Search results for "Spectral"
showing 10 items of 3116 documents
Validation of a temperature emissivity separation hybrid method from airborne hyperspectral scanner data and ground measurements in the SEN2FLEX fiel…
2008
This paper presents an assessment of the performance of a hybrid method that allows a simultaneous retrieval of land-surface temperature (LST) and emissivity (LSE) from remotely-sensed data. The proposed method is based on a synergistic usage of the split-window (SW) algorithm and the two-temperature method (TTM) and combines the advantages of both procedures while mitigating their drawbacks. The method was implemented for thermal channels 76 (10.56 µm) and 78 (11.72 µm) of the Airborne Hyperspectral Scanner (AHS), which was flown over the Barrax test site (Albacete, Spain) in the second week of July 2005, within the framework of the Sentinel-2 and Fluorescence Experiment (SEN2FLEX) field c…
Extraction of Endmembers from Spectral Mixtures
1999
Abstract Linear spectral mixture modeling (LSMM) divides each ground resolution element into its constituent materials using endmembers which represent the spectral characteristics of the cover types. However, it is difficult to identify and estimate the spectral signature of pure components or endmembers which form the scene, since they vary with the scale and purpose of the study. We propose three different methods to estimate the spectra of pure components from a set of unknown mixture spectra. Two of the methods consist in different optimization procedures based on objective functions defined from the coordinate axes of the dominant factors. The third one consists in the design of a neu…
A Comparative Study and an Evaluation Framework of Multi/Hyperspectral Image Compression
2009
In this paper, we investigate different approaches for multi/hyperspectral image compression. In particular, we compare the classic multi-2D compression approach and two different implementations of 3D approach (full 3D and hybrid) with regards to variations in spatial and spectral dimensions. All approaches are combined with a weighted Principal Component Analysis (PCA) decorrelation stage to optimize performance. For consistent evaluation, we propose a larger comparison framework than the conventionally used PSNR, including eight metrics divided into three families. The results show the weaknesses and strengths of each approach.
The use of vineyard spectral signatures to identify table grape cultivars
2021
Vineyards have characteristic responses to sunlight. The reflectance values at the different wavelengths are typical of vegetation and define its spectral signature. The aim of this work was to determine the spectral signatures of table grape vineyards located in the production area of Robinvale (Victoria, Australia) in order to identify cultivars in the vineyard. Spectral signatures were detected from images in eight bands from the Worldview 3 platform. Spectral signatures for a representative number of plots were extracted using satellite reflectance images for each cultivar. Spectral signatures were also collected in the field, from the same cultivars, with a FieldSpec® HandHeld 2 portab…
A low-cost multispectral imaging system for the characterisation of soil and small vegetation properties using visible and near-infrared reflectance
2022
Current Proximal Sensing technologies are based on multispectral imaging systems able to capture images in a few spectral bands, usually centred in VIS and NIR regions, to derive vegetation indices. However, most of such systems lack an internal radiometric calibration to estimate the actual reflectance of the observed target, making them sensitive to the local radiative environment and requiring a per-session calibration against a reference target. To overcome such dependence, the instrument described adopts an active illumination of the target surface, allowing the monitoring of soil and low vegetation surfaces by a radiometrically pre-calibrated imaging camera. The system, driven by a mi…
Metodo per il monitoraggio di superfici vegetali
2019
Si descrive un metodo da impiegare per la caratterizzazione delle coperture vegetali. A method to be used for the monitoring of vegetation surfaces is described, which includes the use of a device for measuring the spectral reflectance of vegetation using images acquired with a lightening system based on visible and infrared monoband LEDs and including devignetting, image cropping, radiometric calibration procedures and calculation of reflectance values and vegetation indices.
Method for monitoring vegetation ground covers
2020
A method to be used for the monitoring of vegetation surfaces is described, which includes the use of a device for measuring the spectral reflectance of vegetation using images acquired with a lightining system based on visible and infrared monoband LEDs and including devignetting, image cropping, radiometric calibration procedures and calculation of reflectance values and vegetation indices.
Dispositivo per il monitoraggio di superfici vegetali
2017
La presente invenzione si riferisce al settore della diagnostica ambientale poiché fornisce un dispositivo che consente il monitoraggio dello stato fisiologico dei tappeti erbosi e di altre tipologie di coperture naturali che può essere anche impiegato per una accurata caratterizzazione e gestione delle coperture vegetali quali ad esempio campi sportivi, aree verdi naturali o artificiali e il relativo metodo.
Indoor spectroradiometric characterization of plastic litters commonly polluting the Mediterranean Sea: toward the application of multispectral image…
2020
AbstractAround 350 million tonnes of plastics are annually produced worldwide. A remarkable percentage of these products is dispersed in the environment, finally reaching and dispersed in the marine environment. Recent field surveys detected microplastics’ concentrations in the Mediterranean Sea. The most commonly polymers found were polyethylene, polypropylene and viscose, ethylene vinyl acetate and polystyrene. In general, the in-situ monitoring of microplastic pollution is difficult and time consuming. The main goals of this work were to spectrally characterize the most commonly polymers and to quantify their spectral separability that may allow to determine optimal band combinations for…
Immunohistochemistry and multispectral analisys
2009
The use of methods of image analysis has allowed us to make more reliable and reproducible results obtained by immunohistochemistry (IHC). Wider use and simplification of software allowing a colorimetric study has meant that these methods are available to everyone and made it possible to standardize the technique by reliable systems score. Moreover, the introduction in recent years of multispectral image acquisition systems methods has further refined these techniques allowing to avoid artifacts and release the evaluation of the data by the observer.