scholarly journals Evaluating simple proxy measures for estimating depth of the ~1900nm water absorption feature from hyperspectral data acquired under natural illumination

2015 ◽  
Vol 166 ◽  
pp. 22-33 ◽  
Author(s):  
Richard J. Murphy
Keyword(s):  
Water Absorption ◽  
Hyperspectral Data ◽  
Absorption Feature ◽  
Natural Illumination

scholarly journals Hydat-A Hyperspectral Data Processing Tool for Field Spectroradiometer Data

2014 ◽  
Vol XL-8 ◽  
pp. 481-484
Author(s):  
S. Singh ◽  
D. Dutta ◽  
U. Singh ◽  
J. R. Sharma ◽  
V. K. Dadhwal
Keyword(s):  
Signal Processing ◽  
Data Processing ◽  
Noise Removal ◽  
Hyperspectral Data ◽  
Spectral Geometry ◽  
Spectral Space ◽  
Smoothing Function ◽  
Absorption Feature ◽  
Report Generation ◽  
Data Processing Tool

A hyperspectral data processing tool "HyDAT" has been developed in MATLAB environment for processing of Field Spectroradiometer data for vegetation studies. Several basic functions e.g. data visualization, pre-processing, noise removal and data transformation and features like automatic absorption feature recovery and their characterization have been introduced. A new concept of spectral geometry has been included as a separate module which is conceptualized as triangle formed over spectral space joining the vertices of green reflectance peak, red well and inflection point and is extremely useful for vegetation health analysis. A large variety of spectral indices both static and dynamic, have been introduced which is useful for remote estimation of foliar biochemicals. Keeping in view the computational requirement, MATLAB was used in the programming environment. It has various in-built functions for statistical and mathematical analysis, signal processing functions like FFT (Fast Fourier Transform), CWT (Continuous Wavelet Transform), direct smoothing function for moving average, Savitzky-Golay smoothing technique, etc. which can be used with ease for the signal processing and field data analysis. FSF (Field Spectroscopy Facility) Post processing Toolbox can also be freely downloaded and can be used for the direct importing and pre-processing of Spectroradiometer data for detector overlap correction, erroneous water band removal and smoothing. The complete package of the software has been bundled for standalone application of shared libraries with additional files for end users. The software is powered by creation of spectral library and customized report generation. An online help menu guides the user for performing different functions. The tool is capable of reducing the time required for processing field based hyperspectral data significantly and eliminate the need for different software to process the raw data and spectral features extraction.

scholarly journals Atmospherically resistant vegetation water indices using the 970-nm water absorption feature

2020 ◽  
Vol 14 (03) ◽  
pp. 1
Author(s):  
Quanjun Jiao ◽  
Liangyun Liu ◽  
Jiangui Liu ◽  
Hao Zhang ◽  
Bing Zhang
Keyword(s):  
Water Absorption ◽  
Absorption Feature ◽  
Vegetation Water ◽  
Water Indices

scholarly journals Feature Extraction and Clustering of Hyperspectral Drill Core Measurements to Assess Potential Lithological and Alteration Boundaries

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 136
Author(s):  
Andrew Rodger ◽  
Adrian Fabris ◽  
Carsten Laukamp
Keyword(s):  
Feature Extraction ◽  
South Australia ◽  
Hyperspectral Data ◽  
Three Dimensions ◽  
Absorption Feature ◽  
Drill Core ◽  
Efficient Manner ◽  
Mineral Assemblages ◽  
Absorption Features ◽  
Drill Cores

A workflow incorporating hyperspectral reflectance data, hull corrections, absorption feature extraction and clustering is presented. The workflow is applied to dense hyperspectral datasets, as collected by hyperspectral drill core logging systems. The extracted absorption features of the reflectance spectra collected from drill cores are shown to form assemblage clusters when plotting the wavelength position of the first, second and third deepest absorption features in two and three dimensions. Using an unsupervised clustering method to establish clusters based on the extracted absorption features yields viewable down hole distributions of similar mineral assemblages. The proposed workflow has the potential for the rapid identification of differing lithologies, alteration and/or weathering overprints. Application of the workflow with no a-priori assumptions about the composition of the potential mineral assemblages provides a means of generating an informative overview of the dataset that is not biased or constrained by preconceptions. The workflow can easily be added to the current workflows of geologists whom are working with dense hyperspectral data to provide an overview of the potential down hole mineral assemblages and aid in the visual logging process or assist in quickly identifying areas for more detailed observation. Furthermore, key mineralogical parameters for resource characterisation, such as the presence of clay minerals can be assessed in a cost and time efficient manner. The proposed workflow is applied to spectra collected from four different drill cores collected in the Gawler Craton located in South Australia and demonstrates the potential outlined above.

NIPAM polymer/polyurethane resin films and the moisture transport characteristics of film-treated fabrics

2020 ◽  
pp. 004051752094569
Author(s):  
Masao Enomoto ◽  
Yuichiro Omote ◽  
Mitsuo Miyajima ◽  
Che Kyung Yun
Keyword(s):  
Water Absorption ◽  
Moisture Transport ◽  
Water Solubility ◽  
Functional Materials ◽  
Solution Temperature ◽  
Absorption Feature ◽  
Temperature Sensitive ◽  
Water Absorption Coefficient ◽  
Solubility In Water ◽  
Copolymer Films

Numerous studies have addressed the use of poly( N-isopropylacrylamide) or (poly-NIPAM) homopolymers in drug delivery systems. However, their application has not been extended to textiles owing to their high solubility in water. In this study, we investigated thermo-responsive, hydrophilic, breathable, waterproof films as well as fabrics treated with these films. To impart temperature-sensitivity, a poly-NIPAM polymer was used, with water solubility at or below the lower critical solution temperature (LCST). The poly-NIPAM used in this study had to be insoluble in water, even at the LCST or below it. Consequently, this study was performed using films wherein poly-NIPAM was copolymerized with hydrophilic polyurethane (PU). The change in water solubility of the homopolymer at temperatures greater than or less than the LCST could be verified from the water absorption coefficient of the films observed at various temperatures. Subsequently, we ascertained the functionality of the temperature-sensitive water absorption feature. In addition, we validated the functionality of the breathable, waterproof films and the condensation-inhibition capacity of film-treated fabrics. As a result, we postulated that the fabrics coated with poly-NIPAM/PU copolymer films could serve as functional materials for apparel with novel and improved moisture transport characteristics.

scholarly journals Temperature and Emissivity Separation ‘Draping’ Algorithm Applied to Hyperspectral Infrared Data

2020 ◽  
Vol 12 (12) ◽  
pp. 2046
Author(s):  
Valerio Lombardo ◽  
Leonie Pick ◽  
Claudia Spinetti ◽  
Jacopo Tadeucci ◽  
Klemen Zakšek
Keyword(s):  
Radiant Energy ◽  
Spectral Emissivity ◽  
Hyperspectral Data ◽  
Spectral Radiance ◽  
Absorption Feature ◽  
Atmospheric Window ◽  
Magmatic Temperature ◽  
Melting Surface ◽  
Two Temperatures ◽  
First Time

In the presented work, the spectral emissivity of basaltic melts at magmatic temperatures was retrieved in a laboratory-controlled experiment by measuring their spectral radiance. Granulated bombs of Etnean basalts were melted and the radiant energy from the melting surface was recorded by a portable spectroradiometer in the short wavelength infrared (SWIR) spectral range between 1500 and 2500 nm. The Draping algorithm, an improved algorithm for temperature and emissivity separation, was applied for the first time to SWIR hyperspectral data in order to take into account the non-uniform temperature distribution of the melt surface and, at the same time, solving the two temperatures and the spectral emissivity. The results have been validated by comparing our results with the emissivity measured at a "lava simulator". Basalt spectral emissivity does not vary significantly at magmatic temperature, but shows an absorption feature in the range 2180–2290 nm, an atmospheric window pivotal for the IR remote sensing of active volcanoes.

scholarly journals Spectral Response Assessment of Moss-Dominated Biological Soil Crust Coverage Under Dry and Wet Conditions

2020 ◽  
Vol 12 (7) ◽  
pp. 1158
Author(s):  
Xiang Chen ◽  
Tao Wang ◽  
Shulin Liu ◽  
Fei Peng ◽  
Wenping Kang ◽  
...  
Keyword(s):  
Spectral Response ◽  
Biological Soil Crust ◽  
Hyperspectral Data ◽  
Absorption Feature ◽  
Landsat 8 ◽  
Soil Crust ◽  
Red Edge ◽  
Dry And Wet Conditions ◽  
Low Coverage

Biological soil crusts (BSCs) are a major functional vegetation unit, covering extensive parts of drylands worldwide. Therefore, several multispectral indices have been proposed to map the spatial distribution and coverage of BSCs. BSCs are composed of poikilohydric organisms, the activity of which is sensitive to water availability. However, studies on dry and wet BSCs have seldom considered the mixed coverage gradient that is representative of actual field conditions. In this study, in situ spectral data and photographs of 136 pairs of dry and wet plots were collected to determine the influence of moisture conditions on BSC coverage detection. Then, BSC spectral reflectance and continuum removal (CR) reflectance responses to wetting were analyzed. Finally, the responses of four commonly used indices (i.e., normalized difference vegetation index (NDVI); crust index (CI); biological soil crust index (BSCI); and band depth of absorption feature after CR in the red band, (BD_red)), calculated from in situ hyperspectral data resampled to two multispectral data channels (Landsat-8 and Sentinel-2), were compared in dry and wet conditions. The results indicate that: (i) on average, the estimated BSC coverage using red-green-blue (RGB) images is 14.98% higher in wet than in dry conditions (P < 0.001); (ii) CR reflectance features of wet BSCs are more obvious than those of dry BSCs in both red and red-edge bands; and (iii) NDVI, CI, and BSCI for BSC coverage of 0%–60% under dry and wet conditions are close to those of dry and wet bare sand, respectively. NDVI and BD_red cannot separate dead wood and BSC with low coverage. This study demonstrates that low-coverage moss-dominated BSC is not easily detected by the four indices. In the future, remote-sensing data obtained during the rainy season with red and red-edge bands should be considered to detect BSCs.

scholarly journals Hyperspectral analysis of clay minerals

2014 ◽  
Vol XL-8 ◽  
pp. 443-446 ◽  
Author(s):  
G. Janaki Rama Suresh ◽  
K. Sreenivas ◽  
R. Sivasamy
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Spectral Response ◽  
Chemical Properties ◽  
Xrd Analysis ◽  
Soil Samples ◽  
Hyperspectral Data ◽  
Absorption Feature ◽  
Spectral Angle Mapper ◽  
Feature Parameters

A study was carried out by collecting soil samples from parts of Gwalior and Shivpuri district, Madhya Pradesh in order to assess the dominant clay mineral of these soils using hyperspectral data, as 0.4 to 2.5 μm spectral range provides abundant and unique information about many important earth-surface minerals. Understanding the spectral response along with the soil chemical properties can provide important clues for retrieval of mineralogical soil properties. The soil samples were collected based on stratified random sampling approach and dominant clay minerals were identified through XRD analysis. The absorption feature parameters like depth, width, area and asymmetry of the absorption peaks were derived from spectral profile of soil samples through DISPEC tool. The derived absorption feature parameters were used as inputs for modelling the dominant soil clay mineral present in the unknown samples using Random forest approach which resulted in kappa accuracy of 0.795. Besides, an attempt was made to classify the Hyperion data using Spectral Angle Mapper (SAM) algorithm with an overall accuracy of 68.43 %. Results showed that kaolinite was the dominant mineral present in the soils followed by montmorillonite in the study area.

UAS-based hyperspectral and magnetic mineral exploration targeting Ni-PGE mineralization on Northern Disko Island, West Greenland.

2020 ◽  
Author(s):  
Robert Jackisch ◽  
Robert Zimmermann ◽  
Björn H. Heincke ◽  
Arto Karinen ◽  
Heikki Salmirinne ◽  
...  
Keyword(s):  
Mineral Exploration ◽  
Flood Basalt ◽  
Hyperspectral Data ◽  
Magnetic Data ◽  
Absorption Feature ◽  
Unmanned Aerial Systems ◽  
Geologic Mapping ◽  
West Greenland ◽  
First Results ◽  
First Vertical Derivative

&lt;p&gt;Geologic mapping in arctic regions faces demanding challenges, from accessibility to weather, light and infrastructure conditions. Field expeditions need to cover substantial area, and mostly are supported by satellite and airborne data. While named methods offer large-scaled insights, they often lack the required resolution for precise ground investigations. The rise of unmanned aerial systems (UAS) as new state-of-the-art platform in geoscience provides the means needed to close that scale gap.&lt;/p&gt;&lt;p&gt;Fieldwork within the frame of the EIT project MULSEDRO focused on the Paleocene flood basalt province of Disko Island (West Greenland). On the example of the Qullissat area, we demonstrate how UAS can bring new insights into strategies for magmatic Ni-PGE exploration in the area. Mineralization is associated to basalt sills of the Asuk Member, emplaced locally in coal-bearing cretaceous sandstones. &amp;#160;We conducted photogrammetric outcrop modelling, interpretation of orthoimagery, multi- and hyperspectral based lithological classification and analysis of magnetic data. While magnetics give the location, orientation and subsurface extension of the basaltic sills, spectral imaging, in particular with focus on the iron absorption feature, reveals mineral proxies due to sulphide weathering. A total of 216 line-km for magnetics and 18.5 km&lt;sup&gt;2&lt;/sup&gt; of multi- and hyperspectral data was covered.&lt;/p&gt;&lt;p&gt;First results show that integration of drone-borne spectroscopic and magnetic data highlights potential local mineralization. Based on our results, possible indications for mineralization are linear features in the first vertical derivative of the magnetic data and specific iron absorptions in the spectral data. Resulting maps are validated using handheld spectroscopy, ground magnetics, susceptibility measurements, combined with geochemistry and mineralogy of rock samples examined in the laboratory. Conclusively, the study solidifies UAS as highly valuable tool for exploration.&lt;/p&gt;

scholarly journals Estimation of chlorophyll fluorescence under natural illumination from hyperspectral data

2001 ◽  
Vol 3 (4) ◽  
pp. 321-327 ◽  
Author(s):  
Pablo J Zarco-Tejada ◽  
John R Miller ◽  
Gina H Mohammed ◽  
Thomas L Noland ◽  
Paul H Sampson
Keyword(s):  
Chlorophyll Fluorescence ◽  
Hyperspectral Data ◽  
Natural Illumination

The Eclipsing Binary WX Eridani

1979 ◽  
Vol 46 ◽  
pp. 385
Author(s):  
M.B.K. Sarma ◽  
K.D. Abhankar
Keyword(s):  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Primary Component ◽  
Light Curves ◽  
Absorption Feature ◽  
Primary Star ◽  
Eclipsing Binary ◽  
The Times ◽  
Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

Sign in / Sign up

Export Citation Format

Share Document