scholarly journals Spatial Sharpening of KOMPSAT-3A MIR Images Using Optimal Scaling Factor

2020 ◽  
Vol 12 (22) ◽  
pp. 3772
Author(s):  
Kwan-Young Oh ◽  
Hyung-Sup Jung ◽  
Sung-Hwan Park ◽  
Kwang-Jae Lee
Keyword(s):  
Spectral Resolution ◽  
Visual Analysis ◽  
Spatial Information ◽  
Optimal Scaling ◽  
Scaling Factor ◽  
High Spectral Resolution ◽  
Qualitative Assessment ◽  
Dimensional Synthesis ◽  
The One ◽  
Comparison Of The Results

This paper present efficient methods for merging KOMPSAT-3A (Korea Multi-Purpose Satellite) medium wave Infrared (MIR) and panchromatic (PAN) images. Spatial sharpening techniques have been developed to create an image with both high spatial and high spectral resolution by combining the desired qualities of a PAN image with high spatial and low spectral resolution and an MS/MIR image with low spatial and high spectral resolution. The proposed methods can extract an optimal scaling factor, and uses the tactics of appropriately controlling the balance between the spatial and spectral resolutions. KOMPSAT-3A PAN and MIR images were used to test and evaluate the performance of the proposed methods. A qualitative assessment were performed using the image quality index (Q4), the cross correlation index (CC) and the relative global dimensional synthesis error (Spectral/Spatial ERGAS). These tests indicate that the proposed methods preserve the spectral and spatial characteristics of the original MIR and PAN images. Visual analysis reveals that the spectral and spatial information derived from the proposed methods were well retained in the test images. A comparison of the results of the proposed methods with those obtained from applying existing ones such as the Multi Sensor Fusion (MSF) technique or the Guide Filter Based Fusion (GF) show the efficiency of the new fusion process to be superior to the one of the others. The results showed a significant improvement in fusion capability for KOMPSAT-3A MIR imagery.

scholarly journals Hyperspectral and Multispectral Remote Sensing Image Fusion Based on Endmember Spatial Information

2020 ◽  
Vol 12 (6) ◽  
pp. 1009
Author(s):  
Xiaoxiao Feng ◽  
Luxiao He ◽  
Qimin Cheng ◽  
Xiaoyi Long ◽  
Yuxin Yuan
Keyword(s):  
Image Fusion ◽  
Spatial Resolution ◽  
Spectral Resolution ◽  
Spatial Information ◽  
Spectral Unmixing ◽  
High Spectral Resolution ◽  
Remote Sensing Image Fusion ◽  
Fusion Methods ◽  
Invariant Regions ◽  
The Difference

Hyperspectral (HS) images usually have high spectral resolution and low spatial resolution (LSR). However, multispectral (MS) images have high spatial resolution (HSR) and low spectral resolution. HS–MS image fusion technology can combine both advantages, which is beneficial for accurate feature classification. Nevertheless, heterogeneous sensors always have temporal differences between LSR-HS and HSR-MS images in the real cases, which means that the classical fusion methods cannot get effective results. For this problem, we present a fusion method via spectral unmixing and image mask. Considering the difference between the two images, we firstly extracted the endmembers and their corresponding positions from the invariant regions of LSR-HS images. Then we can get the endmembers of HSR-MS images based on the theory that HSR-MS images and LSR-HS images are the spectral and spatial degradation from HSR-HS images, respectively. The fusion image is obtained by two result matrices. Series experimental results on simulated and real datasets substantiated the effectiveness of our method both quantitatively and visually.

scholarly journals Study of a High Spectral Resolution Hyperspectral LiDAR in Vegetation Red Edge Parameters Extraction

2019 ◽  
Vol 11 (17) ◽  
pp. 2007 ◽  
Author(s):  
Changhui Jiang ◽  
Yuwei Chen ◽  
Haohao Wu ◽  
Wei Li ◽  
Hui Zhou ◽  
...  
Keyword(s):  
Spectral Range ◽  
Spectral Resolution ◽  
Spatial Information ◽  
Research Direction ◽  
Parameter Extraction ◽  
Tunable Filter ◽  
High Spectral Resolution ◽  
Red Edge ◽  
Parameters Extraction ◽  
Vegetation Parameter

Non-contact and active vegetation or plant parameters extraction using hyperspectral information is a prospective research direction among the remote sensing community. Hyperspectral LiDAR (HSL) is an instrument capable of acquiring spectral and spatial information actively, which could mitigate the environmental illumination influence on the spectral information collection. However, HSL usually has limited spectral resolution and coverage, which is vital for vegetation parameter extraction. In this paper, to broaden the HSL spectral range and increase the spectral resolution, an Acousto-optical Tunable Filter based Hyperspectral LiDAR (AOTF-HSL) with 10 nm spectral resolution, consecutively covering from 500–1000 nm, was designed. The AOTF-HSL was employed and evaluated for vegetation parameters extraction. “Red Edge” parameters of four different plants with green and yellow leaves were extracted in the lab experiments for evaluating the HSL vegetation parameter extraction capacity. The experiments were composed of two parts. Firstly, the first-order derivative of the spectral reflectance was employed to extract the “Red Edge” position (REP), “Red Edge” slope (RES) and “Red Edge” area (REA) of these green and yellow leaves. The results were compared with the referenced value from a standard SVC© HR-1024 spectrometer for validation. Green leaf parameter differences between HSL and SVC results were minor, which supported that notion the HSL was practical for extracting the employed parameter as an active method. Secondly, another two different REP extraction methods, Linear Four-point Interpolation technology (LFPIT) and Linear Extrapolation technology (LET), were utilized for further evaluation of using the AOTF-HSL spectral profile to determine the REP value. The differences between the plant green leaves’ REP results extracted using the three methods were all below 10%, and the some of them were below 1%, which further demonstrated that the spectral data collected from HSL with this spectral range and resolution settings was applicable for “Red Edge” parameters extraction.

A Discussion on the physics of the solar atmosphere - The interpretation of hard and soft x-rays from solar flares

1976 ◽  
Vol 281 (1304) ◽  
pp. 473-490 ◽  
Keyword(s):  
Spectral Resolution ◽  
High Spectral Resolution ◽  
Temperature Structure ◽  
X Rays ◽  
Total Energy Release ◽  
Alternative Source ◽  
X Ray ◽  
Source Mechanisms ◽  
Source Models ◽  
The One

The present status of observations of hard X-ray bursts is reviewed in terms of the light they shed on alternative source models and on general characteristics of electron acceleration in flares. Special attention is given to the requirements of total energy release, and the time scale of its release, into energetic electrons on the basis of the normal bremsstrahlung interpretation of bursts. It is particularly emphasized that, since these electrons may dominate the energy balance in many flares, they provide on the one hand an attractive heating mechanism for the thermal flare but, on the other, put severe demands on acceleration mechanisms. A reassessment of the relative merits of synchrotron and inverse Compton source mechanisms is suggested, along with other possibilities, as an escape from this apparent difficulty. Observational characteristics of soft X-ray flares are cursorily reviewed. The importance of a non-isothermal approach to the physics of the soft X-ray plasma is then illustrated in terms of flare energy flow. It is argued however, that high spectral resolution is not the key to this problem since ill conditioning of the problem prevents useful inference of temperature structure. Instead high resolution imaging with moderate spectral resolution is advocated.

scholarly journals Compressive spectral image fusion via a single aperture high throughput imaging system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hoover Rueda-Chacon ◽  
Fernando Rojas ◽  
Henry Arguello
Keyword(s):  
Image Fusion ◽  
Spectral Resolution ◽  
Spatial Information ◽  
Imaging System ◽  
Research Work ◽  
Visible Spectral Range ◽  
Computational Imaging ◽  
High Spectral Resolution ◽  
Spectral Image ◽  
The Rich

AbstractSpectral image fusion techniques combine the detailed spatial information of a multispectral (MS) image and the rich spectral information of a hyperspectral (HS) image into a high-spatial and high-spectral resolution image. Due to the data deluge entailed by such images, new imaging modalities have exploited their intrinsic correlations in such a way that, a computational algorithm can fuse them from few multiplexed linear projections. The latter has been coined compressive spectral image fusion. State-of-the-art research work have focused mainly on the algorithmic part, simulating instrumentation characteristics and assuming independently registered sensors to conduct compressed MS and HS imaging. In this manuscript, we report on the construction of a unified computational imaging framework that includes a proof-of-concept optical testbed to simultaneously acquire MS and HS compressed projections, and an alternating direction method of multipliers algorithm to reconstruct high-spatial and high-spectral resolution images from the fused compressed measurements. The testbed employs a digital micro-mirror device (DMD) to encode and split the input light towards two compressive imaging arms, which collect MS and HS measurements, respectively. This strategy entails full light throughput sensing since no light is thrown away by the coding process. Further, different resolutions can be dynamically tested by binning the DMD and sensors pixels. Real spectral responses and optical characteristics of the employed equipment are obtained through a per-pixel point spread function calibration approach to enable accurate compressed image fusion performance. The proposed framework is demonstrated through real experiments within the visible spectral range using as few as 5% of the data.

scholarly journals A New Algorithm for the Retrieval of Sun Induced Chlorophyll Fluorescence of Water Bodies Exploiting the Detailed Spectral Shape of Water-Leaving Radiance

2021 ◽  
Vol 13 (2) ◽  
pp. 329
Author(s):  
Carolina Tenjo ◽  
Antonio Ruiz-Verdú ◽  
Shari Van Wittenberghe ◽  
Jesús Delegido ◽  
José Moreno
Keyword(s):  
Chlorophyll Fluorescence ◽  
Spectral Resolution ◽  
Optically Active ◽  
High Spectral Resolution ◽  
Support Vector ◽  
Active Constituents ◽  
Wide Range ◽  
Relative Errors ◽  
The One ◽  
Carbon Productivity

Sun induced chlorophyll fluorescence (SICF) emitted by phytoplankton provides considerable insights into the vital role of the carbon productivity of the earth’s aquatic ecosystems. However, the SICF signal leaving a water body is highly affected by the high spectral variability of its optically active constituents. To disentangle the SICF emission from the water-leaving radiance, a new high spectral resolution retrieval algorithm is presented, which significantly improves the fluorescence line height (FLH) method commonly used so far. The proposed algorithm retrieves the reflectance without SICF contribution by the extrapolation of the reflectance from the adjacent regions. Then, the SICF emission curve is obtained as the difference of the reflectance with SICF, the one actually obtained by any remote sensor (apparent reflectance), and the reflectance without SICF, the one estimated by the algorithm (true reflectance). The algorithm first normalizes the reflectance spectrum at 780 nm, following the similarity index approximation, to minimize the variability due to other optically active constituents different from chlorophyll. Then, the true reflectance is estimated empirically from the normalized reflectance at three wavelengths using a machine learning regression algorithm (MLRA) and a cubic spline fitting adjustment. Two large reflectance databases, representing a wide range of coastal and ocean water components and scattering conditions, were independently simulated with the radiative transfer model HydroLight and used for training and validation of the MLRA fitting strategy. The best results for the high spectral resolution SICF retrieval were obtained using support vector regression, with relative errors lower than 2% for the SICF peak value in 81% of the samples. This represents a significant improvement with respect to the classic FLH algorithm, applied for OLCI bands, for which the relative errors were higher than 40% in 59% of the samples.

scholarly journals A 10-nm Spectral Resolution Hyperspectral LiDAR System Based on an Acousto-Optic Tunable Filter

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1620 ◽  
Author(s):  
Yuwei Chen ◽  
Wei Li ◽  
Juha Hyyppä ◽  
Ning Wang ◽  
Changhui Jiang ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Near Infrared ◽  
Spatial Information ◽  
Tunable Filter ◽  
High Spectral Resolution ◽  
Spectral Information ◽  
Time Dimension ◽  
Lidar System ◽  
Full Spectrum ◽  
Comparison Results

Hyperspectral LiDAR (HSL) technology can obtain spectral and ranging information from targets by processing the recorded waveforms and measuring the time of flight (ToF). With the development of the supercontinuum laser (SCL), it is technically easier to develop an active hyperspectral LiDAR system that can simultaneously collect both spatial information and extensive spectral information from targets. Compared with traditional LiDAR technology, which can only obtain range and intensity information at the selected spectral wavelengths, HSL detection technology has demonstrated its potential and adaptability for various quantitative applications from its spectrally resolved waveforms. However, with most previous HSLs, the collected spectral information is discrete, and such information might be insufficient and restrict the further applicability of the HSLs. In this paper, a tunable HSL technology using an acousto-optic tunable filter (AOTF) as a spectroscopic device was proposed, designed, and tested to address this issue. Both the general range precision and the accuracy of the spectral measurement were evaluated. By tuning the spectroscopic device in the time dimension, the proposed AOTF-HSL could achieve backscattered echo with continuous coverage of the full spectrum of 500–1000 nm, which had the unique characteristics of a continuous spectrum in the visible and near infrared (VNIR) regions with 10 nm spectral resolution. Yellow and green leaves from four plants (aloe, dracaena, balata, and radermachera) were measured using the AOTF-HSL to assess its feasibility in agriculture application. The spectral profiles measured by a standard spectrometer (SVC© HR-1024) were used as a reference for evaluating the measurements of the AOTF-HSL. The difference between the spectral measurements collected from active and passive instruments was minor. The comparison results show that the AOTF-based consecutive and high spectral resolution HSL was effective for this application.

Optical interferometry of High-Mass X-ray Binaries: Resolving wind, disk and jet outflows at sub-milliarcsecond scale

2018 ◽  
Vol 14 (S346) ◽  
pp. 114-122
Author(s):  
Idel Waisberg ◽  
Jason Dexter ◽  
P.-O. Petrucci ◽  
Guillaume Dubus ◽  
Karine Perraut ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Spatial Information ◽  
Angular Size ◽  
Optical Interferometry ◽  
High Spectral Resolution ◽  
High Mass ◽  
Heating Process ◽  
X Ray ◽  
First Time ◽  
X Ray Binaries

AbstractBecause of their small angular size < 1 mas, spatial information on High-mass X-ray binaries (HMXB) has typically been inferred from photometry or spectroscopy. Optical interferometry offers the possibility to spatially resolve such systems, but has been traditionally limited to bright targets or low spectral resolution. The VLTI instrument GRAVITY, working in the near-infrared K band, achieves unprecedented precision in differential interferometric quantities at high spectral resolution, allowing to study HMXBs through the lens of optical interferometry for the first time. We present GRAVITY observations on two X-ray binaries: the microquasar SS 433 and the supergiant HMXB BP Cru. The former is the only known steady super-Eddington accretor in the Galaxy and is in a unique stage of binary evolution, with probable ties to at least part of the ULX population. With GRAVITY, we resolve its massive winds and optical baryonic jets for the first time, finding evidence for powerful equatorial outflows and photoionization as the main heating process along the jets. BP Cru harbors an X-ray pulsar accreting from the wind of its early-blue hypergiant companion Wray 977. The GRAVITY observations resolve the inner parts of the stellar wind and allow probing the influence of the orbiting pulsar on the circumstellar environment.

scholarly journals The potassium absorption on HD189733b and HD209458b

2019 ◽  
Vol 489 (1) ◽  
pp. L37-L41 ◽  
Author(s):  
Engin Keles ◽  
Matthias Mallonn ◽  
Carolina von Essen ◽  
Thorsten A Carroll ◽  
Xanthippi Alexoudi ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
High Spectral Resolution ◽  
Upper Limit ◽  
Potassium Absorption ◽  
The One ◽  
Excess Absorption ◽  
Absorption Level

ABSTRACT In this work, we investigate the potassium excess absorption around 7699 Å of the exoplanets HD189733b and HD209458b. For this purpose, we used high-spectral resolution transit observations acquired with the 2 × 8.4 m Large Binocular Telescope (LBT) and the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI). For a bandwidth of 0.8 Å, we present a detection >7σ with an absorption level of 0.18 per cent for HD189733b. Applying the same analysis to HD209458b, we can set 3σ upper limit of 0.09 per cent, even though we do not detect a K-excess absorption. The investigation suggests that the K feature is less present in the atmosphere of HD209458b than in the one of HD189733b. This comparison confirms previous claims that the atmospheres of these two planets must have fundamentally different properties.

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