Search results for "Spectral imaging"
showing 10 items of 311 documents
Aggregation-induced heterogeneities in the emission of upconverting nanoparticles at the submicron scale unfolded by hyperspectral microscopy
2018
Transparent upconverting hybrid nanocomposites are exciting materials for advanced applications such as 3D displays, nanosensors, solar energy converters, and fluorescence biomarkers. This work presents a simple strategy to disperse upconverting b-NaYF4:Yb3+/Er3+ or Tm3+ nanoparticles into low cost, widely used and easy-to-process polydimethylsiloxane (PDMS)-based organic–inorganic hybrids. The upconverting hybrids were shaped as monoliths, films or powders displaying in the whole volume Tm3+ or Er3+ emissions (in the violet/blue and green/red spectral regions, respectively). For the first time, hyperspectral microscopy allows the identification at the submicron scale of differences in the …
Widely Tunable Polarization Modulation Instability in D2O-Filled Microstructured Optical Fiber
2021
Polarization modulation instability (PMI) is a nonlinear effect in which two pump photons with identical polarization propagating in a nonlinear medium give rise to two new photons of different frequency and orthogonal polarization with respect to the pump photons [1] . In this work, we report the experimental demonstration of broad spectral tuning of PMI generated in solid-core microstructured optical fibers (MOF) that were previously infiltrated with heavy water (D 2 O). MOFs were designed and fabricated with the appropriate dispersion characteristics to produce widely spaced PMI spectral bands when they were filled with D 2 O and pumped at 1064 nm. Heavy water was chosen due to suitable …
Combined multi-wavelength laser speckle contrast imaging and diffuse reflectance imaging for skin perfusion assessment
2019
Abstract Laser Speckle Contrast Imaging (LSCI) is a powerful low-cost method for visualization of flow, microcirculation and blood perfusion. Due to the fact that diseased and healthy tissues has different blood perfusion, LSCI can be a perspective tool for cancer diagnostics and discrimination between different types of tissues. Previously, multispectral diffuse reflectance imaging method for melanoma diagnostics has been introduced. In this work, multi-wavelength (532-, 655- and 850- nm) LSCI technique combined with hyperspectral camera and diffuse reflectance imaging method will be used for assessment of tissues with different skin perfusion properties. An in vivo experiment with occlusi…
Analysis of human skin hyper-spectral images by non-negative matrix factorization
2011
International audience; This article presents the use of Non-negative Matrix Factorization, a blind source separation algorithm, for the decomposition of human skin absorption spectra in its main pigments: melanin and hemoglobin. The evaluated spectra come from a Hyper-Spectral Image, which is the result of the processing of a Multi-Spectral Image by a neural network-based algorithm. The implemented source separation algorithm is based on a multiplicative coeffi cient upload. The goal is to represent a given spectrum as the weighted sum of two spectral components. The resulting weighted coefficients are used to quantify melanin and hemoglobin content in the given spectra. Results present a …
Use of Guided Regularized Random Forest for Biophysical Parameter Retrieval
2018
This paper introduces a feature selection method based on random forest -the Guided Regularized Random Forest (GRRF)- which can be used in classification and regression tasks. The method is based on the regularization of the information gain in the random forest nodes to obtain a subset of relevant and non-redundant features. The proposed method is used as a preliminary step In the process of retrieving biophysical parameters from a hyperspectral image. Preliminary experiments show that we can reduce the RMSE of the retrievals by around 7% for the Leaf Area Index and around 8% for the fraction of vegetation cover when compared to the results using random forest features.
Performance of TES method over urban areas at a high spatial resolution scale
2013
The Temperature and Emissivity Separation (TES) algorithm is used to retrieve the LSE and LST values from hyperspectral sensors. In this work we analyse the performance of this methodology over urban areas. Three different sources of error in the processing chain of the remote sensing imagery are detected: the algorithm itself, the atmospheric correction and the 3D structure of the urban scenes. The TITAN tool is used to model all the radiative components of the signal registered by a sensor. Results show that: first, the TES algorithm used reproduces the LSE (LST) of urban materials within an RMSE of 0.017 (0.9 K). Second, 20 % of uncertainty in the water vapour content of the total atmosp…
Synergetic exploitation of the Sentinel-2 missions for validating the Sentinel-3 ocean and land color instrument terrestrial chlorophyll index over a…
2019
Continuity to the Medium Resolution Imaging Spectrometer (MERIS) Terrestrial Chlorophyll Index (MTCI) will be provided by the Ocean and Land Color Instrument (OLCI) on-board the Sentinel-3 missions. To ensure its utility in a wide range of scientific and operational applications, validation efforts are required. In the past, direct validation has been constrained by the need for costly airborne hyperspectral data acquisitions, due to the lack of freely available high spatial resolution imagery incorporating appropriate spectral bands. The Multispectral Instrument (MSI) on-board the Sentinel-2 missions now offers a promising alternative. We explored the synergetic use of MSI data for validat…
Mapping sub-pixel burnt percentage using AVHRR data. Application to the Alcalaten area in Spain
2010
The purpose of this work is to estimate at sub-pixel scale the percentage of burnt land using the Advanced Very High Resolution Radiometer AVHRR through a simple approach. This methodology is based on multi-temporal spectral mixture analysis MSMA, which uses a normalized difference vegetation index NDVI and a land-surface temperature LST image as input bands. The area of study is located in the Alcalaten region in Castellon Spain, a typical semi-arid Mediterranean region. The results have shown an extension of approximately 55 km2 affected by fire, which is only 5% lower than the statistic reports provided by the Environmental Ministry of Spain. Finally, we include a map of the area showing…
Hyperspectral solar spectral measurements and applications
2007
Measurements of hyperspectral solar irradiance from aircraft and satellite are applied to a variety of cloud and aerosol remote sensing, and radiative energy budget applications.
Actual evapotranspiration estimation by means of airborne and satellite remote sensing data
2006
ABSTRACT During the last the two decades, the scientific community developed detailed mathematical models for simulating land surface energy fluxes and crop evapotrans piration rates by means of a energy ba lance approach. These models can be applied in large areas and with a spatial distributed approach using surface brightness temperature and some ancillary data retrieved from satellite/airborne remote sensed imagery. In this paper a district scale application in combination with multispectral (LandaSat 7 TM data) and hyperspectral airborne MIVIS data has been carried out to test the potentialities of two different energy balance models to estimate evapotranspiration fluxes from a set of …