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Academic literature on the topic 'Reflectance'

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Published: 4 June 2021
Last updated: 14 September 2024

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Journal articles on the topic "Reflectance"

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Ahmad, Noraini, Sabarinah Sh Ahmad, and Anuar Talib. "Surface Reflectance for Illuminance Level Control in Daylit Historical Museum Gallery under Tropical Sky Conditions." Advanced Materials Research 610-613 (December 2012): 2854–58. http://dx.doi.org/10.4028/www.scientific.net/amr.610-613.2854.

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Malaysia has tropical sky conditions, receiving plenty of natural light throughout the year. Natural light fluctuates greatly and it can be rather tricky to provide good distribution of daylight throughout an interior space and this prompts the need for strategic daylight control programme in a historic museum gallery. Surface reflectance is a significant design consideration, particularly with regards to how light is distributed throughout an interior space. Research on how the internal surfaces reflectances are controlled for long-term preservation of museum exhibits is still lacking for tropical skies conditions. The study aims to assess the internal surface reflectance contribution at a west facing daylit historical museum gallery through in-situ measurements and simulation model assessment. The results obtained in these experiments are visually compared with the existing surface reflectance values through simulation modelling. The results show new knowledge on light damage issues. The results also highlight daylighting distributions control and light exposure limits through realistic predictions’ images and reflectance’s alterations. The study confirms that surface reflectances can be a control mechanism for preventive conservation in the historical museum gallery.
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Hedley, John, Maryam Mirhakak, Adam Wentworth, and Heidi Dierssen. "Influence of Three-Dimensional Coral Structures on Hyperspectral Benthic Reflectance and Water-Leaving Reflectance." Applied Sciences 8, no. 12 (December 19, 2018): 2688. http://dx.doi.org/10.3390/app8122688.

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Shading and inter-reflections created by the three-dimensional coral canopy structure play an important role on benthic reflectance and its propagation above the water. Here, a plane parallel model was coupled with a three-dimensional radiative transfer canopy model, incorporating measured coral shapes and hyperspectral benthic reflectances, to investigate this question under different illumination and water column conditions. Results indicated that a Lambertian treatment of the bottom reflectance can be a reasonable assumption if a variable shading factor is included. Without flexibility in the shading treatment, nadir view bottom reflectances can vary by as much as ±20% (or ±9% in above-water remote sensing reflectance) under solar zenith angles (SZAs) up to 50°. Spectrally-independent shading factors are developed for benthic coral reflectance measurements based on the rugosity of the coral. In remote sensing applications, where the rugosity is unknown, a shading factor could be incorporated as an endmember for retrieval in the inversion scheme. In dense coral canopies in clear shallow waters, the benthos cannot always be treated as Lambertian, and for large solar-view angles the bi-directional reflectance distribution functions (BRDF) hotspot propagated to above water reflectances can create up to a 50% or more difference in water-leaving reflectances, and discrepancies of 20% even for nadir-view geometries.
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Lu, Xiaomei, Yongxiang Hu, Yuekui Yang, Mark Vaughan, Zhaoyan Liu, Sharon Rodier, William Hunt, Kathy Powell, Patricia Lucker, and Charles Trepte. "Laser pulse bidirectional reflectance from CALIPSO mission." Atmospheric Measurement Techniques 11, no. 6 (June 8, 2018): 3281–96. http://dx.doi.org/10.5194/amt-11-3281-2018.

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Abstract. This paper presents an innovative retrieval method that translates the CALIOP land surface laser pulse returns into the surface bidirectional reflectance. To better analyze the surface returns, the CALIOP receiver impulse response and the downlinked samples' distribution at 30 m vertical resolution are discussed. The saturated laser pulse magnitudes from snow and ice surfaces are recovered based on information extracted from the tail end of the surface signal. The retrieved snow surface bidirectional reflectance is compared with reflectance from both CALIOP cloud-covered regions and MODIS BRDF–albedo model parameters. In addition to the surface bidirectional reflectance, the column top-of-atmosphere bidirectional reflectances are calculated from the CALIOP lidar background data and compared with the bidirectional reflectances derived from WFC radiance measurements. The retrieved CALIOP surface bidirectional reflectance and column top-of-atmosphere bidirectional reflectance results provide unique information to complement existing MODIS standard data products and are expected to have valuable applications for modelers.
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Leckie, D. G., D. P. Ostaff, P. M. Teillet, and G. Fedosjevs. "Spectral Characteristics of Tree Components of Balsam Fir and Spruce Damaged by Spruce Budworm." Forest Science 35, no. 2 (June 1, 1989): 582–600. http://dx.doi.org/10.1093/forestscience/35.2.582.

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Abstract Spectral reflectances from 360 to 1100 nm at 5 nm intervals in 6 nm bands were measured with a laboratory spectrometer for samples of the components of balsam fir and white spruce trees defoliated by the spruce budworm. These components included current-year needles, 1-year-old needles, 2-year and older needles, budworm feeding debris, twigs, bark, and lichen. Current-year needles had significantly higher reflectances than older needles in the green and yellow parts of the spectrum. Feeding debris, which is visually red, had a smooth spectral curve of increasing reflectance with wavelength. The greatest difference between needles and feeding debris was in the short near-infrared wavelengths and at the chlorophyll absorption maximum near 670 nm. The reflectance of twigs and bark changed with age and exposure to weathering. Variability in their reflectance was large. There were no distinct narrow band features of twig or feeding debris reflectance, which would be characteristic of defoliation. Lichen is highly reflective, and its presence on branches of defoliated trees will greatly alter branch reflectance characteristics. Changes in spectral reflectance of trees throughout the various stages of a spruce budworm outbreak depend on a complex interrelationship of the reflectances of individual components which, in turn, are complex and changing. For. Sci. 35(2):582-600.
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Winther, Jan-Gunnar. "Spectral bi-directional reflectance of snow and glacier ice measured in Dronning Maud Land, Antarctica." Annals of Glaciology 20 (1994): 1–5. http://dx.doi.org/10.3189/1994aog20-1-1-5.

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Visible and near-infrared spectral reflectances of snow and superimposed ice were measured in Dronning Maud Land, Antarctica, during the 1992-93 austral summer. Spectral-reflectance curves of both snow and superimposed ice remain high ( > 80%) in the visible region. A pronounced decrease in reflectance appears in the near-infrared, especially for superimposed ice. Superimposed ice with a 1 cm thick surface layer of ice-bound snow crystals had a considerably higher reflectance than superimposed ice containing only a few snow crystals. Furthermore, these data prove that snow and superimposed ice reflect solar radiation specularly and suggest that the anisotropy strengthens with increasing wavelengths. Integrated in-situ reflectances corresponding to Landsat TM bands 1-4 show that TM band 1 is least affected, whereas TM band 4 is most affected by anisotropy. Furthermore, the anisotropy increases with increasing off-nadir viewing angles up to an angle corresponding to 90°-θs(θs= solar elevation). For a 15° off-nadir sensor-observation angle, the average snow reflectance for TM bands 1--4 is about 10% higher than at nadir. Similarly, the apparent reflectance can be more than 50% higher than the nadir reflectance for larger observation angles. Consequently, if satellite-derived reflectances are going to be considered as absolute values, a topographic-correction model is needed to correct for the effects of anisotropy.
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Winther, Jan-Gunnar. "Spectral bi-directional reflectance of snow and glacier ice measured in Dronning Maud Land, Antarctica." Annals of Glaciology 20 (1994): 1–5. http://dx.doi.org/10.1017/s0260305500016141.

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Visible and near-infrared spectral reflectances of snow and superimposed ice were measured in Dronning Maud Land, Antarctica, during the 1992-93 austral summer. Spectral-reflectance curves of both snow and superimposed ice remain high ( > 80%) in the visible region. A pronounced decrease in reflectance appears in the near-infrared, especially for superimposed ice. Superimposed ice with a 1 cm thick surface layer of ice-bound snow crystals had a considerably higher reflectance than superimposed ice containing only a few snow crystals. Furthermore, these data prove that snow and superimposed ice reflect solar radiation specularly and suggest that the anisotropy strengthens with increasing wavelengths. Integrated in-situ reflectances corresponding to Landsat TM bands 1-4 show that TM band 1 is least affected, whereas TM band 4 is most affected by anisotropy. Furthermore, the anisotropy increases with increasing off-nadir viewing angles up to an angle corresponding to 90°-θs(θs= solar elevation). For a 15° off-nadir sensor-observation angle, the average snow reflectance for TM bands 1--4 is about 10% higher than at nadir. Similarly, the apparent reflectance can be more than 50% higher than the nadir reflectance for larger observation angles. Consequently, if satellite-derived reflectances are going to be considered asabsolutevalues, a topographic-correction model is needed to correct for the effects of anisotropy.
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Liao, Hsien-Shun, Ya-Kang Huang, Jian-Yuan Syu-Gu, and En-Te Hwu. "Real-Time Reflectance Measurement Using an Astigmatic Optical Profilometer." Sensors 22, no. 16 (August 19, 2022): 6242. http://dx.doi.org/10.3390/s22166242.

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An astigmatic optical profilometer with a commercial optical pickup head provides benefits, such as high resolution, compact size, and low cost. To eliminate artifacts caused by complex materials with different reflectances, a z-axis modulation mode is proposed to obtain quantitative surface morphology by measuring S curves on all image pixels. Moreover, the slope of the linear region in the S curve shows a positive relationship with the surface reflectance. However, the slope was calculated using an offline curve fitting method, which did not allow real-time reflectance imaging. Furthermore, quantitative reflectance data were unavailable because of the lack of calibration. In this study, we propose a novel method for real-time reflectance imaging by measuring the amplitude of a focus error signal (FES). The calibration results displayed a linear relationship between the FES amplitude and reflectance. The reflectance image of a grating sample with chrome patterns on a glass substrate demonstrates accurate reflectance measurements with a micrometer spatial resolution.
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Gene, Jinhwa, Min Yong Jeon, and Sun Do Lim. "Reflectometers for Absolute and Relative Reflectance Measurements in the Mid-IR Region at Vacuum." Sensors 21, no. 4 (February 7, 2021): 1169. http://dx.doi.org/10.3390/s21041169.

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We demonstrated spectral reflectometers for two types of reflectances, absolute and relative, of diffusely reflecting surfaces in directional-hemispherical geometry. Both are built based on the integrating sphere method with a Fourier-transform infrared spectrometer operating in a vacuum. The third Taylor method is dedicated to the reflectometer for absolute reflectance, by which absolute spectral diffuse reflectance scales of homemade reference plates are realized. With the reflectometer for relative reflectance, we achieved spectral diffuse reflectance scales of various samples including concrete, polystyrene, and salt plates by comparing against the reference standards. We conducted ray-tracing simulations to quantify systematic uncertainties and evaluated the overall standard uncertainty to be 2.18% (k = 1) and 2.99% (k = 1) for the absolute and relative reflectance measurements, respectively.
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Henniger, Hans, Friedrich J. Bohn, Kim Schmidt, and Andreas Huth. "A New Approach Combining a Multilayer Radiative Transfer Model with an Individual-Based Forest Model: Application to Boreal Forests in Finland." Remote Sensing 15, no. 12 (June 12, 2023): 3078. http://dx.doi.org/10.3390/rs15123078.

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To understand forest dynamics under today’s changing environmental conditions, it is important to analyze the state of forests at large scales. Forest inventories are not available for all regions, so it is important to use other additional methods, e.g., remote sensing observations. Increasingly, remotely sensed data based on optical instruments and airborne LIDAR are becoming widely available for forests. There is great potential in analyzing these measurements and gaining an understanding of forest states. In this work, we combine the new-generation radiative transfer model mScope with the individual-based forest model FORMIND to generate reflectance spectra for forests. Combining the two models allows us to account for species diversity at different height layers in the forest. We compare the generated reflectances for forest stands in Finland, in the region of North Karelia, with Sentinel-2 measurements. We investigate which level of forest representation gives the best results and explore the influence of different calculation methods of mean leaf parameters. For the majority of the forest stands, we generated good reflectances with all levels of forest representation compared to the measured reflectance. Good correlations were also found for the vegetation indices (especially NDVI with R2=0.62). This work provides a forward modeling approach for relating forest reflectance to forest characteristics. With this tool, it is possible to analyze a large set of forest stands with corresponding reflectances. This opens up the possibility to understand how reflectance is related to succession and different forest conditions.
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Yamada, Takatoshi, Makoto Hisa, and Masataka Hasegawa. "Optical properties of vertically aligned graphene sheets." MRS Advances 2, no. 02 (2017): 77–82. http://dx.doi.org/10.1557/adv.2017.16.

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ABSTRACT We have developed deposition of vertically aligned graphene sheets on Cu foils by surface wave microwave plasma CVD and the transfer from Cu foil to quartz substrate to evaluate optical reflectances and transmittances of the inherent vertical aligned graphene sheets. Both reflectance and transmittance spectra are almost independent of incident angles in the range between 300 and 800nm. The reflectance is lower than 0.067%, which is lower than those of the commercial black alumite plate. The transmittances are less than the detection limit of the system. It is considered that the obtained low reflectance is attributed to the unique structure of the vertically aligned graphene sheets.
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Dissertations / Theses on the topic "Reflectance"

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Ibbett, R. N. "Infrared diffuse reflectance spectroscopy." Thesis, University of East Anglia, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382895.

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Evens, Anne F. "Spectral reflectance of vitrinite." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311095.

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Chen, Qiao. "Modelling of spectral reflectance." Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438575.

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Feng, Xiaofan. "Comparison of methods for generation of absolute reflectance factor measurement for BRDF studies /." Online version of thesis, 1990. http://hdl.handle.net/1850/10922.

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Beigpour, Shida. "Illumination and Object Reflectance Modeling." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/113551.

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El modelado de la reflectancia de las superficies es una clave importante para la comprensión de escenas. Un modelo de reflectancia preciso, basado en las leyes de la física, nos permite alcanzar resultados realísticos y físicamente plausibles. Además, el uso de tal modelo nos permite establecer un conocimiento más profundo acerca de la interacción de la luz con las superficies de los objetos, y resulta crucial para una variedad de aplicaciones de visión por computador. Debido a la alta complejidad de los modelos de reflectancia, la gran mayoría de las aplicaciones existentes de visión por computador basan sus métodos en suposiciones simplificadoras, tales como la reflectancia lambertiana o la iluminación uniforme para ser capaz de resolver sus problemas. Sin embargo, en escenas del mundo real, los objetos tienden a exhibir reflexiones más complejas (difusas y especulares), y además se ven afectados por las características y la cromaticidad de los iluminantes. En esta tesis, se incorpora un modelo de reflexión más realista para aplicaciones de visión por computador. Para abordar tal fenómeno físico complejo, extendemos los modelos de reflectancia de los objetos del estado-del-arte mediante la introducción de un Modelo de Reflexión Dicromático Multi-Iluminante (MIDR). Usando MIDR somos capaces de modelar y descomponer la reflectancia de un objeto con especularidades complejas bajo múltiples iluminantes que presentan sombras e interreflexiones. Se demuestra que este modelo nos permite realizar una recolorización realista de los objetos iluminados por luces de colores y múltiples iluminantes. Además se propone un método "local" de estimación del iluminante para modelar las escenas con iluminación no uniforme (por ejemplo, una escena al aire libre con un cielo azul y un sol amarillo, una escena interior con iluminación combinada con la iluminación al aire libre a través de una ventana, o cualquier otro caso en el que dos o más luces con diferentes colores iluminan diferentes partes de la escena). El método propuesto aprovecha un modelo probabilístico basado en grafos y resuelve el problema rededefiniendo la estimación como un problema de minimización de energía. Este método nos proporciona estimaciones locales del iluminante que mejoran en gran medida a los métodos del estado-del-arte en constancia de color. Por otra parte, hemos capturado nuestro propia base de datos multi-iluminante, que consiste de escenas complejas y condiciones de iluminación al aire libre o de laboratorio. Con ésta se demuestra la mejora lograda usando nuestro método con respecto a los métodos del estado-del-arte para la estimación automática del iluminante local. Se demuestra que tener un modelo más realista y preciso de la iluminación de la escena y la reflectancia de los objetos, mejora en gran medida la calidad en muchas tareas de visión por ordenador y gráficos por computador. Mostramos ejemplos de mejora en el balance automático de blanco, reiluminación de escenas y en la recolorización de objetos. La teoría propuesta se puede emplear también para mejorar la denominación automática de colores, la detección de objetos, el reconocimiento y la segmentación, que están entre las tendencias más populares de la visión por computador.
Surface reflectance modeling is an important key to scene understanding. An accurate reflectance model which is based on the laws of physics allows us to achieve realistic and physically plausible results. Using such model, a more profound knowledge about the interaction of light with objects surfaces can be established which proves crucial to variety of computer vision application. Due to high complexity of the reflectance model, the vast majority of the existing computer vision applications base their methods on simplifying assumptions such as Lambertian reflectance or uniform illumination to be able to solve their problem. However, in real world scenes, objects tend to exhibit more complex reflections (diffuse and specular) and are furthermore affected by the characteristics and chromaticity of the illuminants. In this thesis, we incorporate a more realistic reflection model in computer vision applications. To address such complex physical phenomenon, we extend the state-of-the-art object reflectance models by introducing a Multi-Illuminant Dichromatic Reflection model (MIDR). Using MIDR we are able to model and decompose the reflectance of an object with complex specularities under multiple illuminants presenting shadows and inter-reflections. We show that this permits us to perform realistic re-coloring of objects lit by colored lights, and multiple illuminants. Furthermore, we propose a “local” illuminant estimation method in order to model the scenes with non-uniform illumination (e.g., an outdoor scene with a blue sky and a yellow sun, a scene with indoor lighting combined with outdoor lighting through a window, or any other case in which two or more lights with distinct colors illuminating different parts of the scene). The proposed method takes advantage of a probabilistic and graph-based model and solves the problem by re-defining the estimation problem as an energy minimization. This method provides us with local illuminant estimations which improve greatly over state-of-the-art color constancy methods. Moreover, we captured our own multi-illuminant dataset which consists of complex scenes and illumination conditions both outdoor and in laboratory conditions. We show improvement achieved using our method over state-of-the-art methods for local illuminant estimation. We demonstrate that having a more realistic and accurate model of the scene illumination and object reflectance greatly improves the quality of many computer vision and computer graphics tasks. We show examples of improved automatic white balance, scene relighting, and object re-coloring. The proposed theory can be employed in order to improve color naming, object detection, recognition, and segmentation which are among the most popular computer vision trends.
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Bernhardsson, Daniel, and Johan Törne. "Video Neutralization and Reflectance Spoofing." Thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-97756.

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We present two new applications for projector-camera systems; reflectance spoofing and video neutralization. With these applications we can project visual content in mixel reality environments without making the light levels unnatural and we can project color compensated movies and images on non-ideal projection surfaces. A custom developed structured light technique is used to calibrate the correspondence between camera pixels and projector pixels. A feedback algorithm is used to establish a neutralization image on a per pixel basis. Our results show real promise for this kind of technology. A new method for spectral calibration of digital cameras is also presented. The method uses laser pointers to mark wavelengths in a spectrum created with a tungsten light source and a diffraction grating. The method is faster and potentially much cheaper than current methods and our results suggest that the method gives results of better or equal quality compared to currently availible methods.
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Blount, Christopher. "Near infrared reflectance in Anura." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/near-infrared-reflectance-in-anura(f730de01-8d4a-43de-b2dd-2ef3027bfc2f).html.

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Increased near infrared (NIR) reflection, closely resembling the red edge found in leaves, has been known in frogs for many years. Whereas previously thought of as an isolated rarity, we have shown that it is likely far more prevalent than previously believed, occurring in multiple distinct family groups and world regions. To date, there are now 26 anuran species known to demonstrate increased NIR reflectance, from 12 different genera, 4 families, and 3 ecozones. The visible/NIR reflection spectra of each individual measured was found to be characteristic of its species; whether it was wild or captive bred; and its sex. A machine learning based classification system was demonstrated as a viable method of identifying these properties from a frog's reflection spectra alone. How this reflection spectra developed from a pre-metamorphosis froglet through to adult frog was tracked, with the gradual changes to the reflection spectra of both NIR reflective and other frogs identified as being most likely dominated by the reduction in epidermal melanophores, and the increasing number of dermal iridophores. A modified consumer camera was shown to be a viable method for rapid identification of increased NIR reflection in anurans, and was used to identify that salamanders also show variation in NIR reflection between ground dwelling and leaf sitting species. The overnight colour change in Hylomantis lemur was observed, and found to occur pre-emptively of the frog's future location; with the frogs regularly transitioning from pale green ‘daytime' colouration, to the dark brown ‘night time' colouration, while still on the green leaf surface before becoming active, and undertaking the reverse transition while still active, but shortly before returning to the leaf. It seems likely that this change is for protection from silhouetting whilst active. Optical coherence tomography images were taken of several species of frog, and found to be a viable method for non-invasive investigation of anuran skin structure, with structural differences observed between the two colourations of H. lemur. It was found that the most likely cause of the increased NIR reflection in frogs is a reduction in melanin, either by absence or substitution with pterorhodin. Although the true benefit to the frog is difficult to determine, it seems likely that cryptic thermoregulation plays a key role: the maintenance of body temperature for the purpose of camouflage from animals capable of far-infrared vision. This thesis demonstrates the legitimacy of several techniques and approaches for non-invasive study of anurans, but the ultimate scope of the project is fundamentally limited by the range of frogs available. Further insight is likely to arise from increasing this scope, applying these techniques to more frogs, from more species, in more regions, and the author wishes all future researchers the greatest success in this endeavour.
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Matusik, Wojciech 1973. "A data-driven reflectance model." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/87454.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.
"September 2003."
Includes bibliographical references (leaves 112-115).
I present a data-driven model for isotropic bidirectional reflectance distribution functions (BRDFs) based on acquired reflectance data. Instead of using analytic reflectance models, each BRDF is represented as a dense set of measurements. This representation allows interpolation and extrapolation in the space of acquired BRDFs to create new BRDFs. Each acquired BRDF is treated as a single high-dimensional vector taken from the space of all possible BRDFs. Both linear (subspace) and non-linear (manifold) dimensionality reduction tools are applied in an effort to discover a lower-dimensional representation that characterizes the acquired BRDFs. To complete the model, users are provided with the means for defining perceptually meaningful parametrizations that allow them to navigate in the reduced-dimension BRDF space. On the low-dimensional manifold, movement along these directions produces novel, but valid, BRDFs. By analyzing a large collection of reflectance data, I also derive two novel reflectance sampling procedures that require fewer total measurements than standard uniform sampling approaches. Using densely sampled measurements the general surface reflectance function is analyzed to determine the local signal variation at each point in the function's domain. Wavelet analysis is used to derive a common basis for all of the acquired reflectance functions, as well as a non-uniform sampling pattern that corresponds to all non-zero wavelet coefficients. Second, I show that the reflectance of an arbitrary material can be represented as a linear combination of the surface reflectance functions. Furthermore, this analysis specifies a reduced set of sampling points that permits the robust estimation of the coefficients of this linear combination.
(cont.) These procedures dramatically shorten the acquisition time for isotropic reflectance measurements.
by Wojciech Matusik.
Ph.D.
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Randeberg, Lise Lyngsnes. "Diagnostic applications of diffuse reflectance spectroscopy." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-691.

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This thesis covers a wide field of applications, with an emphasis on applications of reflectance spectroscopy for diagnostic purposes. Reflectance spectroscopy in the visible part of the spectrum has been proved to be a valuable tool in a variety of applications including e. g. port-wine stain diagnostics, diagnostics of liver pathology, neonatal jaundice and age determination of bruises for forensic applications.

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Chou, Ti-Fan. "Obtaining reflectance functions using digital cameras." Thesis, University of Leeds, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.634750.

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Spectral reflectance is the 'finger print' of the colour of an object. This study investigated a number of the methods to obtain spectral reflectance functions of colours, and to compare their performance. Spectrophotometers are traditionally colour measurement instruments. However, they can only measure one spot of flat uniform colour patches with direct contact. Using digital cameras as a means of colour measurement device to predict spectral reflectance can overcome this limitation, but system performance in terms of accuracy and precision is expected to be lower than using spectrophotometers. In the present work, the metrology and prediction of measuring colours were studied. The former included the evaluation of spectrophotometer performance. The latter considered characterisation models using digital cameras to predict spectral reflectance from camera responses. Large efforts were spent to develop camera based technology. The characterisation model which was typically applied to transform the camera primary responses to device independent primaries (XYZ or CIELAB) requires a characterisation target. To make a successful model depends upon the selection of effective colours in the characterisation target. In the present research, a method for developing the characterisation target and the importance of colour regions for colour selection were proposed.
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Books on the topic "Reflectance"

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J, Hsia J., ed. Spectral reflectance. Gaithersburg, MD: U.S. Dept. of Commerce, National Bureau of Standards, 1987.

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2

A, Early Edward, Parr A. C, and National Institute of Standards and Technology (U.S.), eds. Spectral reflectance. Gaithersburg, MD: U.S. Dept. of Commerce, Technology Administration, National Institute of Standards and Technology, 1998.

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Bogdanowicz, Janusz. Photomodulated Optical Reflectance. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-30108-7.

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4

Ibbett, Roger Norman. Infrared diffuse reflectance spectroscopy. Norwich: University of East Anglia, 1988.

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Weidner, Victor R. NBS measurement services: Spectral reflectance. Washington, D.C: National Bureau of Standards, 1987.

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Raja, Sekhar B. N., and Bhabha Atomic Research Centre, eds. A laboratory experimental setup for reflectivity experiments. Mumbai: Bhabha Atomic Research Centre, 1999.

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Hofmann-Wellenhof, Rainer, Giovanni Pellacani, Joseph Malvehy, and Hans Peter Soyer, eds. Reflectance Confocal Microscopy for Skin Diseases. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-21997-9.

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Mukhopadhyay, Prasanta K., and Wallace G. Dow, eds. Vitrinite Reflectance as a Maturity Parameter. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1994-0570.

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Winston, Richard B. Vitrinite reflectance of Alabama's bituminous coal. Tuscaloosa, Ala: Geological Survey of Alabama, 1990.

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Pittsburgh Research Center (United States. Dept. of Energy), ed. Moisture-corrected reflectance rock dust meter. [Pittsburgh, PA]: U.S. Dept. of Energy, Pittsburgh Research Center, 1996.

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Book chapters on the topic "Reflectance"

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Gooch, Jan W. "Reflectance." In Encyclopedic Dictionary of Polymers, 613. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_9848.

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Weik, Martin H. "reflectance." In Computer Science and Communications Dictionary, 1445. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/1-4020-0613-6_15826.

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Gooch, Jan W. "Diffuse Reflectance." In Encyclopedic Dictionary of Polymers, 220. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_3653.

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Gooch, Jan W. "Directional Reflectance." In Encyclopedic Dictionary of Polymers, 234. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_3810.

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Gooch, Jan W. "Reflectance, Absolute." In Encyclopedic Dictionary of Polymers, 613. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_9849.

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Gooch, Jan W. "Reflectance, Diffuse." In Encyclopedic Dictionary of Polymers, 614. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_9850.

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Gooch, Jan W. "Reflectance, Directional." In Encyclopedic Dictionary of Polymers, 614. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_9851.

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Gooch, Jan W. "Reflectance Factor." In Encyclopedic Dictionary of Polymers, 614. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_9852.

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Gooch, Jan W. "Reflectance, Fresnel." In Encyclopedic Dictionary of Polymers, 614. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_9853.

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Gooch, Jan W. "Reflectance, Hemispherical." In Encyclopedic Dictionary of Polymers, 614. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_9854.

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Conference papers on the topic "Reflectance"

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De Zeeuw, Michael, and Aswin C. Sankaranarayanan. "Scanning Iridescent Reflectance." In 2024 IEEE International Conference on Computational Photography (ICCP), 1–12. IEEE, 2024. http://dx.doi.org/10.1109/iccp61108.2024.10644223.

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Verly, P. G., and G. Duplain. "Design of Fully Shaped Graded Reflectance Mirrors With Phase Control." In Optical Interference Coatings. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oic.1992.omb2.

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Dielectric graded reflectance mirrors (GRMs) with a gaussian or supergaussian radial variation of the reflectance are known to reduce significantly the detrimental effects of hard edge diffraction in unstable laser resonators. Different types of GRMs consisting of a single graded thickness layer incorporated in a conventional multilayer system have been demonstrated. Such mirrors are beginning to be offered, in moderate reflectances, by major manufacturers for use in high gain lasers.
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Hoffman, Naty. "Reflectance." In ACM SIGGRAPH 2006 Courses. New York, New York, USA: ACM Press, 2006. http://dx.doi.org/10.1145/1185657.1185756.

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Sewall, Laura, and Daniel Kersten. "Limits to lightness constancy." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/oam.1986.tuh2.

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The limits to lightness constancy can be measured by the accuracy with which human observers estimate the reflectance of an object as a function of various illumination conditions. Our paradigm is analogous to traditional psychophysical methods used for signal identification, with the reflectance representing the signal and the illumination serving as noise. We used computer graphic techniques to simulate monochrome scenes consisting of a plane grid of square pieces of paper with various initial reflectances. The squares were then non-uniformly illuminated. We measured the ability of observers to correctly identify the reflectance of a randomly chosen patch by selecting a matching piece of paper from a standard palette, also simulated. Performance was measured as a function of the number of patches, number of possible reflectance values, illumination contrast, and illumination spatial spectrum. With uniform illumination, observers could accurately identify only six reflectance values for the three conditions varying in number of patches. However, within this range of reflectance patches, reflectance identification was robust over the range of illumination contrasts and spatial frequencies tested. These results suggest interesting constraints to be considered in the formulation of algorithms for lightness constancy.
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Lv, Jipeng, Heng Guo, Guanying Chen, Jinxiu Liang, and Boxin Shi. "Non-Lambertian Multispectral Photometric Stereo via Spectral Reflectance Decomposition." In Thirty-Second International Joint Conference on Artificial Intelligence {IJCAI-23}. California: International Joint Conferences on Artificial Intelligence Organization, 2023. http://dx.doi.org/10.24963/ijcai.2023/139.

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Multispectral photometric stereo (MPS) aims at recovering the surface normal of a scene from a single-shot multispectral image captured under multispectral illuminations. Existing MPS methods adopt the Lambertian reflectance model to make the problem tractable, but it greatly limits their application to real-world surfaces. In this paper, we propose a deep neural network named NeuralMPS to solve the MPS problem under non-Lambertian spectral reflectances. Specifically, we present a spectral reflectance decomposition model to disentangle the spectral reflectance into a geometric component and a spectral component. With this decomposition, we show that the MPS problem for surfaces with a uniform material is equivalent to the conventional photometric stereo (CPS) with unknown light intensities. In this way, NeuralMPS reduces the difficulty of the non-Lambertian MPS problem by leveraging the well-studied non-Lambertian CPS methods. Experiments on both synthetic and real-world scenes demonstrate the effectiveness of our method.
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Brill, Michael H. "Reflectance ensembles with illuminant-Invariant chromaticity ordering." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/oam.1988.wq6.

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In a color atlas, the uniformity of color spacing between reflectances is disturbed by changes in the spectral power distribution (SPD) of the illumination. Because the atlas may still be useful under different lights, we introduce a new metric of color order that is less sensitive to change of illumination. Three reflectances with labels 1, 2, 3 map to points in chromaticity space (under a particular light) that, if not collinear, are ordered either clockwise or counterclockwise. The ordering parameter P of the reflectances is –1 for clockwise ordering, +1 for counterclockwise ordering, and 0 for collinear points. The perceptual significance of P can be tested via a dichotomous color-blindness test (such as the Farnsworth D-15 test). It has been shown mathematically1 that the P of three reflectances depends on illumination only if, when the reflectances are treated formally as color-matching functions, the chromaticity space that results has a spectrum locus that is not everywhere convex. Illuminants affect P when one or more reflectances is purple—a vindication of the model because purples are known not to be color-constant. A color atlas is called statistically consistent if its first three principal components form a chromaticity space that is convex and well ordered in wavelength. The Munsell atlas is statistically consistent. Convexity of the spectrum locus also insures that no linear combination of the reflectances (or reflectance principal components) has more than two zero crossings. Implications of these theorems for color technology and robotic vision are noted.
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Kim, Hongsuk H. "Critical Reflectance." In Optical Remote Sensing of the Atmosphere. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/orsa.1990.wd15.

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In previous works, a model which relates intensities to ground reflectance and aerosol scattering phase function was introduced as it is stored in the form of a simplified 3 by 3 matrix 1). And in a subsequent study, several atmospheres, in a range of optical thicknesses, were applied in search of a best fit model for a Landsat scene 2). In this paper, further refinement of the methodology to infer an optical thickness parameter, τ(Mie), by the use of "the critical reflectance " is discussed.
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Knill, David C., and Daniel Kersten. "Cooperativity in the perception of surface shape and reflectance." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.mjj1.

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The luminance pattern in an image is a function of several different scene characteristics. The primary ones are surface shape, surface reflectance, and the pattern of incident illumination. Faced with the task of generating and maintaining an accurate percept of these scene characteristics, our visual systems must somehow be able to parcel out the different causes to changes in image luminance. This requires some degree of interaction in the estimation of shape, reflectance, and illumination. We used two juxtaposed, equivalent luminance gradients as a stimulus for studying this interaction. When the stimulus appears flat, the perceived lightness of the two patterns is consistent with the assumption of a smooth illuminant over a step change in reflectance. This is not, however, the only plausible percept, as a similar luminance pattern can be generated by natural shading of two smoothly curved surfaces with equivalent reflectances. We added several different shape cues to the stimulus in support of the latter interpretation, including occluding contours, texture, and stereo, and studied their effect on perceived lightness.
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Tominaga, Shoji, and Brian A. Wandell. "Estimation of Surface Spectral Reflectance on the Standard Model." In Image Understanding and Machine Vision. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/iumv.1989.mb2.

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The standard reflectance model for inhomogeneous materials suggests that to a good approximation the reflectance function can be described as the weighted sum of two functions1,2. One function represents the interface (specular) reflection, and the second function represents the subsurface (diffuse) reflection. Let S I (λ) and S S (λ) be the surface spectral reflectances for the two components of interface and subsurface reflections, and let E(λ) be the spectral power distribution of the incident light. Then reflected light is where c I (θ) and c S (θ) are the geometric scale factors. The parameters θ vary with the viewing geometry. In a previous paper2 we have evaluated this model and shown how to use light reflected from pairs of surfaces to estimate the spectral power distribution of the illuminant.
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Messerschmidt, Robert G. "Toward Quantitative Diffuse Reflectance: Diffuse Reflectance Without Specular Impurity." In 1985 International Conference on Fourier and Computerized Infrared Spectroscopy, edited by David G. Cameron and Jeannette G. Grasselli. SPIE, 1985. http://dx.doi.org/10.1117/12.970798.

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Reports on the topic "Reflectance"

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Barnes, P. Yvonne, Edward A. Early, and Albert C. Parr. Spectral reflectance. Gaithersburg, MD: National Institute of Standards and Technology, 1998. http://dx.doi.org/10.6028/nist.sp.250-48.

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Weidner, Victor R., and Jack J. Hsia. Spectral reflectance. Gaithersburg, MD: National Bureau of Standards, 1987. http://dx.doi.org/10.6028/nbs.sp.250-8.

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Leblanc, S. G., J. M. Chen, H. P. White, R. Latifovic, R. Fernandes, J. L. Roujean, and R. Lacaze. Mapping leaf area index heterogeneity over Canada using directional reflectance and anisotropy canopy reflectance models using directional reflectance and anisotropy canopy reflectance models. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2002. http://dx.doi.org/10.4095/219874.

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Alchanatis, Victor, Stephen W. Searcy, Moshe Meron, W. Lee, G. Y. Li, and A. Ben Porath. Prediction of Nitrogen Stress Using Reflectance Techniques. United States Department of Agriculture, November 2001. http://dx.doi.org/10.32747/2001.7580664.bard.

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Commercial agriculture has come under increasing pressure to reduce nitrogen fertilizer inputs in order to minimize potential nonpoint source pollution of ground and surface waters. This has resulted in increased interest in site specific fertilizer management. One way to solve pollution problems would be to determine crop nutrient needs in real time, using remote detection, and regulating fertilizer dispensed by an applicator. By detecting actual plant needs, only the additional nitrogen necessary to optimize production would be supplied. This research aimed to develop techniques for real time assessment of nitrogen status of corn using a mobile sensor with the potential to regulate nitrogen application based on data from that sensor. Specifically, the research first attempted to determine the system parameters necessary to optimize reflectance spectra of corn plants as a function of growth stage, chlorophyll and nitrogen status. In addition to that, an adaptable, multispectral sensor and the signal processing algorithm to provide real time, in-field assessment of corn nitrogen status was developed. Spectral characteristics of corn leaves reflectance were investigated in order to estimate the nitrogen status of the plants, using a commercial laboratory spectrometer. Statistical models relating leaf N and reflectance spectra were developed for both greenhouse and field plots. A basis was established for assessing nitrogen status using spectral reflectance from plant canopies. The combined effect of variety and N treatment was studied by measuring the reflectance of three varieties of different leaf characteristic color and five different N treatments. The variety effect on the reflectance at 552 nm was not significant (a = 0.01), while canonical discriminant analysis showed promising results for distinguishing different variety and N treatment, using spectral reflectance. Ambient illumination was found inappropriate for reliable, one-beam spectral reflectance measurement of the plants canopy due to the strong spectral lines of sunlight. Therefore, artificial light was consequently used. For in-field N status measurement, a dark chamber was constructed, to include the sensor, along with artificial illumination. Two different approaches were tested (i) use of spatially scattered artificial light, and (ii) use of collimated artificial light beam. It was found that the collimated beam along with a proper design of the sensor-beam geometry yielded the best results in terms of reducing the noise due to variable background, and maintaining the same distance from the sensor to the sample point of the canopy. A multispectral sensor assembly, based on a linear variable filter was designed, constructed and tested. The sensor assembly combined two sensors to cover the range of 400 to 1100 nm, a mounting frame, and a field data acquisition system. Using the mobile dark chamber and the developed sensor, as well as an off-the-shelf sensor, in- field nitrogen status of the plants canopy was measured. Statistical analysis of the acquired in-field data showed that the nitrogen status of the com leaves can be predicted with a SEP (Standard Error of Prediction) of 0.27%. The stage of maturity of the crop affected the relationship between the reflectance spectrum and the nitrogen status of the leaves. Specifically, the best prediction results were obtained when a separate model was used for each maturity stage. In-field assessment of the nitrogen status of corn leaves was successfully carried out by non contact measurement of the reflectance spectrum. This technology is now mature to be incorporated in field implements for on-line control of fertilizer application.
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Barron, Jonathan, and Jitendra Malik. Shape, Illumination, and Reflectance from Shading. Fort Belvoir, VA: Defense Technical Information Center, May 2013. http://dx.doi.org/10.21236/ada586648.

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Veloso, Rita Carvalho, Catarina Dias, Andrea Resende Souza, Joana Maia, Nuno M. M. Ramos, and João Ventura. Improving the optical properties of finishing coatings for façade systems. Department of the Built Environment, 2023. http://dx.doi.org/10.54337/aau541592743.

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The need to improve energy efficiency of the building stock has led to a continuous increase in the implementation of exterior thermal insulation systems, such as ETICS. Progressively, these systems are being applied with darker colours, increasing the concern for hygrothermal behaviour and durability. Despite the significant developed studies, very few reports regarding their optical properties are available. The optical and catalytic capacity turns nanomaterials into excellent candidates for use in finishing coatings with high solar reflectance with dark colours without affecting the aesthetic characteristics, thus improving the durability of such coatings. Our study targeted the development of innovative envelope systems by increasing their solar reflectance through new finishing coatings formulations with the inclusion of nanoparticles. For that, it is necessary to develop and optimize nanoparticles formulations to achieve a high near-infrared reflectance. Here, we studied how the incorporation of reflective nanomaterials influence the optical behaviour of a black colourant for a finishing coating, varying the concentration in the coating from 0 to 20%. Such optical performance was experimentally evaluated through spectral reflectance calculations using a modular spectrophotometer, which allowed an understanding of the relation between these properties and the morphological and structural characteristics of the nanoparticles. The results from such studies can help formulate new finishing coatings with increased near-infrared reflectance of buildings façades, using, for instance, more than one type of nanoparticle.
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Ramos, Nuno M. M., Joana Maia, Rita Carvalho Veloso, Andrea Resende Souza, Catarina Dias, and João Ventura. Envelope systems with high solar reflectance by the inclusion of nanoparticles – an overview of the EnReflect Project. Department of the Built Environment, 2023. http://dx.doi.org/10.54337/aau541621982.

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High reflectance materials constitute an attractive idea to reduce cooling loads, which is crucial for attaining the Nearly Zero Energy Buildings goal, also presenting the benefit of broadening the range of colours applicable in building facades. The EnReflect project intended to re-design envelope systems by increasing their solar reflectance through nanotechnology. The main idea was to produce novel nanomaterial-based coatings with high near-infrared (NIR) reflectance by tuning their optical properties and testing their compatibility with typical insulation technologies such as ETICS. As such, this project focused on the synthesis of nanoparticles with improved NIR reflectance, the evaluation of the hygrothermal-mechanical behaviour of thermal insulation systems with the application of the improved coating solutions, the characterization of the more relevant material properties and the durability assessment. One of the main achievements was the development of a facile synthesis of a nanocomposite with improved performance in the NIR region that allowed the reflectance improvement of a dark-finishing coating. Also, the incorporation of such nanoparticles had a positive effect on keeping their optical properties after accelerated ageing cycles. The development of numerical simulations allowed the estimation of the maximum surface temperature in Mediterranean climates under different optical parameters. The study of the hygrothermal behaviour of thermal enhanced façades led to the development of a new durability assessment methodology which contributed to closing a standardization gap.
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Letcher, Theodore, Julie Parno, Zoe Courville, Lauren Farnsworth, and Jason Olivier. A generalized photon-tracking approach to simulate spectral snow albedo and transmittance using X-ray microtomography and geometric optics. Engineer Research and Development Center (U.S.), June 2023. http://dx.doi.org/10.21079/11681/47122.

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A majority of snow radiative transfer models (RTMs) treat snow as a collection of idealized grains rather than an organized ice–air matrix. Here we present a generalized multi-layer photon-tracking RTM that simulates light reflectance and transmittance of snow based on X-ray micro- tomography images, treating snow as a coherent 3D structure rather than a collection of grains. The model uses a blended approach to expand ray-tracing techniques applied to sub-1 cm3 snow samples to snowpacks of arbitrary depths. While this framework has many potential applications, this study’s effort is focused on simulating reflectance and transmittance in the visible and near infrared (NIR) through thin snow- packs as this is relevant for surface energy balance and remote sensing applications. We demonstrate that this framework fits well within the context of previous work and capably reproduces many known optical properties of a snow surface, including the dependence of spectral reflectance on the snow specific surface area and incident zenith angle as well as the surface bidirectional reflectance distribution function (BRDF). To evaluate the model, we compare it against reflectance data collected with a spectroradiometer at a field site in east-central Vermont. In this experiment, painted panels were inserted at various depths beneath the snow to emulate thin snow. The model compares remarkably well against the reflectance measured with a spectroradiometer, with an average RMSE of 0.03 in the 400–1600 nm range. Sensitivity simulations using this model indicate that snow transmittance is greatest in the visible wavelengths, limiting light penetration to the top 6 cm of the snowpack for fine-grain snow but increasing to 12 cm for coarse-grain snow. These results suggest that the 5% transmission depth in snow can vary by over 6 cm according to the snow type.
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B. R. Marshall. Glue Film Thickness Measurements by Spectral Reflectance. Office of Scientific and Technical Information (OSTI), September 2010. http://dx.doi.org/10.2172/991875.

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Fox, Jay A., and Cynthia R. Gautier. Model Tank Reflectance Study at Two Wavelengths. Fort Belvoir, VA: Defense Technical Information Center, June 1990. http://dx.doi.org/10.21236/ada225468.

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