1,721,139 research outputs found
Airborne hyperspectral image data of Heron Reef, Australia
No full textThis airborne hyperspectral (19 bands) image data of Heron Reef, Great Barrier Reef, Australia is derived from Compact Airborne Spectrographic Imager (CASI) data acquired on 1st and 3rd of July 2002, latitude -23.45, longitude 151.92. Processing and correction to at-surface data was completed by Karen Joyce (Joyce, 2004). Raw imagery consisted several images corresponding to the number of flight paths taken to cover the entire Heron Reef. Spatial resolution is one meter. Radiometric corrections converted the at-sensor digital number values to at surface spectral radiance values using sensor specific calibration coefficients and CSIRO's c-WomBat-c atmospheric correction software. Geometric corrections were done using field collected coordinates of features identified in the image. Projection used was Universal Transverse Mercator Zone 56 South and Datum used was WGS 84. Image data is in TIFF format
Bathymetric map of Heron Reef, Australia, derived from airborne hyperspectral data at 1 m resolution
No full textA simple method for efficient inversion of arbitrary radiative transfer models for image analysis is presented. The method operates by representing the shape of the function that maps model parameters to spectral reflectance by an adaptive look-up tree (ALUT) that evenly distributes the discretization error of tabulated reflectances in spectral space. A post-processing step organizes the data into a binary space partitioning tree that facilitates an efficient inversion search algorithm. In an example shallow water remote sensing application, the method performs faster than an implementation of previously published methodology and has the same accuracy in bathymetric retrievals. The method has no user configuration parameters requiring expert knowledge and minimizes the number of forward model runs required, making it highly suitable for routine operational implementation of image analysis methods. For the research community, straightforward and robust inversion allows research to focus on improving the radiative transfer models themselves without the added complication of devising an inversion strategy. A bathymetric map of Heron Reef, Great Barrier Reef, Australia at 1 m resolution. The map is derived from Compact Airborne Spectrographic Imager (CASI) data acquired on 1st and 3rd of July 2002, latitude -23.45, longitude 151.92. The data was processed using a radiative transfer model inversion technique, fully described in the related article, Hedley et al. 2009. This dataset corresponds to the treatment described as "Detailed Depth ALUT" in that paper and shown in Figure 5c. The data is not tide corrected and consists of stitched flight lines taken at slightly different times, the linear discontinuity seen across the right of the image is probably due to small tidal variation between flight line times. Small gaps in the image are due to gaps in coverage between the flight lines
Australia's Black Summer wildfires
No full textIn this dataset we provide various metrics for the Black Summer wildfires of Australia (September 2019 - mid February 2020), whose area was larger than 100 sq.km. To this end we treated each wildfire as a wildfire event, and extracted various metrics which are either based on the polygon of the extent of the wildfire, or on the approximate ignition point of that wildfire. Our aim was to understand the climatic, vegetation and anthropogenic variables which might explain the wildfires - their spatial and temporal extent, the burn severity etc. The data was collected from a wide range of (mostly) public freely available datasets, full references provided in our publication mentioned below.
This dataset includes the burn date of all Black Summer wildfires of Australia (September 2019 - mid February 2020) based on MODIS and VIIRS, polygons of the largest (> 100 sq.km.) fires (n = 391), and their approximate ignition points. In addition the excel file contains 10 response variables of the fires, and a range of climatic, vegetation and anthropogenic explanatory variables we used to study these fires
Spectral reflectance library of corals and benthic features in the Cook Islands (Aitutaki)
No full textSpectral reflectances of 118 samples were recorded in situ. An Ocean Optics USB2000 spectrometer was deployed in a custom made underwater housing with a 0.5 m fibre-optic probe mounted next to an artificial light source. Spectral readings were collected with the probe(bear fibre) about 5 cm from the target to ensure that the target would fill the field of view of the fibre optic (FOV diameter ~4.4 cm), as well as to reduce the attenuating effect of the intermediate water (Roelfsema et al., 2006). Spectral readings included for one target included: 1 reading of the covered spectral fibre to correct for instrument noise, 1 reading of a spectralon panel mounted on the diver's wrist to measure incident ambient light, and six to eight readings of the target. Spectral reflectance was calculated for each target by first subtracting the instrument noise reading from each other reading. The corrected target readings were then divided by the corrected spectralon reading resulting in spectral reflectance of each target reading. An average target spectral reflectance was calculated by averaging six to eight individual spectral reflectances of the target. If an individual target spectral reflectance was visually considered an outlier, it was not included in the average spectral reflectance calculation. See Roelfsema at al. (2006) for additional info on the methodology of underwater spectra collection
Spectral reflectance library of healthy corals, bleached corals and other benthic features in Fiji
No full textRadiance-reflectance measurements of the coral types and forms, seagrasses, algae and other benthic features were collected in Fiji in 2006. Spectral reflectances of 239 samples were recorded in situ. An Ocean Optics USB2000 spectrometer was deployed in a custom made underwater housing with a 0.5 m fibre-optic probe mounted next to an artificial light source. Spectral readings were collected with the probe(bear fibre) about 5 cm from the target to ensure that the target would fill the field of view of the fibre optic (FOV diameter ~4.4 cm), as well as to reduce the attenuating effect of the intermediate water (Roelfsema et al., 2006). Spectral readings included for one target included: 1 reading of the covered spectral fibre to correct for instrument noise, 1 reading of a spectralon panel mounted on the diver's wrist to measure incident ambient light, and six to eight readings of the target. Spectral reflectance was calculated for each target by first subtracting the instrument noise reading from each other reading. The corrected target readings were then divided by the corrected spectralon reading resulting in spectral reflectance of each target reading. An average target spectral reflectance was calculated by averaging six to eight individual spectral reflectances of the target. If an individual target spectral reflectance was visually considered an outlier, it was not included in the average spectral reflectance calculation. See Roelfsema at al. (2006) for additional info on the methodology of underwater spectra collection
Spectral reflectance library of selected biotic and abiotic coral reef features in Heron Reef
No full textUnderwater spectral reflectance was measured for selected biotic and abiotic coral reef features of Heron Reef from June 25-30, 2006. Spectral reflectance's of 105 different benthic types were obtained in-situ. An Ocean Optics USB2000 spectrometer was deployed in an custom made underwater housing with a 0.5 m fiber-optic probe mounted next to an artificial light source. Spectral readings were collected with the probe(bear fibre) about 5 cm from the target to ensure that the target would fill the field of view of the fiber optic (FOV diameter ~4.4 cm), as well as to reduce the attenuating effect of the intermediate water (Roelfsema et al., 2006). Spectral readings included for one target included: 1 reading of the covered spectral fibre to correct for instrument noise, 1 reading of spectralon panel mounted on divers wrist to measure incident ambient light, and 8 readings of the target. Spectral reflectance was calculated for each target by first subtracting the instrument noise reading from each other reading. The corrected target readings were then divided by the corrected spectralon reading resulting in spectral reflectance of each target reading. An average target spectral reflectance was calculated by averaging the eight individual spectral reflectance's of the target. If an individual target spectral reflectance was visual considered an outlier, it was not included in the average spectral reflectance calculation. See Roelfsema at al. (2006) for additional info on the methodology of underwater spectra collection
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Georeferenced benthic photoquadrats captured annually from 2002-2017, distributed over Heron Reef flat and slope areas
No full textUnderwater georeferenced photo-transect surveys were conducted at different locations and using slightly different methodologies. Photoquadrats were collected with the purpose of determination of the benthic composition of each photoquadrat for subsequent use as georeferenced field data for calibration and validation purposes of benthic habitat maps derived from remote sensing satellite or airborne imagery. Transect location, direction and depth were chosen to characterise the variation of benthic cover types represented on coral reefs. Photoquadrat interval along the transects was chosen to reflect the resolution of the satellite image data types used.
In principle a diver or snorkeler captures a photoquadrat (approximate 1 m2 footprint) of the bottom along a transect at 2 - 3 m intervals. Images were assigned a GPS coordinate and analysed for benthic composition.
Initially, from 2002 to 2006, divers/snorkelers swam along a 50 m transect tape. Coordinates were recorded at the beginning and end of the tape. Knowing the horizontal distance interval between photoquadrats the coordinates could be approximated for each image.
From 2007 to 2017, divers/snorkelers towed a floating GPS at the surface which was logging position. The coordinates of each photoquadrat were synchronised based on the timestamp of the photoquadrat and the GPS timestamp, using specialised software (e.g. GPS Photo Link www.geospatialexperts.com or DNR Garmin). In principle coordinates of each photoquadrat were interpolated by finding the GPS coordinates that were logged at a set time before and after the photoquadrat was captured. The camera lens provided a 1 m x 1 m footprint, at a 0.5 m height above the benthos using a plumb line. Horizontal distance between photoquadrats was estimated by fin kicks of the surveyor, and corresponded to a surface distance of approximately 2 - 4 m.
For these surveys, the snorkelers traversed a pre-determined transect 250-1000 m in length, varying depending on heterogeneity of the area covered. Divers would conduct 30 min dives along a 5m depth contour, which would be approximately 500-700 m in length
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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