurement of surface roughness of more than 30 nm in the precision machining industry and for the measurement of surface roughness of sub-nanometer order in the semiconductor industry. In order to meet such demand, it is necessary to extend the range of surface roughness measurements in the NMIJ's calibration service. In this study, authors performed surface roughness measurements using a metrological AFM and evaluated their uncertainties. As a result of a series of measurements and evaluation of their uncertainties, it has been found that the calibration range can be extended to surfaces with an arithmetical mean roughness, Ra, in the range of about 0.2 nm–100 nm. The measurement results and the future challenges are reported in this paper.
关键词： Probe-tip diameter evaluation,Calibration,Metrological AFM,Surface roughness
更新于2025-09-19 17:15:36
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[IEEE 2018 International Conference on Frontiers of Information Technology (FIT) - Islamabad, Pakistan (2018.12.17-2018.12.19)] 2018 International Conference on Frontiers of Information Technology (FIT) - Mesh of SSVEP-Based BCI and Eye-Tracker for Use of Higher Frequency Stimuli and Lower Number of EEG Channels
摘要： Steady-State Visually Evoked Potential (SSVEP) is widely used in brain-computer interface (BCI) systems. However, the use of flickering stimuli at low frequencies causes visual fatigue for users. The visual fatigue increases when multiple stimuli are used, flickering at different frequencies. To overcome this problem, this paper present a solution by using single high frequency (30 Hz) stimulus interface with 30 targets. In the proposed system, the initial recognition of the target was achieved through the eye gaze position using an eye-tracker, and the selection/classification of command was provided by EEG. As only a single stimulating frequency was used (i.e. 30 Hz), thus, only two EEG electrodes (at positions PZ and OZ ) were used along with g.USBamp amplifier. This reduced the setup-time for the preparation of the users. A new calibration technique for the eye tracker was designed and developed, which resulted in better eye gaze tracking. The results showed that higher classification accuracies can be achieved by using the mesh of SSVEP-based BCI system and eye-tracker as compared to the SSVEP-based BCI system.
关键词： The EyeTribe calibration,High frequency stimuli,Brain-Computer Interface(BCI),Steady-State Visual Evoked Potential (SSVEP)
更新于2025-09-19 17:15:36
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[IEEE 2018 15th International Conference on Control, Automation, Robotics and Vision (ICARCV) - Singapore, Singapore (2018.11.18-2018.11.21)] 2018 15th International Conference on Control, Automation, Robotics and Vision (ICARCV) - Virtual Commissioning of Machine Vision Applications in Aero Engine Manufacturing
摘要： New aero engine design puts new demands on the manufacturing methods with increased automation level. Therefore, the use of vision sensors for control and guiding of industrial robots is being increasingly used. In such system, it is need to customise the machine vision system with real components in the real environment which is normally done close to the start-up of the production. This paper addresses a new concept for designing, programming, analysing, testing and verifying a machine vision application early in the design phase, called Virtual Machine Vision. It is based on a robot simulation software where the real machine vision application is simulated before the implementation in the production line. To verify the Virtual Machine Vision concept an advanced stereo vision application was used. Using two captured images from the robot simulated environment, camera calibration, image analysis and stereo vision algorithms are applied to determine a desired welding joint. The information of the weld joint, i.e. robot position and orientation for the weld path, are sent from the machine vision system to the robot control system in the simulation environment and the weld path is updated. The validation of the Virtual Machine Vision concept using the stereo vision application is promising for industrial use, and it is emphasised that the same programs are used in the virtual and real word.
关键词： simulation,robotics,welding,machine vision,image processing,Virtual Machine Vision,stereo vision,camera calibration
更新于2025-09-19 17:15:36