1,728 research outputs found
HIRIS (High-Resolution Imaging Spectrometer: Science opportunities for the 1990s. Earth observing system. Volume 2C: Instrument panel report
The high-resolution imaging spectrometer (HIRIS) is an Earth Observing System (EOS) sensor developed for high spatial and spectral resolution. It can acquire more information in the 0.4 to 2.5 micrometer spectral region than any other sensor yet envisioned. Its capability for critical sampling at high spatial resolution makes it an ideal complement to the MODIS (moderate-resolution imaging spectrometer) and HMMR (high-resolution multifrequency microwave radiometer), lower resolution sensors designed for repetitive coverage. With HIRIS it is possible to observe transient processes in a multistage remote sensing strategy for Earth observations on a global scale. The objectives, science requirements, and current sensor design of the HIRIS are discussed along with the synergism of the sensor with other EOS instruments and data handling and processing requirements
Vicarious Methodologies to Assess and Improve the Quality of the Optical Remote Sensing Images: A Critical Review
Over the past decade, number of optical Earth observing satellites performing remote sensing has increased substantially, dramatically increasing the capability to monitor the Earth. The quantity of remote sensing satellite increase is primarily driven by improved technology, miniaturization of components, reduced manufacturing, and launch cost. These satellites often lack on-board calibrators that a large satellite utilizes to ensure high quality (e.g., radiometric, geometric, spatial quality, etc.) scientific measurement. To address this issue, this work presents “best” vicarious image quality assessment and improvement techniques for those kinds of optical satellites which lacks on-board calibration system. In this article, image quality categories have been explored, and essential quality parameters (e.g., absolute and relative calibration, aliasing, etc.) have been identified. For each of the parameters, appropriate characterization methods are identified along with its specifications or requirements. In cases of multiple methods, recommendation has been made based-on the strengths and weaknesses of each method. Furthermore, processing steps have been presented, including examples. Essentially, this paper provides a comprehensive study of the criteria that needs to be assessed to evaluate remote sensing satellite data quality, and best vicarious methodologies to evaluate identified quality parameters such as coherent noise, ground sample distance, etc
Atmospheric Correction of Landsat ETM+ Land Surface Imagery—Part I: Methods
To extract quantitative information from the Enhanced
Thematic Mapper-Plus (ETM+) imagery accurately,
atmospheric correction is a necessary step. After reviewing historical
development of atmospheric correction of Landsat thematic
mapper (TM) imagery, we present a new algorithm that can effectively
estimate the spatial distribution of atmospheric aerosols and
retrieve surface reflectance from ETM+ imagery under general
atmospheric and surface conditions. This algorithm is therefore
suitable for operational applications. A new formula that accounts
for adjacency effects is also presented. Several examples are given
to demonstrate that this new algorithm works very well under a
variety of atmospheric and surface conditions. The companion
paper will validate this method using ground measurements,
and illustrate the improvements of several applications due to
atmospheric correction.This work was supported in part by the U.S. National Aeronautics and Space Administration
(NASA), Washington, DC, under Grant NAG5-6459
Impact of land use change on urban surface temperature and urban green space planning; case study of the island of Bali, Indonesia
Land use and surface temperature were monitored from 1995 to 2013 to examine green space development in Bali using Landsat and ASTER imageries. Urban areas were formed by conversion of vegetation and paddy fields. Heat islands with surface temperature of over 29 ÂşC were found and influenced by urban area types. High priority, low priority and not a priority zones for green space were resulted by weighted overlay of LST, NDVI and urban area types
Examining Urban Heat Island Effect and Its Public Health Implications with Remotely Sensed Data
The Urban heat island (UHI) as a byproduct of urbanization has long been studied utilizing remote sensing technologies. However, issues remain to be addressed. Land surface temperature (LST) as the indicator of surface UHI can be retrieved from remotely sensed data, but its accuracy is limited as existing studies neglect the neighboring effect. Further, while LST serves well as an indicator of surface thermal condition, it lacks the ability to reveal human heat stress, which is an environmental hazard that can seriously affect productivity, health or even survival of individuals. Although human heat stress has long been studied and can be quantified by many heat stress indices, it has never been explored across continuous spaces. Aiming to address these issues, the objectives of this research include: (1) taking into account the neighboring effect during LST retrieval using a moving window method; (2) revealing human heat stress with remotely sensed data; and (3) exploring the relationship between heat stress and land cover composition and configuration. My results indicate that the accuracy of LST estimation is improved when neighboring effect is considered. Discomfort index (DI) as an indicator of human heat stress can be retrieved from remotely sensed data, and its spatial distribution and relationship with land cover composition is largely affected by relative humidity. Spatial configuration of different land covers has an impact on DI, which may provide insights for policy makers and urban designers on mitigating hazardous environmental effect brought by urbanization
LANDSAT-D investigations in snow hydrology
Work undertaken during the contract and its results are described. Many of the results from this investigation are available in journal or conference proceedings literature - published, accepted for publication, or submitted for publication. For these the reference and the abstract are given. Those results that have not yet been submitted separately for publication are described in detail. Accomplishments during the contract period are summarized as follows: (1) analysis of the snow reflectance characteristics of the LANDSAT Thematic Mapper, including spectral suitability, dynamic range, and spectral resolution; (2) development of a variety of atmospheric models for use with LANDSAT Thematic Mapper data. These include a simple but fast two-stream approximation for inhomogeneous atmospheres over irregular surfaces, and a doubling model for calculation of the angular distribution of spectral radiance at any level in an plane-parallel atmosphere; (3) incorporation of digital elevation data into the atmospheric models and into the analysis of the satellite data; and (4) textural analysis of the spatial distribution of snow cover
a Berlin case study
Durch den Prozess der Urbanisierung verändert die Menschheit die Erdoberfläche in großem Ausmaß und auf unwiederbringliche Weise. Die optische Fernerkundung ist eine Art der Erdbeobachtung, die das Verständnis dieses dynamischen Prozesses und seiner Auswirkungen erweitern kann. Die vorliegende Arbeit untersucht, inwiefern hyperspektrale Daten Informationen über Versiegelung liefern können, die der integrierten Analyse urbaner Mensch-Umwelt-Beziehungen dienen. Hierzu wird die Verarbeitungskette von Vorverarbeitung der Rohdaten bis zur Erstellung referenzierter Karten zu Landbedeckung und Versiegelung am Beispiel von Hyperspectral Mapper Daten von Berlin ganzheitlich untersucht. Die traditionelle Verarbeitungskette wird mehrmals erweitert bzw. abgewandelt. So wird die radiometrische Vorverarbeitung um die Normalisierung von Helligkeitsgradienten erweitert, welche durch die direktionellen Reflexionseigenschaften urbaner Oberflächen entstehen. Die Klassifikation in fünf spektral komplexe Landnutzungsklassen wird mit Support Vector Maschinen ohne zusätzliche Merkmalsextraktion oder Differenzierung von Subklassen durchgeführt...thesi
Surface Reflectance of Mars Observed by CRISM-MRO: 1. Multi-angle Approach for Retrieval of Surface Reflectance from CRISM Observations (mars-reco)
This article addresses the correction for aerosol effects in near-simultaneous multiangle observations acquired by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard the Mars Reconnaissance Orbiter. In the targeted mode, CRISM senses the surface of Mars using 11 viewing angles, which allow it to provide unique information on the scattering properties of surface materials. In order to retrieve these data, however, appropriate strategies must be used to compensate the signal sensed by CRISM for aerosol contribution. This correction is particularly challenging as the photometric curve of these suspended particles is often correlated with the also anisotropic photometric curve of materials at the surface. This article puts forward an innovative radiative transfer based method named Multi-angle Approach for Retrieval of Surface Reflectance from CRISM Observations (MARS-ReCO). The proposed method retrieves photometric curves of surface materials in reflectance units after removing aerosol contribution. MARS-ReCO represents a substantial improvement regarding previous techniques as it takes into consideration the anisotropy of the surface, thus providing more realistic surface products. Furthermore, MARS-ReCO is fast and provides error bars on the retrieved surface reflectance. The validity and accuracy of MARS-ReCO is explored in a sensitivity analysis based on realistic synthetic data. According to experiments, MARS-ReCO provides accurate results (up to 10 reflectance error) under favorable acquisition conditions. In the companion article, photometric properties of Martian materials are retrieved using MARS-ReCO and validated using in situ measurements acquired during the Mars Exploration Rovers mission
An Analysis of the Radiometric Quality of Small Unmanned Aircraft System Imagery
In recent years, significant advancements have been made in both sensor technology and small Unmanned Aircraft Systems (sUAS). Improved sensor technology has provided users with cheaper, lighter, and higher resolution imaging tools, while new sUAS platforms have become cheaper, more stable and easier to navigate both manually and programmatically. These enhancements have provided remote sensing solutions for both commercial and research applications that were previously unachievable. However, this has provided non-scientific practitioners with access to technology and techniques previously only available to remote sensing professionals, sometimes leading to improper diagnoses and results. The work accomplished in this dissertation demonstrates the impact of proper calibration and reflectance correction on the radiometric quality of sUAS imagery.
The first part of this research conducts an in-depth investigation into a proposed technique for radiance-to-reflectance conversion. Previous techniques utilized reflectance conversion panels in-scene, which, while providing accurate results, required extensive time in the field to position the panels as well as measure them. We have positioned sensors on board the sUAS to record the downwelling irradiance which then can be used to produce reflectance imagery without the use of these reflectance conversion panels.
The second part of this research characterizes and calibrates a MicaSense RedEdge-3, a multispectral imaging sensor. This particular sensor comes pre-loaded with metadata values, which are never recalibrated, for dark level bias, vignette and row-gradient correction and radiometric calibration. This characterization and calibration studies were accomplished to demonstrate the importance of recalibration of any sensors over a period of time. In addition, an error propagation was performed to detect the highest contributors of error in the production of radiance and reflectance imagery.
Finally, a study of the inherent reflectance variability of vegetation was performed. In other words, this study attempts to determine how accurate the digital count to radiance calibration and the radiance to reflectance conversion has to be. Can we lower our accuracy standards for radiance and reflectance imagery, because the target itself is too variable to measure? For this study, six Coneflower plants were analyzed, as a surrogate for other cash crops, under different illumination conditions, at different times of the day, and at different ground sample distances (GSDs)
Recommended from our members
Surface reflectance characteristics of Langjökull, Iceland
ATM, ETM+ and MODIS radiance data collected for the surface of Langjokull during August 2007.
Radiance data from the three different instruments was then converted to surface broadband
albedo using a number of different methods. The differences between the methods used to derive
the surface albedo were then compared, followed by an analysis of the impact of spatial
resolution and sample size on the differences between the derived surface albedo. Analysis of the
different datasets combined with transect sample analyses of the derived surface albedos
indicated that the most precise methods of deriving albedo from the ATM and ETM+ instruments
was through the use of FLAASH for the ATM and dark pixel atmospheric correction or 6S
atmospheric correction for the ETM+. These first analyses also indicated that the MODIS data was
broadly in agreement with these two datasets. However, analysis of the differences between the
different spatial resolution datasets across the three different spatial extents revealed a number
of differences between the datasets. At the smallest scale the lower resolution datasets were
shown to contain a bias towards representing certain areas in individual pixels. Consequently, the
correlation between the datasets was reduced across greater sample sizes. Moreover, this bias
was shown to prevent the ETM+ and MODIS imagery from averaging highly variable surfaces. The
result of these measurement characteristics was for the low resolution instruments to
overestimate the albedo value of snow in the accumulation area, greatly underestimate the
albedo in the firn zone and struggle to capture the spatial variability in the ablation zone. The
implications of these characteristics for lower resolution data have consequently been outlined,
with the extent of the differences between both the low resolution datasets and the ATM dataset,
indicating that where possible ETM+ imagery should be used to monitor surface albedo
characteristics as it was the most closely correlated with the ATM data
- …