Scott Ramsey
United States Naval Research Laboratory
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Publication
Featured researches published by Scott Ramsey.
Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral Imagery XXIV | 2018
R. Viger; Scott Ramsey; Troy Mayo; S. G. Lambrakos
This study describes a parametric model of diffuse reflectance for the purpose of simulating the spectral response of near-infrared (NIR, 0.7-0.9 μm) and shortwave infrared (SWIR, 0.9-1.7 μm) absorbing dyes for tailoring the NIR-SWIR reflectance of fabrics. This model combines diffuse-reflectance theory with reference spectra for simulating absorption in fabric of NIR/SWIR absorbing dyes whose absorption spectra span the NIR/SWIR spectral range. Fabric samples consisting of a cotton blend were used as the test substrate for NIR/SWIR dye application. The results of this study demonstrate application of the parametric model for simulating NIR/SWIR spectral responses corresponding to variable dye and dye blend concentrations in fabrics.
Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral Imagery XXIV | 2018
S. G. Lambrakos; Scott Ramsey; Troy Mayo
Advanced combat uniforms with multiple tonal (blended) colors and highly detailed camouflage patterning require additional test methodologies for color evaluation. Here the apparent color, which is the combination of all visible wavelengths (380-700 nm) of light reflected from large (≥1m2) fabric sample sizes for a given standoff distance (25-100 ft), is evaluated as a potential test method. Camouflage patterns lose resolution with increasing standoff distance, and eventually all colors within the pattern appear monotone (the “apparent color” of the camouflage pattern). This paper presents a case-study analysis using apparent color for the purpose of model development relevant to evaluating color in camouflage fabrics.
Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral Imagery XXIV | 2018
S. G. Lambrakos; Chris Howells; Andrew Shabaev; Troy Mayo; Scott Ramsey
Advanced camouflage patterns for military applications consist of highly detailed camouflage patterning and multiple tonal (blended) colors. The complexity of these camouflage patterns establishes a need for additional test methodologies for color and pattern evaluation. One metric for evaluation is apparent color, which is the combination of all visible wavelengths (380-700 nm) of light reflected from large (≥1m2) fabric sample sizes for a given standoff distance (25-100 ft). This follows in that camouflage patterns lose resolution with increasing standoff distance, and eventually all colors within the pattern appear monotone (the “apparent color” of the camouflage pattern). The concept of apparent color, however, is based on far-field and statistical characteristics of camouflage patterns. In contrast, the concept of apparent camouflage pattern is to be associated with intermediate distances between observer and target. Accordingly, quantitative metrics for camouflage-pattern viability based on apparent patterns should be different than those for apparent color, thus providing additional criteria for evaluation. This paper presents discussion and prototype simulations based on the concept of apparent camouflage pattern for model development relevant to evaluating camouflage fabrics.
Optics and Photonics for Information Processing XI | 2017
Andrew Shabaev; Scott Ramsey; Troy Mayo; S. G. Lambrakos
As the U.S. Navy, Army, and Special Operations Forces progress towards fielding more advanced uniforms with multi-colored and highly detailed camouflage patterning, additional test methodologies are necessary in evaluating color in these types of camouflage textiles. The apparent color is the combination of all visible wavelengths (380-760 nm) of light reflected from large (≥1m2 ) fabric sample sizes for a given standoff distance (10-25ft). Camouflage patterns lose resolution with increasing standoff distance, and eventually all colors within the pattern appear monotone (the “apparent color” of the pattern). This paper presents an apparent color prediction model that can be used for evaluation of camouflage fabrics.
Journal of Electromagnetic Waves and Applications | 2017
Scott Ramsey; Troy Mayo; S. G. Lambrakos
Abstract This study describes a parametric model of diffuse reflectance for the purpose of simulating the spectral response of near-infrared (NIR, 0.7–0.9 μm) and shortwave infrared (SWIR, 0.9–1.7 μm) absorbing dyes for minimizing NIR-SWIR reflectance of dyed fabrics. This model is purely phenomenological, but is optimal with respect to numbers of parameters. This model establishes ground-work for development of a prediction tool, which when given the constituent materials available, will enable rapid optimization of NIR/SWIR band contrast matching of composite systems, (e.g. uniforms and ancillary gear) for a given specification of NIR-SWIR reflectance. This model adopts absorption coefficients for NIR/SWIR absorbing dyes whose absorption spectra span the NIR/SWIR spectral range. Military camouflage fabric consisting of 50/50 nylon/cotton blend in a ripstop weave printed with four-color digital pattern was used as the test substrate for NIR/SWIR dye application. The results of this study provide validation of the parametric model within reasonable error, for practical applications including simulating NIR/SWIR spectral responses corresponding to fixed dye and dye blend concentrations in prototype camouflage fabrics.
Journal of Electromagnetic Waves and Applications | 2017
Scott Ramsey; Troy Mayo; S. G. Lambrakos
Abstract An inverse analysis of transmission spectra for near-infrared (NIR, 0.7–0.9 μm) and shortwave infrared (SWIR, 0.9–1.7 μm) absorbing dyes in solution is presented. This analysis employs a parametric model of transmission through a sample of finite thickness, where the permittivity function is represented parametrically by a linear combination of Lorentz oscillator models. The results of this analysis provide estimates of permittivity functions, which can be adopted as input data to other types of models, such as those for prediction of transmission and reflectivity spectra for composites containing mixtures of dyes and other materials. In addition, the results of this analysis should contribute to a database of estimated permittivity functions for practical analysis of spectra.
SPIE Commercial + Scientific Sensing and Imaging | 2016
Daniel C. Aiken; Scott Ramsey; Troy Mayo; S. G. Lambrakos; Joseph Peak
This study examines parametric modeling of NIR reflectivity spectra for dyed fabrics, which provides for both their inverse and direct modeling. The dye considered for prototype analysis is triarylamine dye. The fabrics considered are camouflage textiles characterized by color variations. The results of this study provide validation of the constructed parametric models, within reasonable error tolerances for practical applications, including NIR spectral characteristics in camouflage textiles, for purposes of simulating NIR spectra corresponding to various dye concentrations in host fabrics, and potentially to mixtures of dyes.
Advanced Environmental, Chemical, and Biological Sensing Technologies XIII | 2016
S. G. Lambrakos; C. Yapijakis; Daniel C. Aiken; Andrew Shabaev; Scott Ramsey; Joseph Peak
Monitoring of contaminants associated with specific water resources using transmission spectra, with respect to types and relative concentrations, requires tracking statistical profiles of water contaminants in terms of spatial-temporal distributions of electromagnetic absorption spectra ranging from the ultraviolet to infrared. For this purpose, correlation between spectral signatures and types of contaminants within specific water resources must be made, as well as correlation of spectral signatures with results of processes for removal of contaminants, such as ozonation. Correlation between absorption spectra and changes in chemical and physical characteristics of contaminants, within a volume of sampled solution, requires sufficient sensitivity. The present study examines the sensitivity of transmission spectra with respect to general characteristics of water contaminants for spectral analysis of water samples.
Proceedings of SPIE | 2015
Daniel C. Aiken; Scott Ramsey; Troy Mayo; James Bellemare; S. G. Lambrakos; Joseph Peak
Inverse analysis of transmission spectra for triarylamine dye in acetone is presented. This analysis employs a parametric model of transmission through a sample of finite thickness, where the permittivity function is represented parametrically by a linear combination of Lorentz oscillator models. The results of this analysis provide estimates of the permittivity function for triarylamine dye, which can be adopted as input data to other types of models, such as those for prediction of transmission and reflectivity spectra for composites containing mixtures of dyes and other materials. In addition, the results of this analysis should contribute to a data base of estimated permittivity functions for practical analysis of spectra.
Optical Engineering | 2015
Daniel C. Aiken; Scott Ramsey; Troy Mayo; S. G. Lambrakos; Joseph Peak
Abstract. Inverse analysis of transmission spectra for triarylamine dye in acetone is presented. This analysis employed a parametric model of transmission through a sample of finite thickness, where the permittivity function was represented parametrically by a linear combination of Lorentzian functions. The results of this analysis provided estimates of the permittivity function for triarylamine dye, which can be adopted as input data to other types of models, such as those for prediction of transmission and reflectivity spectra for composites containing mixtures of dyes and other materials. In addition, this analysis demonstrated that the absorption coefficients for a dye, which were obtained by inverse analysis of transmission spectra for that dye in solution, can be validated as reasonable estimates of the absorption coefficients for that dye in fabric.