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Adachi, Yusuke, Ryota Kikuchi, Kenta Obata i Hiroki Yoshioka. "Relative Azimuthal-Angle Matching (RAM): A Screening Method for GEO-LEO Reflectance Comparison in Middle Latitude Forests". Remote Sensing 11, nr 9 (8.05.2019): 1095. http://dx.doi.org/10.3390/rs11091095.
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This study introduced a data screening method for comparing the reflectances in middle latitude forest regions collected by a Geostationary Earth Observing (GEO) satellite and a Low Earth Orbit (LEO) satellite. This method attempts to reduce the differences between the relative azimuth angles of the GEO and LEO observations. The method, called relative azimuthal-angle matching (RAM), takes advantage of the high temporal resolution of the GEO satellites, which enables collection of a wide range of relative azimuth angles within a day. The performance of the RAM method was evaluated using data in the visible and near-infrared bands collected by the Himawari-8/Advanced Himawari Imager (AHI) and the Terra/Moderate Resolution Imaging Spectroradiometer (MODIS). The consistency of the reflectance pairs of MODIS and AHI selected by the RAM method was compared with the consistency of the reflectance pairs acquired simultaneously by the two sensors. The data were matched pixel-by-pixel after applying atmospheric corrections and cloud screening. The results show that RAM improved the reflectance ratio by approximately 10% for the red and NIR bands on average relative to the simultaneous observations. Significant improvements in the two bands were observed (20%), especially among data collected in the fall and winter. Performance of RAM depends largely on season. Especially in summer, the reflectance pair chosen by RAM showed less consistency than solar zenith-angle matching (SZM). The results also indicated the relatively large influence of the spectral response functions on the green and red bands of the two sensors.
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Hamilton, Paul, Brian Sullivan i Diann Gaalema. "Short-term changes in dorsal reflectance for background matching in Ornate Tree Lizards (Urosaurus ornatus)". Amphibia-Reptilia 29, nr 4 (2008): 473–77. http://dx.doi.org/10.1163/156853808786230488.
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AbstractSome lizards are thought to exhibit short-term changes in color to match their background, but this ability has not been verified empirically. We tested the hypothesis that lizards will change dorsal reflectance over a series of days to match their backgrounds. We housed male and female Ornate Tree Lizards (Urosaurus ornatus) for five days in aquaria painted to match environmental extremes in substrate reflectance. Standardized photographs were taken each day yielding dorsal percent reflectance values. After the first day, reflectance of lizards changed significantly to more closely match their backgrounds; this effect became more pronounced through the fifth and final day of the experiment.
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Romney, A. K., i T. Indow. "Estimating physical reflectance spectra from human color-matching experiments". Proceedings of the National Academy of Sciences 99, nr 22 (18.10.2002): 14607–10. http://dx.doi.org/10.1073/pnas.222558899.
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Lundgaard, Stefan, Soon Hock Ng, Yoshiaki Nishijima, Michael Mazilu i Saulius Juodkazis. "Black Metals: Optical Absorbers". Micromachines 11, nr 3 (28.02.2020): 256. http://dx.doi.org/10.3390/mi11030256.
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We demonstrate a concept and fabrication of lithography-free layered metal-SiO2 thin-film structures which have reduced reflectivity (black appearance), to as low as 0.9%, with 4.9% broadband reflectance (8.9% for soda lime) in the 500–1400 nm range. The multi-layered (four layers) thin-film metamaterial is designed so that optical impedance matching produces minimal reflectance and transmittance within the visible and infra-red (IR) spectral region for a range of incident angles. The structure has enhanced absorbance and is easily tuned for reduced minimal transmission and reflection. This approach should allow for novel anti-reflection surfaces by impedance matching to be realized.
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Mishra, V. D., J. K. Sharma i R. Khanna. "Review of topographic analysis methods for the western Himalaya using AWiFS and MODIS satellite imagery". Annals of Glaciology 51, nr 54 (2010): 153–60. http://dx.doi.org/10.3189/172756410791386526.
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AbstractThe topographic effects of differential terrain illumination in optical satellite imagery of rugged mountainous regions have serious consequences for qualitative and quantitative analysis for various snow applications. Therefore, effective removal or minimization of topographic effects is necessary in satellite image data of mountainous regions. Different methods for topographic corrections, including C-correction, Minnaert corrections (including slope) and slope-matching method, are analysed in the context of snow reflectance. Combination of dark-object subtraction models DOS1 and DOS3 is used for image-based atmospheric corrections while considering the effect of Rayleigh scattering on the transmissivity in different spectral bands of AWiFS and MODIS image data. The performance of different models is evaluated using (1) visual analysis, (2) change in snow reflectance on sunny and shady slopes after the corrections, (3) validation with in situ observations and (4) graphical analysis. The results show that the slope-matching technique could eliminate most of the shadowing effects in Himalayan rugged terrain and correctly estimate snow reflectance from AWiFS and MODIS imagery. The validation of results with in situ observations for both types of imagery suggests that all other methods significantly underestimate reflectance values after the corrections.
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Churmakov, D. Y., I. V. Meglinski i D. A. Greenhalgh. "Influence of refractive index matching on the photon diffuse reflectance". Physics in Medicine and Biology 47, nr 23 (20.11.2002): 4271–85. http://dx.doi.org/10.1088/0031-9155/47/23/312.
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Li, Shande, Xiaoxun Wu, Jinxiu Duan, Shuai Yuan, Cun Wang, Yane Ma i Zhifu Zhang. "A Composite Matching Layer with Anti-Reflection Characteristics for Broadband Acoustic Scattering Reduction". Shock and Vibration 2021 (15.12.2021): 1–10. http://dx.doi.org/10.1155/2021/1480264.
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A composite matching layer composed of periodically arranged scatters with anti-reflection (AR) characteristics is proposed for broadband scattering reduction. The anti-reflection structure is composed of periodically arranged metal foam scatters, and it is the first attempt to be applied in the field of suppressing acoustic reflection. A complete theoretical model is developed to reveal the mechanism of scattering reduction and acoustic absorption based on effective medium theory and the transfer matrix method. The correctness and effectiveness of the theoretical model are verified by the finite element method (FEM), showing acoustic reflectance of less than 13.5% at broadband frequencies. The variation trends of reflectance are deeply investigated. The superior acoustic scattering reduction performance suggests that the matching layer possesses potential for acoustic imaging equipment and acoustic stealth.
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LEE, MAL-REY, i TAE-EUN KIM. "ESTIMATION OF HYBRID REFLECTANCE PROPERTIES AND SHAPE RECONSTRUCTION USING THE LMS METHOD". International Journal on Artificial Intelligence Tools 08, nr 01 (marzec 1999): 1–17. http://dx.doi.org/10.1142/s0218213099000026.
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This paper presents a new method to estimate reflectance properties of non–Lambertian surface by the least-mean-square (LMS) algorithm. In this paper, hybrid reflectance of an object is represented by the Torrance–Sparrow model. We determine reflectance parameters which minimize the sum squared difference of the intensity distribution between the image of a sample sphere and the calculated image. The estimated reflectance parameters provide the range data with intensity distributions. Therefore, we generate three reference images of a range sphere, which has the same diameter as that of the sample, from the same viewpoint with different light directions. Direct matching of the object images to the references can precisely reconstruct the shape of the object. This paper uses a plate diffuse illumination to alleviate the effects of specular spike and highlights. The simulation results show that the proposed method can estimate reflectance properties of the hybrid surface, and also recover the object shape.
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LEE, MAL-REY. "3D SHAPE RECONSTRUCTION OF HYBRID REFLECTANCE USING THE LMS ALGORITHM". International Journal of Pattern Recognition and Artificial Intelligence 15, nr 04 (czerwiec 2001): 723–34. http://dx.doi.org/10.1142/s0218001401001040.
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In this paper, we present a new approach for determining the reflectance properties of surface and recovering 3D shapes from intensity images. We determine reflectance parameters which minimize the sum squared difference of the intensity distribution between the image of a sample sphere and the calculated image. The estimated reflectance parameters provide the range data with intensity distributions. Therefore, we generate three reference images of a range sphere, which has the same diameter as that of the sample, from the same viewpoint but with different light directions. Direct matching of the object images to the references can precisely reconstruct the shape of the object. This paper uses a plate diffuse illumination to alleviate the effects of specular spike and highlights. The simulation results show that the proposed method can estimate reflectance properties of the hybrid surface, and also recover the object shape.
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Luo, Lin, Hui-Liang Shen, Si-Jie Shao i John Xin. "Empirical model for matching spectrophotometric reflectance of yarn windings and multispectral imaging reflectance of single strands of yarns". Journal of the Optical Society of America A 32, nr 8 (10.07.2015): 1459. http://dx.doi.org/10.1364/josaa.32.001459.
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Charrois, Luc, Emmanuel Cosme, Marie Dumont, Matthieu Lafaysse, Samuel Morin, Quentin Libois i Ghislain Picard. "On the assimilation of optical reflectances and snow depth observations into a detailed snowpack model". Cryosphere 10, nr 3 (13.05.2016): 1021–38. http://dx.doi.org/10.5194/tc-10-1021-2016.
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Abstract. This paper examines the ability of optical reflectance data assimilation to improve snow depth and snow water equivalent simulations from a chain of models with the SAFRAN meteorological model driving the detailed multilayer snowpack model Crocus now including a two-stream radiative transfer model for snow, TARTES. The direct use of reflectance data, allowed by TARTES, instead of higher level snow products, mitigates uncertainties due to commonly used retrieval algorithms.Data assimilation is performed with an ensemble-based method, the Sequential Importance Resampling Particle filter, to represent simulation uncertainties. In snowpack modeling, uncertainties of simulations are primarily assigned to meteorological forcings. Here, a method of stochastic perturbation based on an autoregressive model is implemented to explicitly simulate the consequences of these uncertainties on the snowpack estimates.Through twin experiments, the assimilation of synthetic spectral reflectances matching the MODerate resolution Imaging Spectroradiometer (MODIS) spectral bands is examined over five seasons at the Col du Lautaret, located in the French Alps. Overall, the assimilation of MODIS-like data reduces by 45 % the root mean square errors (RMSE) on snow depth and snow water equivalent. At this study site, the lack of MODIS data on cloudy days does not affect the assimilation performance significantly. The combined assimilation of MODIS-like reflectances and a few snow depth measurements throughout the 2010/2011 season further reduces RMSEs by roughly 70 %. This work suggests that the assimilation of optical reflectances has the potential to become an essential component of spatialized snowpack simulation and forecast systems. The assimilation of real MODIS data will be investigated in future works.
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Swatland, H. J. "Optical properties of turkey pectoralis muscle affecting detection of connective tissue fluorescence". Canadian Journal of Animal Science 81, nr 1 (1.03.2001): 25–31. http://dx.doi.org/10.4141/a00-053.
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A dual-channel probe was used to detect fluorescence (excitation 365 nm, emission 400 to 550 nm) and reflectance (550 nm) in turkey pectoralis muscles (n= 157). All fluorescence peaks had matching reflectance peaks, but not vice versa. Thus, some reflectance peaks originated from non-fluorescent structures in the muscle. Electrical impedance was used to assess fluid distribution. Electrical capacitance was correlated (P< 0.01) with areas under probe signals (r= 0.19 for both fluorescence and reflectance). In a subset of samples (n= 45), the reflectance of initially polarized light was used to assess light scattering. Consistent relationships between probe signals and the reflectance of initially polarized light were detected. When polarized light was parallel with the longitudinal axes of muscle fibers, and when the analyzer was parallel with the polarizer, reflectance was correlated (P< 0.01) with the incidence of fluorescence and reflectance peaks (R= 0.58 and R= 0.59, respectively), with mean peak intensity (R= 0.51 and R= 0.49, respectively), and with mean half-peak width (R= 0.48 and R= 0.56, respectively). The spectral distribution of correlations indicated that myoglobin as well as differences in light scattering affected the probe detection of connective tissue fluorescence. Thus, bulk optical properties of muscle affected probe detection of connective tissue fluorescence. Key words: Connective tissue, fluorescence, turkey meat
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Chen, Fei, Di Wu, Rafiqul Islam, Yu Toida, Chiharu Kawamoto, Monica Yamauti i Hidehiko Sano. "Evaluation of Color and Spectral Behavior of a Novel Flowable Resin Composite after Water Aging: An In Vitro Study". Materials 15, nr 12 (9.06.2022): 4102. http://dx.doi.org/10.3390/ma15124102.
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Background: This study aimed to evaluate the color matching, light transmittance, and reflectance characteristics of the novel flowable resin composite OCF-001 (OCF). Methods: Fifty-four resin composite molds were made with simulated class I cavities of A2, A3, and A4 shades by filling the rubber mold interspace with Estelite Sigma Quick (ESQ), Gracefil Putty (GP) and Filtek Supremme Ultra (FSU). After applying the adhesive, three different flowable resin composites (n = 6), OCF, Gracefil LoFlo (GLF), and Supreme Ultra Flowable (SUF), were used to fill the cavities. A colorimeter was used to measure the color parameters (CIEDE2000). The color measurements were taken immediately and after 28 days. Data were analyzed using the nonparametric Kruskal–Wallis (α = 0.05) and Wilcoxon tests. The light transmittance and reflection characteristics were measured with a black background using a spectrophotometer under D65 illumination. Results: The ΔE00, and ΔC of OCF was lower than other tested materials in A2 and A3 shades both immediately and after 28 days. OCF showed the highest transmittance characteristic, and a relatively stable reflectance curve in all the wavelengths. Conclusions: OCF showed better shade matching with the surrounding shades of A2 and A3, a relative uniform reflectance and higher light transmission properties.
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Cho, Youngsoo, i Guneik Jang. "Pattern Visibility Enhancement by the Hybrimer Index-Matching Inter Layer in Oxide/Metal/Oxide-Structured Transparent Conductive Electrode on Flexible Polyethylene Terephthalate Substrates". Journal of Nanoscience and Nanotechnology 21, nr 3 (1.03.2021): 1932–36. http://dx.doi.org/10.1166/jnn.2021.18918.
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For this study, we fabricated transparent Mn-doped tin oxide (MTO)/Ag/MTO films with refractive index-matching layer on a polyethylene terephthalate (PET) substrate. The hybrimer indexmatching layer containing TIP (Titanium isopropoxide) in hydroxy terminated PDMS (PDMS-OH) matrix was placed between the MTO/Ag/MTO multilayer and PET substrate. MTO and Ag were deposited by using RF/DC magnetron sputtering at room temperature, whereas a hybrimer mixture was spin-coated on the PET substrate after adjusting the molar ratios between the TIP and PDMS-OH. Pattern visibility was examined by comparing the differences in the reflectance and transmittance of MTO/Ag/MTO multilayer films before and after placing the hybrimer index-matching layer. As the PDMS-OH concentration increased, the reflectance difference at the wavelength of 550 nm (ΔR550nm) showed a tendency of decreasing from 0.66% to 0.53%. The index-matched MTO/Ag/MTO multilayer films showed the highest transmittance (>86% at 550 nm) at a molar ratio of 1:4.
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Köprü, Ramazan, Sedat Kilinç, Çağatay Aydin, Doğu Çağdaş Atilla, Cahit Karakuş i Binboğa Siddik Yarman. "Ultra wideband matching network design for a V-shaped square planar monopole antenna". International Journal of Microwave and Wireless Technologies 6, nr 6 (13.08.2014): 555–64. http://dx.doi.org/10.1017/s1759078714001081.
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In this paper, design, manufacture, and measurement of a wideband matching network for a broadband V-shaped square planar monopole antenna (V-SPMA) is presented. Matching network design is unavoidable in most cases even vital to facilitate a maximally flat power transfer gain for an antenna. In the work, a bandpass matching network (BPMN) design is done for a particular square monopole antenna with V-shaped coupling element that has essentially bandwidth increasing effect. Designed BPMN and the antenna forms a VSPMA–BPMN matched antenna structure. “real frequency technique” is employed in the BPMN design. BPMN prototype circuit has been constructed on an FR4 laminate with commercial microwave chip inductors and capacitors. Vector network analyzer gain and reflectance measurements of the matched antenna structure have shown highly compatible results to those of the theoretical design simulations along the passband (~0.8–4.7 GHz). Furthermore, newly proposed distributed capacitor–resistor lossy model for microstrip lines used in the BPMN circuit have exhibited that it can successfully mimic the measured gain and reflectance performance of the matched structure in passband and even in stopband upto 8 GHz. Designed structure can be utilized as a one single wideband broadcasting medium suitable for many communication standards such as GSM, 3G, and Wi-Fi.
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Gao, Bo-Cai, i Rong-Rong Li. "Improving Water Leaving Reflectance Retrievals from ABI and AHI Data Acquired Over Case 2 Waters from Present Geostationary Weather Satellite Platforms". Remote Sensing 12, nr 19 (7.10.2020): 3257. http://dx.doi.org/10.3390/rs12193257.
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The current generation of geostationary weather satellite instruments, such as the Advanced Baseline Imagers (ABIs) on board the US NOAA GOES 16 and 17 satellites and the Advanced Himawari Imagers (AHIs) on board the Japanese Himawari-8/9 satellites, have six channels located in the visible to shortwave IR (SWIR) spectral range. These instruments can acquire images over both land and water surfaces at spatial resolutions between 0.5 and 2 km and with a repeating cycle between 5 and 30 min depending on the mode of operation. The imaging data from these instruments have clearly demonstrated the capability in detecting sediment movements over coastal waters and major chlorophyll blooms over deeper oceans. At present, no operational ocean color data products have been produced from ABI data. Ocean color data products have been operationally generated from AHI data at the Japan Space Agency, but the spatial coverage of the products over very turbid coastal waters are sometimes lacking. In this article, we describe atmospheric correction algorithms for retrieving water leaving reflectances from ABI and AHI data using spectrum-matching techniques. In order to estimate aerosol models and optical depths, we match simultaneously the satellite-measured top of atmosphere (TOA) reflectances on the pixel by pixel basis for three channels centered near 0.86, 1.61, and 2.25 μm (or any combinations of two channels among the three channels) with theoretically simulated TOA reflectances. We demonstrate that water leaving reflectance retrievals can be made from ABI and AHI data with our algorithms over turbid case two waters. Our spectrum-matching algorithms, if implemented onto operational computing facilities, can be complimentary to present operational ocean versions of atmospheric correction algorithms that are mostly developed based on the SeaWiFS type of two-band ratio algorithm.
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Fukue, Kiyonari, i Haruhisa Shimoda. "GLOBAL LAND COVER CLASSIFICATION USING MODIS SURFACE REFLECTANCE PROSUCTS". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B7 (21.06.2016): 219–22. http://dx.doi.org/10.5194/isprs-archives-xli-b7-219-2016.
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The objective of this study is to develop high accuracy land cover classification algorithm for Global scale by using multi-temporal MODIS land reflectance products. In this study, time-domain co-occurrence matrix was introduced as a classification feature which provides time-series signature of land covers. Further, the non-parametric minimum distance classifier was introduced for timedomain co-occurrence matrix, which performs multi-dimensional pattern matching for time-domain co-occurrence matrices of a classification target pixel and each classification classes. The global land cover classification experiments have been conducted by applying the proposed classification method using 46 multi-temporal(in one year) SR(Surface Reflectance) and NBAR(Nadir BRDF-Adjusted Reflectance) products, respectively. IGBP 17 land cover categories were used in our classification experiments. As the results, SR and NBAR products showed similar classification accuracy of 99%.
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Fukue, Kiyonari, i Haruhisa Shimoda. "GLOBAL LAND COVER CLASSIFICATION USING MODIS SURFACE REFLECTANCE PROSUCTS". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B7 (21.06.2016): 219–22. http://dx.doi.org/10.5194/isprsarchives-xli-b7-219-2016.
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The objective of this study is to develop high accuracy land cover classification algorithm for Global scale by using multi-temporal MODIS land reflectance products. In this study, time-domain co-occurrence matrix was introduced as a classification feature which provides time-series signature of land covers. Further, the non-parametric minimum distance classifier was introduced for timedomain co-occurrence matrix, which performs multi-dimensional pattern matching for time-domain co-occurrence matrices of a classification target pixel and each classification classes. The global land cover classification experiments have been conducted by applying the proposed classification method using 46 multi-temporal(in one year) SR(Surface Reflectance) and NBAR(Nadir BRDF-Adjusted Reflectance) products, respectively. IGBP 17 land cover categories were used in our classification experiments. As the results, SR and NBAR products showed similar classification accuracy of 99%.
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Bernard, E., C. Moulin, D. Ramon, D. Jolivet, J. Riedi i J. M. Nicolas. "Validation of an AOT product over land at the 0.6 μm channel of the SEVIRI sensor onboard MSG". Atmospheric Measurement Techniques Discussions 4, nr 3 (24.05.2011): 3147–98. http://dx.doi.org/10.5194/amtd-4-3147-2011.
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Abstract. The Spinning Enhanced Visible and InfraRed Imager (SEVIRI) aboard Meteosat Second Generation (MSG) launched in 2003 by EUMETSAT is dedicated to the Nowcasting applications and Numerical Weather Prediction and to provide information for climate monitoring and research. We use the data in visible and near infrared channels to derive the Aerosol Optical Thickness (AOT) over land. The algorithm is based on the assumption that the Top Of the Atmosphere (TOA) reflectance increases with the aerosol load. This is a reasonable assumption except in case of absorbing aerosols above bright surfaces. We assume that the minimum in a 14-day time series of the TOA reflectance is, once corrected from gaseous scattering and absorption, representative of the surface reflectance. The AOT and the aerosol model (a set of 5 models are used), are retrieved by matching the simulated TOA reflectance with the TOA reflectances measured by SEVIRI in its visible and Near Infra-Red (NIR) spectral bands. The high temporal resolution of the data acquisition by SEVIRI allows to retrieve the AOT every 15 min with a spatial resolution of 3km at sub-satellite point, over the whole SEVIRI disk which covers Europe, Africa and part of South America. The resulting AOT, a Level 2 product at the same temporal and spatial resolution than SEVIRI, is presented and evaluated in this paper. The AOT has been validated using ground based measurements from AERONET, a sun-photometer network, focusing over Europe for 3 months in 2006. The SEVIRI estimates correlate well with the AERONET measurements, r = 0.64, with a slight underestimate, bias = −0.017. The sources of errors are mainly the cloud contamination and the bad estimation of the surface reflectance. The temporal evolutions exhibited by both dataset show very good agreement which allows to conclude that the AOT Level 2 product from SEVIRI can be used to quantify the aerosol content and to monitor its daily evolution with a high temporal frequency. The comparison with daily maps of MODIS AOT level 3 product shows qualitative good agreements in the retrieved geographic patterns of AOT. Given the high spatial and temporal resolutions obtained with this approach, our results have clear potential for applications ranging from air quality monitoring to climate studies.
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Liu, Zhao Yan, Ling Ling Ma, Ling Li Tang i Yong Gang Qian. "LAI Retrieval Based on PROSPECT-SAILH Model from Multi-Angular Data of WiDAS Imaging System". Advanced Materials Research 518-523 (maj 2012): 5697–703. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.5697.
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The aim of this study is to assess the capability of estimating Leaf Area Index (LAI) from high spatial resolution multi-angular Vis-NIR remote sensing data of WiDAS (Wide-Angle Infrared Dual-mode Line/Area Array Scanner) imaging system by inverting the coupled radiative transfer models PROSPECT-SAILH. Based on simulations from SAILH canopy reflectance model and PROSPECT leaf optical properties model, a Look-up Table (LUT) which describes the relationship between multi-angular canopy reflectance and LAI has been produced. Then the LAI can be retrieved from LUT by directly matching canopy reflectance of six view directions and four spectral bands with LAI. The inversion results are validated by field data, and by comparing the retrieval results of single-angular remote sensing data with multi-angular remote sensing data, we can found that the view angle takes the obvious impact on the LAI retrieval of single-angular data and that high accurate LAI can be obtained from the high resolution multi-angular remote sensing technology.
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Wu, Shiyong, Ruofei Zhong, Qingyang Li, Ke Qiao i Qing Zhu. "An Interband Registration Method for Hyperspectral Images Based on Adaptive Iterative Clustering". Remote Sensing 13, nr 8 (13.04.2021): 1491. http://dx.doi.org/10.3390/rs13081491.
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In the context of the problem of image blur and nonlinear reflectance difference between bands in the registration of hyperspectral images, the conventional method has a large registration error and is even unable to complete the registration. This paper proposes a robust and efficient registration algorithm based on iterative clustering for interband registration of hyperspectral images. The algorithm starts by extracting feature points using the scale-invariant feature transform (SIFT) to achieve initial putative matching. Subsequently, feature matching is performed using four-dimensional descriptors based on the geometric, radiometric, and feature properties of the data. An efficient iterative clustering method is proposed to perform cluster analysis on the proposed descriptors and extract the correct matching points. In addition, we use an adaptive strategy to analyze the key parameters and extract values automatically during the iterative process. We designed four experiments to prove that our method solves the problem of blurred image registration and multi-modal registration of hyperspectral images. It has high robustness to multiple scenes, multiple satellites, and multiple transformations, and it is better than other similar feature matching algorithms.
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Tang, Tianyu, Yanlin Tang i Xiaonan Wei. "Analysis on Spectral Matching of Biochemical Component for Rice". Journal of Physics: Conference Series 2112, nr 1 (1.11.2021): 012028. http://dx.doi.org/10.1088/1742-6596/2112/1/012028.
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Abstract The protein, starch and amylose are three important indexes to characterize rice quality. The starch, crude protein and amylose of rice were extracted by experiments. The hyperspectral reflectance of starch, crude protein and amylose, their mixed samples and rice samples were determined by a ASD FieldSpec Pro FR™ The spectral characteristics of starch, crude protein, amylose and their correlation with component content were analyzed by using spectral matching technique and multivariate statistical method. The results showed that the spectra of three biochemical components were significantly different, and the spectral peaks and valleys of the mixed samples showed “red shift” or “blue shift”. The contents (%) of crude protein, starch and amylose in rice flour were significantly related to the absorption area S between 2020nm and 2235nm on their spectral curve. The results showed that the hyperspectral method could be used to estimate the contents of crude protein, starch and amylose content in rice, and then to detect rice quality.
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Cherry, Michael I., i T. D. Bennett. "Egg colour matching in an African cuckoo, as revealed by ultraviolet-visible reflectance spectrophotometry". Proceedings of the Royal Society of London. Series B: Biological Sciences 268, nr 1467 (22.03.2001): 565–71. http://dx.doi.org/10.1098/rspb.2000.1414.
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Leihong, Zhang, Liang Dong, Zhang Dawei, Gao Xiumin i Ma Xiuhua. "Study of Spectral Reflectance Reconstruction Based on an Algorithm for Improved Orthogonal Matching Pursuit". Journal of the Optical Society of Korea 20, nr 4 (25.08.2016): 515–23. http://dx.doi.org/10.3807/josk.2016.20.4.515.
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Tan, Jing, Robert Frouin, Didier Ramon i François Steinmetz. "On the Adequacy of Representing Water Reflectance by Semi-Analytical Models in Ocean Color Remote Sensing". Remote Sensing 11, nr 23 (28.11.2019): 2820. http://dx.doi.org/10.3390/rs11232820.
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Deterministic or statistical inversion schemes to retrieve ocean color from space often use a simplified water reflectance model that may introduce unrealistic constraints on the solution, a disadvantage compared with standard, two-step algorithms that make minimal assumptions about the water signal. In view of this, the semi-analytical models of Morel and Maritorena (2001), MM01, and Park and Ruddick (2005), PR05, used in the spectral matching POLYMER algorithm (Steinmetz et al., 2011), are examined in terms of their ability to restitute properly, i.e., with sufficient accuracy, water reflectance. The approach is to infer water reflectance at MODIS wavelengths, as in POLYMER, from theoretical simulations (using Hydrolight with fluorescence and Raman scattering) and, separately, from measurements (AERONET-OC network). A wide range of Case 1 and Case 2 waters, except extremely turbid waters, are included in the simulations and sampled in the measurements. The reflectance model parameters that give the best fit with the simulated data or the measurements are determined. The accuracy of the reconstructed water reflectance and its effect on the retrieval of inherent optical properties (IOPs) is quantified. The impact of cloud and aerosol transmittance, fixed to unity in the POLYMER scheme, on model performance is also evaluated. Agreement is generally good between model results and Hydrolight simulations or AERONET-OC values, even in optically complex waters, with discrepancies much smaller than typical atmospheric correction errors. Significant differences exist in some cases, but having a more intricate model (i.e., using more parameters) makes convergence more difficult. The trade-off is between efficiency/robustness and accuracy. Notable errors are obtained when using the model estimates to retrieve IOPs. Importantly, the model parameters that best fit the input data, in particular chlorophyll-a concentration, do not represent adequately actual values. The reconstructed water reflectance should be used in bio-optical algorithms. While neglecting cloud and aerosol transmittances degrades the accuracy of the reconstructed water reflectance and the retrieved IOPs, it negligibly affects water reflectance ratios and, therefore, any variable derived from such ratios.
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Giguère, Louis A., i Robert L. Dunbrack. "Thin Layer Interference may Reduce the Visibility of Transparent Phantom Midge Larvae (Chaoborus trivittatus) to Predators". Canadian Journal of Fisheries and Aquatic Sciences 47, nr 5 (1.05.1990): 1043–46. http://dx.doi.org/10.1139/f90-119.
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The body wall of transparent aquatic animals is constructed of materials which have a higher refractive index than water. Because of this, light will reflect from their surface, making their body contours visible to predators. Electron micrographs of cuticle from the transparent pelagic stage of the phantom midge Chaoborus trivittatus reveal thin layers less than a wavelength of light thick which could alter the spectral composition of this surface reflection by acting as an interference filter. This hypothesis is supported by measurements of the reflectance of the body surface of C. trivittatus. Reflectance was lower than expected at the wavelengths which maximize contrast in aquatic environments and higher than expected at ambient background wavelengths, suggesting that interference may reduce the visibility of Chaoborus to its predators by improving the spectral matching of its body reflection to the visual background.
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Ran, Jianguo, Heng Liu i Jiqing Luo. "The color matching design based on polynomial regression". Textile Research Journal 92, nr 7-8 (27.10.2021): 1235–45. http://dx.doi.org/10.1177/00405175211054222.
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Camouflage spots are mostly color patches of different colors. Compared with the traditional empirical color matching method, computer color matching can quickly and effectively calculate the proportion of red, yellow, and blue primary colors. In general, camouflage computer color matching in the practical application of the initial formula is not accurate and multiple color modification still cannot match. First, we measured the chroma coordinates of 98 standard swatches made of red, green, and blue coatings in different proportions by the OHSP-660 spectral reflectance tester. Then, we adopted polynomial regression algorithm by Statistical Product and Service Solutions (SPSS) to obtain the regression equation between [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]. Finally, the fitting equation is used to obtain the paint color scheme in the coordinates of [Formula: see text], [Formula: see text], and [Formula: see text] in arbitrary uniform color space, so as to realize the purpose of computer color matching. The experimental results show that the minimum color difference is 1.691 ( L* a* b* unit) the maximum color difference is 2.497, which meets the design requirements of camouflage and target color difference being no more than 3. Our work provides a theoretical basis for the further development of computer color matching system in camouflage.
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Sengar, V. K., A. S. Venkatesh, P. K. Champaty Ray, S. L. Chattoraj i R. U. Sharma. "MINERALOGICAL MAPPING IN THE PART OF A GOLD PROSPECT USING EO-1 HYPERION DATA". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B7 (14.10.2016): 991–93. http://dx.doi.org/10.5194/isprs-archives-xli-b7-991-2016.
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The satellite data obtained from various airborne as well as space-borne Hyperspectral sensors, often termed as imaging spectrometers, have great potential to map the mineral abundant regions. Narrow contiguous bands with high spectral resolution of imaging spectrometers provide continuous reflectance spectra for different Earth surface materials. Detailed analysis of resultant reflectance spectra, derived through processing of hyperspectral data, helps in identification of minerals on the basis of their reflectance characteristics. EO-1 Hyperion sensor contains 196 unique channels out of 242 bands (L1R product) covering 0.4&ndash;2.5&thinsp;μm range has also been proved significant in the field of spaceborne mineral potential mapping. <br><br> Present study involves the processing of EO-1 Hyperion image to extract the mineral end members for a part of a gold prospect region. Mineral map has been generated using spectral angle mapper (SAM) method of image classification while spectral matching has been done using spectral analyst tool in ENVI. Resultant end members found in this study belong to the group of minerals constituting the rocks serving as host for the gold mineralisation in the study area.
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Bernard, E., C. Moulin, D. Ramon, D. Jolivet, J. Riedi i J. M. Nicolas. "Description and validation of an AOT product over land at the 0.6 μm channel of the SEVIRI sensor onboard MSG". Atmospheric Measurement Techniques 4, nr 11 (25.11.2011): 2543–65. http://dx.doi.org/10.5194/amt-4-2543-2011.
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Abstract. The Spinning Enhanced Visible and InfraRed Imager (SEVIRI) aboard Meteosat Second Generation (MSG) launched in 2003 by EUMETSAT is dedicated to the Nowcasting applications and Numerical Weather Prediction and to the provision of observations for climate monitoring and research. We use the data in visible and near infrared (NIR) channels to derive the aerosol optical thickness (AOT) over land. The algorithm is based on the assumption that the top of the atmosphere (TOA) reflectance increases with the aerosol load. This is a reasonable assumption except in case of absorbing aerosols above bright surfaces. We assume that the minimum in a 14-days time series of the TOA reflectance is, once corrected from gaseous scattering and absorption, representative of the surface reflectance. The AOT and the aerosol model (a set of 5 models is used), are retrieved by matching the simulated TOA reflectance with the TOA reflectances measured by SEVIRI in its visible and NIR spectral bands. The high temporal resolution of the data acquisition by SEVIRI allows to retrieve the AOT every 15 min with a spatial resolution of 3 km at sub-satellite point, over the entire SEVIRI disk covering Europe, Africa and part of South America. The resulting AOT, a level 2 product at the native temporal and spatial SEVIRI resolutions, is presented and evaluated in this paper. The AOT has been validated using ground based measurements from AErosol RObotic NETwork (AERONET), a sun-photometer network, focusing over Europe for 3 months in 2006. The SEVIRI estimates correlate well with the AERONET measurements, r = 0.64, with a slight overestimate, bias = −0.017. The sources of errors are mainly the cloud contamination and the bad estimation of the surface reflectance. The temporal evolutions exhibited by both datasets show very good agreement which allows to conclude that the AOT Level 2 product from SEVIRI can be used to quantify the aerosol content and to monitor its daily evolution with a high temporal frequency. The comparison with daily maps of Moderate Resolution Imaging Spectroradiometer (MODIS) AOT level 3 product shows qualitative good agreement in the retrieved geographic patterns of AOT. Given the high spatial and temporal resolutions obtained with this approach, our results have clear potential for applications ranging from air quality monitoring to climate studies. This paper presents a first evaluation and validation of the derived AOT over Europe in order to document the overall quality of a product that will be made publicly available to the users of the aforementioned research communities.
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Wei, Yuh Chang, Wen Min Chou i Chih Lang Chen. "The Performance of Computerized Spectrum Color Matching Based on Kubelka-Munk Theory and its Color Rendering on Offset Ink Sets". Advanced Materials Research 174 (grudzień 2010): 72–76. http://dx.doi.org/10.4028/www.scientific.net/amr.174.72.
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The purpose of the study intended to examine the performance of color rendering based on a computerized spectrum color matching (CSCM) method derived from the Kubelka-Munk theory. In the study, we prepared 2 offset ink sets to produce 30 standard color samples sets. The target color samples were measured by spectrophotometer to compare with the predicted values calculated by the CSCM model. The results showed that average measured color difference (∆E) via CIE L*a*b* and CIE DE2000 formulas between samples and CSCM predicted values averaged 5.89, 3.72 (∆Es), 6.94, 4.22(∆Epv), respectively. The measurements were fallen out the acceptable range of the tolerance of the industrial printing standards. The verification of CFI (Curve Fit Index) test came out with the same conclusion. As a result, we found that the computerized color matching formula derived from Kubelka-Munk theory still required further fine-tuning and more in-depth analysis. In addition, the reflectance database of the ink sets was another important factor affecting the performance of computer color matching model for precise colors prediction.
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Muñoz-Ramírez, Carlos P., Pierre-Paul Bitton, Stéphanie M. Doucet i Lacey L. Knowles. "Mimics here and there, but not everywhere: Müllerian mimicry in Ceroglossus ground beetles?" Biology Letters 12, nr 9 (wrzesień 2016): 20160429. http://dx.doi.org/10.1098/rsbl.2016.0429.
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The ground beetle genus Ceroglossus contains co-distributed species that show pronounced intraspecific diversity in the form of geographical colour morphs. While colour morphs among different species appear to match in some geographical regions, in others, there is little apparent colour matching. Mimicry is a potential explanation for covariation in colour patterns, but it is not clear whether the degree of sympatric colour matching is higher than expected by chance given the obvious mismatches among morphs in some regions. Here, we used reflectance spectrometry to quantify elytral coloration from the perspective of an avian predator to test whether colour similarity between species is, indeed, higher in sympatry. After finding no significant phylogenetic signal in the colour data, analyses showed strong statistical support for sympatric colour similarity between species despite the apparent lack of colour matching in some areas. We hypothesize Müllerian mimicry as the responsible mechanism for sympatric colour similarity in Ceroglossus and discuss potential explanations and future directions to elucidate why mimicry has not developed similar levels of interspecific colour resemblance across space.
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Chen, Qiao, Li Jie Wang i Stephen Westland. "A Novel Method for Representation of Spectral Images Based on Color Matching Functions". Advanced Materials Research 181-182 (styczeń 2011): 410–15. http://dx.doi.org/10.4028/www.scientific.net/amr.181-182.410.
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Spectral images contain a large volume of data and the development of multispectral imaging systems places considerable demands on computer hardware and software compared with standard three-component or trichromatic image storage and processing. This study is concerned with lossy compression techniques for spectral images since many color images are intended for display for human perception and it is well established that images contain redundancies (in terms of their color, spatial and temporal properties) that can be removed without any loss in image quality. The lossy compression technique that is considered in this work is a low-dimensional linear model of spectral reflectance, with which the basis function are derived from color matching functions that are correlated with human visual system.
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Ham, S. H., i B. J. Sohn. "Assessment of the calibration performance of satellite visible channels using cloud targets: application to Meteosat-8/9 and MTSAT-1R". Atmospheric Chemistry and Physics Discussions 10, nr 5 (17.05.2010): 12629–64. http://dx.doi.org/10.5194/acpd-10-12629-2010.
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Abstract. To examine the calibration performance of the Meteosat-8/9 Spinning Enhanced Visible Infra-Red Imager (SEVIRI) 0.640-μm and the Multi-functional Transport Satellite (MTSAT)-1R 0.724-μm channels, three calibration methods were employed. First, a ray-matching technique was used to compare Meteosat-8/9 and MTSAT-1R visible channel reflectances with the well-calibrated Moderate Resolution Imaging Spectroradiometer (MODIS) 0.646-μm channel reflectances. Spectral differences of the response function between the two channels of interest were taken into account for the comparison. Second, collocated MODIS cloud products were used as inputs to a radiative transfer model to calculate Meteosat-8/9 and MTSAT-1R visible channel reflectances. In the simulation, the three-dimensional radiative effect of clouds was taken into account and was subtracted from the simulated reflectance to remove the simulation bias caused by the plane-parallel assumption. Third, an independent method used the typical optical properties of deep convective clouds (DCCs) to simulate reflectances of selected DCC targets. Although the three methods were not in perfect agreement, the results suggest that calibration accuracies were within 5–10% for the Meteosat-8 0.640-μm channel, 4–9% for the Meteosat-9 0.640-μm channel, and up to 20% for the MTSAT-1R 0.724-μm channel. The results further suggest that the solar channel calibration scheme combining the three methods in this paper can be used as a tool to monitor the calibration performance of visible sensors that are particularly not equipped with an onboard calibration system.
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SKILES, S. McKENZIE, THOMAS PAINTER i GREGORY S. OKIN. "A method to retrieve the spectral complex refractive index and single scattering optical properties of dust deposited in mountain snow". Journal of Glaciology 63, nr 237 (14.12.2016): 133–47. http://dx.doi.org/10.1017/jog.2016.126.
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ABSTRACTDust deposition to snow can have regionally important climatic and hydrologic impacts resulting from direct reduction of surface albedo and indirectly from the initiation of snow albedo feedbacks. Modeling the radiative impacts of dust deposited in snow requires knowledge of the optical properties of both components. Here we present an inversion technique to retrieve the effective optical properties of dust deposited in mountain snow cover from measurements of hemispherical dust reflectance and particle size distributions using radiative transfer modeling. First, modeled reflectance is produced from single scattering properties modeled with Mie theory for a specified grain size distribution over a range of values for the imaginary part of the complex refractive index (k = 0.00001–0.1). Then, a multi-step look-up table process is employed to retrieve kλ and single scattering optical properties by matching measured to modeled reflectance across the shortwave and near infrared. The real part of the complex refractive index, n, for dust aerosols ranges between 1.5 and 1.6 and a sensitivity analysis shows the method is relatively insensitive to the choice of n within this range, 1.525 was used here. Using the values retrieved by this method to update dust optical properties in a snow + aerosol radiative transfer model reduces errors in springtime albedo modeling by 50–70%.
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Plotnikov, Dmitry, Pavel Kolbudaev, Alexey Matveev, Andrey Proshin i Ivan Polyanskiy. "Accuracy Assessment of Atmospheric Correction of KMSS-2 Meteor-M #2.2 Data over Northern Eurasia". Remote Sensing 15, nr 18 (7.09.2023): 4395. http://dx.doi.org/10.3390/rs15184395.
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Atmospheric correction of satellite remote sensing data is a prerequisite for a large variety of applications, including time series analysis and quantitative assessment of the Earth’s vegetation cover. It was earlier reported that an atmospherically corrected KMSS-M (Meteor-M #2) dataset was produced for Russia and neighboring countries. The methodology adopted for atmospheric correction was based on localized histogram matching of target KMSS-M and MODIS reference gap-free and date-matching imagery. In this paper, we further advanced the methodology and quantitatively assessed Level-2 surface reflectance analysis-ready datasets, operatively produced for KMSS-2 instruments over continental scales. Quantitative assessment was based on accuracy, precision, and uncertainty (APU) metrics produced for red and near-infrared bands of the KMSS-2 instrument based on a reference derived from a MODIS MOD09 reconstructed surface reflectance. We compared error distributions at 5%, 20%, and 50% levels of cloudiness and indicated that the cloudiness factor has little impact on the robustness of the atmospheric correction regardless of the band. Finally, the spatial and temporal gradients of accuracy metrics were investigated over northern Eurasia and across different seasons. It was found that for the vast majority of observations, accuracy falls within the −0.010–0.035 range, while precision and uncertainty were below 0.06 for any band. With the successful launch of the most recent Meteor-M #2.3 with a new KMSS-2 instrument onboard, the efficiency and interoperability of the constellation are expected to increase.
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Parker, Andrew R., David R. Mckenzie i Maryanne C. J. Large. "Multilayer reflectors in animals using green and gold beetles as contrasting examples". Journal of Experimental Biology 201, nr 9 (1.05.1998): 1307–13. http://dx.doi.org/10.1242/jeb.201.9.1307.
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The light reflectors in the beetles Calloodes grayanus and Anoplognathus parvulus are examined. Contrasting multilayer reflectors are revealed. Calloodes grayanus appears a weak green colour, matching its background leaves, while A. parvulus is strongly metallic-gold coloured. The former reflection is diffuse, as the result of a structure causing scattering that overlies the multilayer reflector, whereas the latter reflection is strongly directional. The green colour of C. grayanus is achieved by a multilayer reflector with a fixed spatial periodicity, here termed 'regular', which is far removed from the quarterwave, or physically 'ideal', condition. The gold colour of A. parvulus is achieved by a type of reflector which involves systematically changing optical thicknesses of the component layers with depth in the structure. A layer of melanin underlies the reflector of C. grayanus to absorb the transmitted portion of light and prevent its back-reflectance, which would otherwise alter the green colour. The resultant structural reflectance from C. grayanus effectively matches green pigments, which are rare in beetles.
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Tittl, Andreas, Moshe G. Harats, Ramon Walter, Xinghui Yin, Martin Schäferling, Na Liu, Ronen Rapaport i Harald Giessen. "Quantitative Angle-Resolved Small-Spot Reflectance Measurements on Plasmonic Perfect Absorbers: Impedance Matching and Disorder Effects". ACS Nano 8, nr 10 (6.10.2014): 10885–92. http://dx.doi.org/10.1021/nn504708t.
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HARA, Yoshitaka, Hirohiko KAWATA, Akihisa OHYA i Shin'ichi YUTA. "2P1-C29 Mobile Robot Localization by Scan Matching using Laser Reflectance Intensity of the SOKUIKI Sensor". Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2006 (2006): _2P1—C29_1—_2P1—C29_4. http://dx.doi.org/10.1299/jsmermd.2006._2p1-c29_1.
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Osborne, B. G., Z. Kotwal, I. J. Wesley, L. Saunders, P. Dardenne i J. S. Shenk. "Optical Matching of near Infrared Reflectance Monochromator Instruments for the Analysis of Ground and Whole Wheat". Journal of Near Infrared Spectroscopy 7, nr 3 (czerwiec 1999): 167–78. http://dx.doi.org/10.1255/jnirs.247.
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Polavarapu, Prasad L., i Zhengyu Deng. "Differential Polarized Reflectance Spectroscopy at Air/Water and Air/Metal Interfaces". Applied Spectroscopy 50, nr 1 (styczeń 1996): 91–97. http://dx.doi.org/10.1366/0003702963906807.
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We report the direct measurement of differential polarized reflectance spectra for samples at air/water and air/metal interfaces. The central component for these measurements is a polarization-division interferometer (PDI). This interferometer uses an in-house-designed beamsplitter constructed in-house from a BaF2 polarizer and a matching substrate. In conjunction with a linear polarizer in front of the source and two rooftop mirrors, one in each arm of the interferometer, the PDI divides the input beam into two orthogonal linear polarization components, recombines them for interference at the beamsplitter, and directs the output beam at 90° to the direction of the input beam. Collimated light rays exiting the interferometer are focused by an f/5 lens and bent from the horizontal propagating axis by a ZnSe wedge to give an angle of incidence of ∼75°, at the sample. The reflected rays are brought back to the horizontal propagation direction by another ZnSe wedge and focused onto the detector by an f/1 lens. The interferogram obtained in this manner represents the differential polarized reflectance interferogram whose cosine Fourier transform directly gives the differential polarized reflectance spectrum. Thus, these spectra were obtained without need for the commonly used photoelastic modulator. Representative spectra for monolayers on a water surface and for samples on a gold surface are presented.
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Ding, Xia, Wei Peng i Xiaoling Yi. "Evaluation of Physical Education Teaching Effect Based on Action Skill Recognition". Computational Intelligence and Neuroscience 2022 (31.05.2022): 1–11. http://dx.doi.org/10.1155/2022/9489704.
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In order to improve the effect of physical education teaching in modern colleges and universities, this paper combines the movement skill recognition algorithm to construct a physical education effect evaluation system and studies the multispectral image reproduction system in practical application. Moreover, this paper gives a detailed description of more advanced functional modules in the system, such as spectral acquisition, spectral reflectance reconstruction, and spectral color correction. In addition, this paper focuses on the algorithm design of the color appearance matching module. By adding the “color appearance transformation” on the source side and the “color appearance inversion” on the reproduction side, the source image and the reproduced image can achieve color appearance matching in the observation condition-independent space. The simulation experiment verifies that the physical education effect evaluation system based on action skill recognition meets the actual needs of physical education and has a good role in promoting the recognition of physical skills and the improvement of physical education effect.
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Boker, Steven M. "A Measurement of the Adaptation of Color Vision to the Spectral Environment". Psychological Science 8, nr 2 (marzec 1997): 130–34. http://dx.doi.org/10.1111/j.1467-9280.1997.tb00695.x.
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An exploratory factor analysis of the reflectance spectral distributions of a sample of natural and man-made objects yields a factor pattern remarkably similar to psychophysical color-matching curves. The goodness-of-fit indices from a maximum likelihood confirmatory factor model with fixed factor loadings specified by empirical trichromatic color-matching data indicate that the human visual system performs near to an optimum value for an ideal trichromatic system composed of three linear components. An unconstrained four-factor maximum likelihood model fits significantly better than a three-factor unconstrained model, suggesting that a color metric is better represented in four dimensions than in a three-dimensional space. This fourth factor can be calculated as a nonlinear interaction term between the first three factors: thus, a trichromatic input is sufficient to compute a color space of four dimensions. The visual system may exploit this nonlinear dependency in the spectral environment in order to obtain a four-dimensional color space without the biological cost of a fourth color receptor.
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Deneke, H. M., i R. Roebling. "Downscaling of METEOSAT SEVIRI 0.6 and 0.8 micron channel radiances utilizing the high-resolution visible channel". Atmospheric Chemistry and Physics Discussions 10, nr 4 (23.04.2010): 10707–40. http://dx.doi.org/10.5194/acpd-10-10707-2010.
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Abstract. An algorithm is introduced to downscale the 0.6 and 0.8 micron spectral channels of the METEOSTAT SEVIRI satellite imager from 3×3 km2 (LRES) to 1×1 km2 (HRES) resolution utilizing SEVIRI's high-resolution visible channel (HRVIS). Intermediate steps include the coregistration of low- and high-resolution images, lowpass filtering of the HRVIS channel with the spatial response function of the narrowband channels, and the estimation of a least-squares linear regression model for linking high-frequency variations in the HRVIS and narrowband images. The importance of accounting for the sensor spatial response function for matching reflectances at different spatial resolutions is demonstrated, and an estimate of the accuracy of the downscaled reflectances is provided. Based on a 1-year dataset of Meteosat SEVIRI images, it is estimated that on average, the reflectance of a HRES pixel differs from that of an enclosing LRES pixel by standard deviations of 0.049 and 0.052 in the 0.6 and 0.8 micron channels, respectively. By applying our downscaling algorithm, explained variance of 98.2 and 95.3 percent are achieved for estimating these deviations, corresponding to residual standard deviations of only 0.007 and 0.011 for the respective channels. For this dataset, a minor misregistration of the HRVIS channel relative to the narrowband channels of 0.36±0.11 km in East and 0.06±0.10 km in South direction is observed and corrected for, which should be negligible for most applications.
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Deneke, H. M., i R. A. Roebeling. "Downscaling of METEOSAT SEVIRI 0.6 and 0.8 μm channel radiances utilizing the high-resolution visible channel". Atmospheric Chemistry and Physics 10, nr 20 (18.10.2010): 9761–72. http://dx.doi.org/10.5194/acp-10-9761-2010.
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Abstract. An algorithm is introduced to downscale the 0.6 and 0.8 μm spectral channels of the METEOSTAT SEVIRI satellite imager from 3×3 km2 (LRES) to 1×1 km2 (HRES) resolution utilizing SEVIRI's high-resolution visible channel (HRV). Intermediate steps include the coregistration of low- and high-resolution images, lowpass filtering of the HRV channel with the spatial response function of the narrowband channels, and the estimation of a least-squares linear regression model for linking high-frequency variations in the HRV and narrowband images. The importance of accounting for the sensor spatial response function for matching reflectances at different spatial resolutions is demonstrated, and an estimate of the accuracy of the downscaled reflectances is provided. Based on a 1-year dataset of Meteosat SEVIRI images, it is estimated that on average, the reflectance of a HRES pixel differs from that of an enclosing LRES pixel by standard deviations of 0.049 and 0.052 in the 0.6 and 0.8 μm channels, respectively. By applying our downscaling algorithm, explained variance of 98.2 and 95.3 percent are achieved for estimating these deviations, corresponding to residual standard deviations of only 0.007 and 0.011 for the respective channels. For this dataset, a minor misregistration of the HRV channel relative to the narrowband channels of 0.36±0.11 km in East and 0.06±0.10 km in South direction is observed and corrected for, which should be negligible for most applications.
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Querques, Giuseppe, Marco R. Pastore, Houda Khlifi, Anouk Georges, Lea Querques i Eric H. Souied. "Integrated Imaging of Avascular Serous Pigment Epithelium Detachment in Age-related Macular Degeneration". Ophthalmology @ Point of Care 1, nr 1 (styczeń 2017): oapoc.0000009. http://dx.doi.org/10.5301/oapoc.0000009.
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Introduction This study describes the imaging of avascular serous pigment epithelial detachment (PED) in age-related macular degeneration (AMD) patients using confocal scanning laser ophthalmoscopy and spectral-domain optical coherence tomography (SD-OCT). Methods A total of 18 patients with avascular serous PED underwent assessment of best-corrected visual acuity, infrared (IR) reflectance, fundus autofluorescence (FAF), fluorescein angiography (FA), indocyanine green angiography (ICGA), and SD-OCT evaluation at baseline and at last follow-up visit. The imaging of avascular PED was compared with vascularized PED. Results A total of 23 eyes with 15.5 ± 6.4 months’ follow-up were included. Imaging revealed 3 features associated with avascular serous PED. A reticular pattern, highly reflective (IR), and hyperautofluorescent matching with a reticular area of decreased fluorescence (FA and ICGA) was constantly observed (23/23 eyes). This reticular pattern correlated on SD-OCT with dense hypereflective deposits beneath and within the sensory retina. This reticular pattern was observed in only 2/19 eyes with vascular serous PED (p<0.05). A sharp border of increased IR reflectance, matching with a halo of reduced fluorescence on both FAF and late FA frames, was observed in 23/23 eyes. This sharp border appeared as a sharp hypofluorescent border on late ICGA frames, and as an abrupt elevation of the retinal pigment epithelium on SD-OCT. Hyporeflective fluid beneath the foveal depression was observed in 17/23 (74%) eyes. Only 1/23 eyes developed choroidal neovascularization during the follow-up. Conclusions Integrated imaging shows peculiar features of avascular PED and possibly contributes to distinguishing this clinical identity from neovascular AMD.
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Jia, Shoujun, Chun Liu, Hangbin Wu i Chen Chen. "Image enhancement method for visual localization and mapping in complex light scenarios". IOP Conference Series: Earth and Environmental Science 1004, nr 1 (1.03.2022): 012014. http://dx.doi.org/10.1088/1755-1315/1004/1/012014.
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Abstract Visual localization and mapping have received considerable attention in the fields of computer vision, photogrammetry, and remote sensing. Image matching is key to visual localization and mapping. However, light is complex and uneven in real scenarios, creating difficulties in feature extraction and matching. Hence, feature mismatch and loss reduce the efficiency, accuracy, and robustness of visual localization and mapping. We developed a visual localization and mapping method for complex light scenarios based on image enhancement. Starting with initial images, the irradiance and reflectance components were separated based on logarithmic transformation. Our method strengthened high-frequency components and restrained low-frequency components with improved homomorphic filtering, restraining the light component and enhancing the important reflection component. The SIFT algorithm was used for feature detection and matching. The proposed method was tested on images with uneven light captured using a stereo vision camera in an indoor environment, focusing on visual localization and mapping. The experimental results emphasized that the method improved the rate of image localization and number of point clouds, as well as the reprojection error, which ranged from 0.85 to 0.82 on average. Thus, the proposed method is robust rather than probabilistic for improving visual localization and mapping under complex light conditions.
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Su, Ye, Ye Yutang, Xie Yu, Yi Maoli, Zhang Jing, Luo Ying i Du Chunlei. "Swift perspective shape matching algorithm based on Phong’s model for FPC stiffener bonding systems". Circuit World 40, nr 4 (28.10.2014): 141–49. http://dx.doi.org/10.1108/cw-06-2014-0023.
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Purpose – This paper aims to solve the issue of target positioning in auto stiffener bonder (ASB) systems for flexible printed circuits. Design/methodology/approach – The proposed approach uses Phong’s bidirectional reflectance distribution function (BRDF) model to simulate the reflection of light off a target in ASB systems to predict the current pose of the target based on image brightness, update the template, decrease the initial errors in the template and narrow down the search range. Findings – The experimental results indicate that the proposed approach can predict the inclination angle of the target with precision, presenting angle prediction errors of less than three degrees. Furthermore, with larger inclined angles, the overall matching errors were less than 1.5 pixels. Comparisons with the unmodified matching algorithm revealed that the proposed approach resulted in 65 per cent less calculation time for the algorithm and 14 per cent higher overall work efficiency in the ASB system. Originality/value – The edge-based perspective shape matching algorithm was modified using the Phong BRDF model and enhanced algorithm efficiency with the target pose prediction method while ensuring the precision and robustness of the system. The proposed approach has high potential value and can be expanded to recognition systems for objects with varying inclination angles and highly reflective surfaces.
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Ham, S. H., i B. J. Sohn. "Assessment of the calibration performance of satellite visible channels using cloud targets: application to Meteosat-8/9 and MTSAT-1R". Atmospheric Chemistry and Physics 10, nr 22 (25.11.2010): 11131–49. http://dx.doi.org/10.5194/acp-10-11131-2010.
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Abstract. To examine the calibration performance of the Meteosat-8/9 Spinning Enhanced Visible Infra-Red Imager (SEVIRI) 0.640-μm and the Multi-functional Transport Satellite (MTSAT)-1R 0.724-μm channels, three calibration methods are employed. Total eight months during the 2004–2007 period are used for SEVIRI, and total seven months during the 2007–2008 period are used for MTSAT-1R. First, a ray-matching technique is used to compare Meteosat-8/9 and MTSAT-1R visible channel reflectances with the well-calibrated Moderate Resolution Imaging Spectroradiometer (MODIS) 0.646-μm channel reflectances. Spectral differences of the response function between the two channels of interest are taken into account for the comparison. Second, collocated MODIS cloud products are used as inputs to a radiative transfer model (RTM) to calculate Meteosat-8/9 and MTSAT-1R visible channel reflectances. In the simulation, cloud three-dimensional (3-D) radiative effect associated with subgrid variations is taken into account using the lognormal-independent column approximation (LN-ICA) to minimize the simulation bias caused by the plane-parallel homogeneous assumption. Third, an independent method uses the typical optical properties of deep convective clouds (DCCs) to simulate reflectances of selected DCC targets. Although all three methods are not in perfect agreement, the results suggest that calibration coefficients of Meteosat-8/9 0.640-μm channels are underestimated by 6–7%. On the other hand, the calibration accuracy of MTSAT-1R visible channel appears to be variable with the target reflectance itself because of an underestimate of calibration coefficient (up to 20%) and a non-zero space offset. The results further suggest that the solar channel calibration scheme combining the three methods in this paper can be used as a tool to monitor the calibration performance of visible sensors that are particularly not equipped with an onboard calibration system.
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Gillis, J. E. "Selection for Substrate Reflectance-matching in Two Populations of Red-chinned Lizards (Sceloporus undulatus erythrocheilus) from Colorado". American Midland Naturalist 121, nr 1 (styczeń 1989): 197. http://dx.doi.org/10.2307/2425672.
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Wang, Yanming, Yiu-lun Tang, Cheng-hao Lee i Chi-Wai Kan. "A Computer Color-Matching Study of Reverse Micellar Dyeing of Wool with Reactive Dyes". Polymers 11, nr 1 (14.01.2019): 132. http://dx.doi.org/10.3390/polym11010132.
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Computer color-matching (CCM) and the levelness of poly(ethylene glycol)-based reverse-micellar dyed wool fabrics in octane and nonane were investigated and compared with a conventional water-based dyeing system. Reflectance curves and calibration curves exhibited no chromatic change and maintained high linearity in both dyeing systems. The linearity of water-dyed calibration curves was slightly higher than that of the reverse-micellar dyed curves. The color yield, in term of K/Ssum values, of solvent-dyed samples was found to be generally higher than that of water-based dyed samples at various calibrated dye concentrations. The concentrations predicted by CCM were close to the theoretical concentrations for both dyeing methods. This indicates that octane- and nonane-assisted reverse-micellar dyeing of wool is able to generate color recipes comparable to the conventional water-based dyeing system. The solvent-dyed samples, measured by the relative unlevelness indices (RUI), exhibit good-to-excellent levelness, which is highly comparable with the water-dyed samples.