Paul Budkewitsch

Vicarious calibration of airborne hyperspectral sensors in operational environments

Abstract A reflectance-based vicarious calibration (RBVC) method has been used to correct the radiometric coefficients for hyperspectral data obtained with the Probe 1 sensor over the Raglan region of northern Quebec, and to perform a radiance renormalisation for compact airborne spectrographic imager (casi) data obtained over Goose Bay, Labrador. It relies on the simultaneous acquisition of ground-based reflectance spectra for at least one calibration site within the hyperspectral flight line. The RBVC method yields a new set of radiometric coefficients that convert the hyperspectral data from digital numbers (DNs) to radiances, and that are applicable to flight lines taken under different conditions. For both the Raglan and the Goose Bay projects, the calibration site was a gravel airstrip, and ground-based reflectance measurements were made with a GER3700 field spectrometer using a Spectralon panel for reference. This represents a novel use of the RBVC method for validation and correction of the sensors radiometric calibration at the time of data acquisition, applied in an operational setting that lacks a large, bright and homogeneous calibration target and well-characterized atmospheric conditions. Analysis of the errors involved in correcting the radiometric coefficients yielded a total relative error (averaged over wavelength) of 3.9–5.6% on the final reflectance spectra.

Initial examination of radar imagery of optical radiometric calibration sites

In-flight absolute radiometric calibration is critical for multi-temporal and multi-sensor data comparisons. In the case of vicarious calibration of optical sensors based on ground-level measurements, the test site must be well characterized in spatial, radiometric, spectral, and temporal domains. Remotely sensed data acquired at other wavelengths can contribute to a baseline understanding of ground targets and provide insight into the usefulness of such targets for in-flight calibration of optical sensors. With these considerations in mind, multi-temporal ERS-1 SAR data have been obtained for White Sands, New Mexico, and Lunar Lake and Railroad Valley playas in Nevada. This paper reports on an initial examination of these SAR image data sets and the significant pattern changes observed in the scenes. It is concluded that surface roughness, soil moisture and run-off are major factors giving rise to the observed scene characteristics.

RADARSAT-2; are its technical capabilities expected to provide potential for remote sensing applications ?

In this paper, we preview and demonstrate how the technical improvements included in RADARSAT-2 will impact the systems potential utility for 32 applications in the fields of agriculture, cartography, disaster management, forestry, geology, hydrology, oceans, and sea and land ice.

Applications potential of planned C-band SAR satellites: leading to RADARSAT-2

To date, satellite SAR data for civilian purposes, have been routinely available from single channel, i.e., single frequency and single polarization, radar systems. In the near future, we expect satellite SAR systems with enhanced capabilities in terms of polarization, frequency, spatial resolution, spatial coverage and temporal resolution. In this paper, we discuss the increase in applications potential resulting from the progress in SAR technology, in particular in C-band systems. The application fields discussed include agriculture, forestry, geology, hydrology, oceans, and sea ice. Most applications are anticipated to benefit from the upcoming availability of cross-polarized C-band data. Likewise the introduction of fully polarimetric C-band satellite SAR systems is expected to improve the overall application potential.

Temporal snow cover variation and terrain characteristics of Peary caribou habitats in the Canadian arctic using optical and InSAR data

Interferometric synthetic aperture radar (InSAR) data from RADARSAT-1 have been examined to assess their potential for mapping terrain and changes in snow cover characteristics, relative to the limiting effects of snow on foraging by endangered Peary caribou (Rangifer tarandus). Radar is one of the few observational tools that can provide information on the changing snow pack during the dark winter months. The goal of this research is to characterize the general ensemble of terrain characteristics that may affect winter foraging patterns of Peary caribou and the inter-annual consistency of snow cover patterns within our specific study area

Geological map update using airborne and RADARSAT simulated SAR data in Sarawak, Malaysia

Abstract Synthetic Aperture Radar data acquired in Sarawak, Malaysia, were interpreted geologically in terms of lithology and structure. The data were merged with existing maps to facilitate interpretation. However, the small scale of the geological map did not provide useful details. Three lithological groups, namely: riverine alluvium, molasse deposits, and flysch deposits were differentiated on the basis of their morphological and textural appearances. Three major faults were also identified, namely: the Bukit Mersing Line, the Tubau Fault, and another newly named Kalo Fault. The Airborne SAR data were processed to simulate RADARSAT standard mode data. The simulated data retained all the information concerning the faults and folds. The reduced resolution did result in decreased, but still present, capabilities to trace the lithological units and beds. Overall, the airborne and simulated RADARSAT images proved to be a very useful tool to visually enhance and understand the geology, both at a local and r...

ASTER - a geological mapping tool for Canada's North. Case Study: The Belcher Islands, Hudson Bay, Nunavut, Canada

Extensive areas of Canadas North lack regional scale, high quality geological maps due to their limited access and high traditional field mapping costs. Remote sensing techniques, such as that of the ASTER sensor are being evaluated as a tool to assist with regional geological mapping, The Belcher Fold Belt, a geologically mapped and accessible area in the Canadian Arctic with significant exposure, low vegetation and topography, was chosen as a site for evaluation of ASTERs geological mapping capabilities.

RADARSAT-1 interferometric potential for monitoring volcanic activity: the Guagna Pichincha Volcano, Ecuador

The Guagua Pichincha volcano close to Quito, Ecuador has been erupting since August 1998. To monitor its behaviour, RADARSAT-1 fine mode data were acquired in March, April, October, and November of 1999. Change detection has been carried out using these images. In this study, the capability, utility and limitations of such SAR imagery for monitoring of volcanic activity is being examined.

Influence of SAR wavelength and polarization on geological interpretation of arid terrains

Polarimetric SAR data in C-, L-, and P-band were analyzed for an arid area in central Nevada. Differentiations in alluvial fans provenance can only be mapped with C-band like-polarized data because the size fragments of the alluvium. The location of the associated drainage channels are however best identified with L-band data. The P-band data does not show as much contrast between the channels and the surrounding alluvium, perhaps because of decreased sensitivity. However, the P-band data are best suited to make lithological inferences in the more vegetated mesas overlooking the study area.