Laboratory panel and radiometer calibration

Deadman, Andrew; Behnert, I.; Fox, Nigel; Griffith, D.

doi:10.1109/igarss.2011.6050079

Cited by 6 publications

(4 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The remaining uncertainties include the following: Variations in illumination (due to solar zenith, nearby objects, and atmospheric scattering), Spectralon panel degradation, reference-to-target measurement timing, and temperature of FR Spectroradiometer instrument. This study did not include a systematic Type A procedure to measure uncertainties, so estimates of percentage declines in performance for each attribute are provided in Table 4 based upon the various measurement uncertainties provided in Hueni, Damm, Kneubuehler, Schläpfer, and Schaepman [19], Möller, Nikolaus, and Höpe [18], Deadman, Behnert, Fox, and Griffith [20] and Malthus and MacLellan [21]. The recommendations made by Hueni, Damm, Kneubuehler, Schläpfer, and Schaepman [19] to reduce uncertainty measures (excluding the age of Spectralon panel) have been indirectly achieved by the reproducibility of the study design.…”

Section: Discussionmentioning

confidence: 99%

“…Reproducibility was achieved via fixed frames and controlled geometries of all moving parts and instruments [19]. In terms of Lambertian scatter uncertainty, Deadman, Behnert, Fox, and Griffith [20] recorded minimal uncertainty of <0.1% reflectance factor for six reference panels from a 500 nm wavelength at 45 • . Their result was conducted under controlled laboratory conditions so our estimate of 3% error for Lambertian scatter is precautionary to cater for external environmental variation.…”

Section: Discussionmentioning

confidence: 99%

“…The reflectance calculation is the ratio of the shadow signature to the optimised reference panel signature, thus minimising atmospheric and illumination effects such as any irradiance obstruction from the operator, wire crate, occulter, instruments, and the sky hemisphere reductions shown in Figure 4. Estimates of measurement uncertainties in the design result from illumination variation, illumination variance caused by nearby objects, geometry of the design, Spectralon panel degradation, and the Lambertian scatter properties of the Spectralon panel [18][19][20][21]. Estimations of these measurement uncertainties by these factors are provided in the Discussion.…”

Section: Fr Spectroradiometermentioning

confidence: 99%

See 2 more Smart Citations

The Depths of Cast Shadow

McCarthy

Kumar

2019

Remote Sensing

View full text Add to dashboard Cite

To improve the accuracy of analysis outputs from remotely sensed images, shadow and illumination effects need to be minimised or removed. Shadow behaviour at different spectral wavelengths needs to be understood to quantify shadow accurately. This study examined whether a normalised spectral signature of shadow is invariant to sun–object–sensor geometry and can be used to quantify shadow depth. A “FieldSpec® Pro FR” Spectroradiometer and a Canon 450D digital SLR camera were used to measure signatures of cast shadow. Our field-based experiment used an occulter to cast shadow onto a ‘Spectralon’ white plate at six incremental zenith angles and evaluated shadow behaviour within and between varying footprints. A white-balanced image of each shadow zenith was taken by the Canon 450D. The FR Spectroradiometer signatures were normalised to unit vector form and compared to longitudinal transect profiles of shadow from normalised camera images using a scattering index (SI). The normalised signatures show that shadow depth is darker and more ‘blue’ at the proximal areas and conversely that image brightness values increases towards distal areas. Since image brightness is a result of sun–object–sensor geometry, we conclude that a normalised spectral signature is invariant to geometry and can be used to quantify shadow depth.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Fr Spectroradiometermentioning

confidence: 99%

See 1 more Smart Citation

The Depths of Cast Shadow

McCarthy

Kumar

2019

Remote Sensing

View full text Add to dashboard Cite

show abstract

“…The primary purpose of this campaign was to share methodologies, evaluate differences in procedures and develop 'best practices' for obtaining surface reflectance. Results from this effort were reported at IGARSS 2011 in Vancouver, Canada [2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Recent surface reflectance measurement campaigns with emphasis on best practices, SI traceability and uncertainty estimation

Helder¹,

Thome²,

Aaron³

et al. 2012

Metrologia

View full text Add to dashboard Cite

A significant problem facing the optical satellite calibration community is limited knowledge of the uncertainties associated with fundamental measurements, such as surface reflectance, used to derive satellite radiometric calibration estimates. In addition, it is difficult to compare the capabilities of calibration teams around the globe, which leads to differences in the estimated calibration of optical satellite sensors. This paper reports on two recent field campaigns that were designed to isolate common uncertainties within and across calibration groups, particularly with respect to ground-based surface reflectance measurements. Initial results from these efforts suggest the uncertainties can be as low as 1.5% to 2.5%. In addition, methods for improving the cross-comparison of calibration teams are suggested that can potentially reduce the differences in the calibration estimates of optical satellite sensors.

show abstract