Hyperion on-orbit validation of spectral calibration using atmospheric lines and an on-board system

Barry, P.S.; Shepanski, John; Segal, C.

doi:10.1117/12.453344

Cited by 23 publications

(13 citation statements)

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“…When relying solely on image data, the reference spectrum is usually given by the modeled at-sensor radiance [5], transmittance, or irradiance [4] signals containing atmospheric absorption features. When available, onboard spectral calibration sources may provide a valid alternative to image data as well as a useful complement covering spectral regions devoid of atmospheric features; reference signals are then usually diffuser plates' absorption lines or dedicated filter transmittances [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Performance assessment of onboard and scene-based methods for Airborne Prism Experiment spectral characterization

et al. 2011

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Accurate spectral calibration of airborne and spaceborne imaging spectrometers is essential for proper preprocessing and scientific exploitation of high spectral resolution measurements of the land and atmosphere. A systematic performance assessment of onboard and scene-based methods for in-flight monitoring of instrument spectral calibration is presented for the first time in this paper. Onboard and ground imaging data were collected at several flight altitudes using the Airborne Prism Experiment (APEX) imaging spectrometer. APEX is equipped with an in-flight characterization (IFC) facility allowing the evaluation of radiometric, spectral, and geometric system properties, both in-flight and on-ground for the full field of view. Atmospheric and onboard filter spectral features present in at-sensor radiances are compared with the same features in reference transmittances convolved to varying instrument spectral configurations. A spectrum-matching algorithm, taking advantage of the high sensitivity of measurements around sharp spectral features toward spectrometer spectral performance, is used to retrieve channel center wavelength and bandwidth parameters. Results showed good agreement between spectral parameters estimated using onboard IFC and ground imaging data. The average difference be-tween estimates obtained using the O2 and H2O features and those obtained using the corresponding filter features amounted to about 0:3 nm (0.05 of a spectral pixel). A deviation from the nominal labora-tory instrument spectral calibration and an altitude-dependent performance was additionally identified. The relatively good agreement between estimates obtained by the two approaches in similar spectral windows suggests they can be used in a complementary fashion: while the method relying on atmospheric features can be applied without the need for dedicated calibration acquisitions, the IFC allows assessment at user-selectable wavelength positions by custom filters as well as for the system on-ground. Accurate spectral calibration of airborne and spaceborne imaging spectrometers is essential for proper preprocessing and scientific exploitation of high spectral resolution measurements of the land and atmosphere. A systematic performance assessment of onboard and scene-based methods for in-flight monitoring of instrument spectral calibration is presented for the first time in this paper. Onboard and ground imaging data were collected at several flight altitudes using the Airborne Prism Experiment (APEX) imaging spectrometer. APEX is equipped with an in-flight characterization (IFC) facility allowing the evaluation of radiometric, spectral, and geometric system properties, both in-flight and on-ground for the full field of view. Atmospheric and onboard filter spectral features present in at-sensor radiances are compared with the same features in reference transmittances convolved to varying instrument spectral configurations. A spectrum-matching algorithm, taking advantage of the high sensitivity of measurements around sh...

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Section: Introductionmentioning

confidence: 99%

Performance assessment of onboard and scene-based methods for Airborne Prism Experiment spectral characterization

et al. 2011

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“…Different merit functions can be used to assess the goodness of each iterative match, such as position of the feature's peak, position of the feature's center of gravity (COG), standard deviation, or Pearson's correlation coefficient. Pearson's correlation coefficient has been chosen for this study as the merit function to be maximized; reasons for this choice lie in the results obtained by means of a sensitivity study [27] and on a review of literature [16,17,[29][30][31][32]. In the sensitivity analysis, simulated datasets were used to compare different merit functions, whereby the correlation analysis gave the best results with uncertainties in the order of 1%-3% of a pixel.…”

Section: A Methodsmentioning

confidence: 99%

“…The Hyperion system looks at the Sun rising through the limb of the Earth. In this way, light passes through the atmosphere before reflecting off the solar calibration panel into the instrument aperture, providing a spectrum rich in solar lines, atmospheric lines, and absorption lines from the paint that coats the panel [17].…”

Section: Introductionmentioning

confidence: 99%

In-flight spectral performance monitoring of the Airborne Prism Experiment

2010

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Spectral performance of an airborne dispersive pushbroom imaging spectrometer cannot be assumed to be stable over a whole flight season given the environmental stresses present during flight. Spectral performance monitoring during flight is commonly accomplished by looking at selected absorption features present in the Sun, atmosphere, or ground, and their stability. The assessment of instrument performance in two different environments, e.g., laboratory and airborne, using precisely the same calibration reference, has not been possible so far. The Airborne Prism Experiment (APEX), an airborne dispersive pushbroom imaging spectrometer, uses an onboard in-flight characterization (IFC) facility, which makes it possible to monitor the sensor's performance in terms of spectral, radiometric, and geometric stability in flight and in the laboratory. We discuss in detail a new method for the monitoring of spectral instrument performance. The method relies on the monitoring of spectral shifts by comparing instrument-induced movements of absorption features on ground and in flight. Absorption lines originate from spectral filters, which intercept the full field of view (FOV) illuminated using an internal light source. A feature-fitting algorithm is used for the shift estimation based on Pearson's correlation coefficient. Environmental parameter monitoring, coregistered on board with the image and calibration data, revealed that differential pressure and temperature in the baffle compartment are the main driving parameters explaining the trend in spectral performance deviations in the time and the space (across-track) domains, respectively. The results presented in this paper show that the system in its current setup needs further improvements to reach a stable performance. Findings provided useful guidelines for the instrument revision currently under way. The main aim of the revision is the stabilization of the instrument for a range of temperature and pressure conditions to be encountered during operation.

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“…The demonstrated spaceborne hyperspectral sensor to date was HYPERION 1) from NASA (National Aeronautics and Space Administration) and CHRIS 2) from ESA (European Space Agency). These sensors were calibrated by the Atmospheric Limb Corecction 3) . On the other hand, the calibration process which used O 2 and H 2 O absorptions are not enough accuracy that is required for hyperspectral sensor.…”

Section: Introductionmentioning

confidence: 99%

Breadboard Model of On-orbit Calibration Equipment for Small Hyperspectral Sensor

Aoyanagi

Satori

Takeuchi³

2010

AEROSPACE TECHNOLOGY JAPAN

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This paper examined the effect of atmospheric correction on that hyperspectral sensors have wavelength error. Also we examined the effects of classification result on erroneous atmospheric correction. Additionally, this paper proposes new spectral calibration device named OCE (On-orbit Calibration Equipment) which consists of the visible and near infrared LEDs. The calibration accuracy by OCE compared with spectral lines of mercury and xenon has been evaluated. The OCE-BBM to central pixel of spatial direction can be calibrated with sufficient accuracy.

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Hyperion on-orbit validation of spectral calibration using atmospheric lines and an on-board system

Cited by 23 publications

References 1 publication

Performance assessment of onboard and scene-based methods for Airborne Prism Experiment spectral characterization

Performance assessment of onboard and scene-based methods for Airborne Prism Experiment spectral characterization

In-flight spectral performance monitoring of the Airborne Prism Experiment

Breadboard Model of On-orbit Calibration Equipment for Small Hyperspectral Sensor

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