Search results for "reflectance"
showing 10 items of 161 documents
Retrieval of sun-induced fluorescence using advanced spectral fitting methods
2015
Abstract The FLuorescence EXplorer (FLEX) satellite mission, candidate of ESA's 8th Earth Explorer program, is explicitly optimized for detecting the sun-induced fluorescence emitted by plants. It will allow consistent measurements around the O2-B (687 nm) and O2-A (760 nm) bands, related to the red and far-red fluorescence emission peaks respectively, the photochemical reflectance index, and the structural-chemical state variables of the canopy. The sun-induced fluorescence signal, overlapped to the surface reflected radiance, can be accurately retrieved by employing the powerful spectral fitting technique. In this framework, a set of fluorescence retrieval algorithms optimized for FLEX ar…
Passive Polarimetric Imaging
2014
Passive electro-optical polarimetric imaging is a form of remote sensing in which the properties associated with electromagnetic field orientation are exploited as a means to discriminate between objects in an extended scene. The purpose of this chapter is to introduce some fundamental concepts in the science of imaging polarimetry. These concepts include the Stokes-Mueller description of polarized light, the physical mechanisms that contribute to polarimetric image contrast, a mathematical description of several polarimetric imaging systems, and an example target detection algorithm. Polarimetric image contrast is discussed in terms of reflected, emitted, and scattered light. Special empha…
Apparence des matériaux, Vision artificielle, Inspection qualité, Reflectance Transformation Imaging
2022
Mastering the visual perception of the surfaces of manufactured products is a central issue for industry. However, in industry, the quality of surfaces is often assessed by human inspectors. Only a few specific cases use an instrumental or photometric approach. Among the photometric approaches, one of them is experiencing significant growth: Reflectance Transformation Imaging (RTI). However, this technique has limitations in terms of data acquisition and processing. The objective is therefore to correct some of these limitations in order to improve the RTI and, consequently, the visual quality control of surface conditions in industry.The current RTI systems are limited and cannot meet our …
Assessment of Classifiers and Remote Sensing Features of Hyperspectral Imagery and Stereo-Photogrammetric Point Clouds for Recognition of Tree Specie…
2018
Recognition of tree species and geospatial information on tree species composition is essential for forest management. In this study, tree species recognition was examined using hyperspectral imagery from visible to near-infrared (VNIR) and short-wave infrared (SWIR) camera sensors in combination with a 3D photogrammetric canopy surface model based on RGB camera stereo-imagery. An arboretum with a diverse selection of 26 tree species from 14 genera was used as a test area. Aerial hyperspectral imagery and high spatial resolution photogrammetric color imagery were acquired from the test area using unmanned aerial vehicle (UAV) borne sensors. Hyperspectral imagery was processed to calibrated …
Investigation of modern oil paints through a physico-chemical integrated approach. Emblematic cases from Valencia, Spain
2020
Abstract The study and the characterisation of modern and contemporary oil paintings is still a challenging issue, in particular considering the significant changes in paint production across the 19th and 20th centuries. This paper presents the results of the first physico-chemical integrated study of the artistic materials used in six paintings from the School of Art and Higher Design of Valencia (Escola d'Art i Superior de Disseny, EASD-Valencia), artworks created between 1871 and 1943 by four famous Valencian artists: Salustiano Asenso Arozarena, Salvador Abril I Blasco, Enrique Navas Escuriet and Jose Bellver Delmas. A wide range of inorganic and organic compounds was identified through…
Colours of the « images of the floating world ». non-invasive analyses of Japanese ukiyo-e woodblock prints (18th and 19th centuries) and new contrib…
2019
Abstract In the Edo (1615–1868) and Meiji (1868–1912) periods, Japanese woodblock prints were a commercial form of art that reproduced the everyday life of ordinary people (the ukiyo-e style). Since different dyes and pigments were used to produce these prints, changing over time, the knowledge of these materials can be very important for the history and the conservation of ukiyo-e prints. This study will present the results of the investigation of several woodblock prints, produced between the 18th and 19th centuries. The artworks belong to the Asian art collection at the Museum of Zaragoza (Spain). The aim of the study is the identification of organic colorants and inorganic pigments empl…
Prototyping algorithm for retrieving FAPAR using MSG data in the context of the LSA SAF project
2007
This paper describes the prototyping algorithm developed for retrieving the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) using MSG data in the framework of satellite application facility on land surface analysis (LSA SAF). The prototyping relies on the Roujean and Breon (1995) method, which is based on simulations of visible and near infrared reflectance values in an optimal geometry. A relationship is found between a vegetation index and daily FAPAR The algorithm has been applied to one year of MSG BRDF data since August 2005, using a temporal frequency of 5-days, and then validated against a set of operational satellite FAPAR products such as MODIS, MERIS, SeaWiFS and …
Quantitative Multispectral Imaging Differentiates Melanoma from Seborrheic Keratosis.
2021
Melanoma is a melanocytic tumor that is responsible for the most skin cancer-related deaths. By contrast, seborrheic keratosis (SK) is a very common benign lesion with a clinical picture that may resemble melanoma. We used a multispectral imaging device to distinguish these two entities, with the use of autofluorescence imaging with 405 nm and diffuse reflectance imaging with 525 and 660 narrow-band LED illumination. We analyzed intensity descriptors of the acquired images. These included ratios of intensity values of different channels, standard deviation and minimum/maximum values of intensity of the lesions. The pattern of the lesions was also assessed with the use of particle analysis. …
Time Series Corrections and Analyses in Thermal Remote Sensing
2013
The time span of surface thermal data bases now reaches a few decades. However, studies using surface thermal time series are seldom, due to the difficulty of obtaining temporally coherent estimations for this parameter. Applications for surface thermal multitemporal analysis range from climate change studies and modeling to anomaly detection for natural or industrial hazard detection. This chapter presents methods to improve the temporal coherence of temperature time series, through data reconstruction of atmospheric and cloud contaminated observations, and through the correction of the orbital drift effect which hinders the use of the longest data sets. Then, methods for the analysis of t…
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…