Showing papers in "Remote Sensing in 1998"
TL;DR: In this paper, a new robust approach (in a statistical sense), approach (RAT) to the use of NOAA/AVHRR observations is proposed and its successful application to different environmental emergencies illustrated also in expectation of next generation of satellite sounders devoted or usable for environmental monitoring purposes.
Abstract: Many algorithms and data analysis techniques have been proposed up to now which make use of satellite observations within atmospheric widows mainly for clouds and surface parameters studies and for environmental monitoring applications. Quite all these algorithms are difficult to extend to different geographical, seasonal conditions, having generally poor performances and uncertain reliability especially when applied in environmental risk prevision, monitoring and/or mitigation. In this paper a new, robust (in a statistical sense), approach (RAT) to the use of NOAA/AVHRR observations is proposed and its successful application to different environmental emergencies illustrated also in expectation of next generation of satellite sounders devoted or usable for environmental monitoring purposes.
153 citations
TL;DR: It is shown that spatially adaptive statistical filters yield better noise reduction and preservation of structures than wavelet- based methods, but that the latter have certain advantages compared to statistical filters which are not spatially adapted.
Abstract: The wavelet transform has become a very popular tool in signal and image processing. Over the last few years, several authors have proposed wavelet-based filters for speckle reduction in SAR*images, and the results are generally reported to be superior to those obtained with traditional statistical speckle filters. In this paper we give a thorough experimental comparison of representative filters from both categories. We show that spatially adaptive statistical filters yield better noise reduction and preservation of structures than wavelet- based methods, but that the latter have certain advantages compared to statistical filters which are not spatially adaptive.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
60 citations
TL;DR: In this article, the spectral radiance of the environment can be measured with a Fourier transform IR (FTIR) spectrometer and the brightness temperature is computed with the inverse function of Planck's radiation law.
Abstract: Passive remote sensing with a Fourier transform IR (FTIR) spectrometer allows the detection and identification of pollutant clouds in the atmosphere. In this work the measurement technique and a data analysis method that does not require a previously measured background spectrum are described. Recent experimental results obtained with anew high sensitive FTIR remote sensor are presented. Many situations do not allow the measurement of a background spectrum prior to the measurement of pollutants in order to perform background removal. After a radiometric calibration of the FTIR spectrometer with IR reference sources the spectral radiance of the environment can be measured. With the inverse function of Planck's radiation law the brightness temperature is computed. The temperature spectrum has a constant baseline for many natural materials that serve as the background in field measurements because their emittance is high and almost constant in the spectral range 800-1200 cm-2. The influence of environmental and instrumental parameters on the sensitivity of the method are discussed. Experimental results are presented to illustrate the enhancement of the signal to noise ratio that can be achieved by the alignment of the spectrometer to backgrounds with a high temperature difference to the environment.
55 citations
TL;DR: Out of the three methods compared, respectively based on high-pass filtering (HPF), wavelet transform (WT), and generalized Laplacian pyramid (GLP), the latter two are far more efficient than the former, thus establishing the advantages for data fusion of a formally multiresolution analysis.
Abstract: This paper reports about a quantitative evaluation of pyramid- based schemes performing a feature-based fusion of data from multispectral and panchromatic imaging sensors having different ground resolutions. A critical point is performances evaluation of image data fusion. A set of quantitative parameters has been recently proposed. Both visual quality, regarded as contrast, presence of fine details, and absence of impairments and artifacts (e.g., blur, ringing), and spectral fidelity (i.e., preservation of spectral signatures) are concerned and embodied in the measurements. The aim of the present work is to provide a comprehensive performance comparison on SPOT data among three feature-based schemes for image fusion, as well as on a specific case study on which multisensor observations were available. Out of the three methods compared, respectively based on high-pass filtering (HPF), wavelet transform (WT), and generalized Laplacian pyramid (GLP), the latter two are far more efficient than the former, thus establishing the advantages for data fusion of a formally multiresolution analysis.
52 citations
TL;DR: The Moon is the only natural object outside the Earth's atmosphere that is within the dynamic range of most imaging instruments on Earth-orbiting spacecraft and the excellent photometric stability of the Lunar surface will allow its use as a long-term instrument calibration source once the dependence of Lunar spectral radiance on phase and libration angles are well characterized as discussed by the authors.
Abstract: The Moon is the only natural object outside the Earth's atmosphere that is within the dynamic range of most imaging instruments on Earth-orbiting spacecraft. The excellent photometric stability of the Lunar surface will allow its use as a long-term instrument calibration source once the dependence of Lunar spectral radiance on phase and libration angles are well characterized. A program to provide this characterization is underway. Observations are being made in 23 bands within 350 - 950 nm, 7 of which correspond closely with spacecraft instrument bands. Observations in nine bands within 950 - 2500 nm began recently. Although at this time the absolute Lunar radiance model is preliminary and uncertainties are larger than most instrument calibration goals, changes in spacecraft instrument sensitivity can be precisely monitored and absolute calibration can be applied retroactively as the accuracy of the Lunar spectral radiance model improves. Several space-based imaging systems have already begun using the Moon for calibration and the EOS AM-1 platform will make periodic attitude maneuvers for Lunar and space calibration.
39 citations
TL;DR: Two different approaches -- watershed thresholding and basin dynamics -- are compared and a new algorithm for the computation of edge dynamics is proposed that brings improvement on ERS-1 images of an agricultural zone.
Abstract: The presence of speckle, which may be modeled as a strong multiplicative noise, makes the segmentation of synthetic aperture radar (SAR) images very difficult. The usual gradient operators yield poor results, but robust operators have been developed specifically for this kind of images. From the edge strength map ('gradient image') created by such an operator, closed skeleton boundaries running through local maxima must be extracted. This can be achieved with the watershed algorithm. However, to reduce the number of false edges, the algorithm must be made less sensitive to speckle. In this article, we compare two different approaches -- watershed thresholding and basin dynamics -- and propose a new algorithm for the computation of edge dynamics. The improvement brought by basin and edge dynamics is illustrated on ERS-1 images of an agricultural zone.
36 citations
TL;DR: The Global Ozone Monitoring Experiment (GOME) on board the ERS-2 satellite is an across-track nadir-viewing spectrometer which measures solar light reflected from the Earth's atmosphere and surface in the UV visible as discussed by the authors.
Abstract: The Global Ozone Monitoring Experiment (GOME) on board the ERS-2 satellite is an across-track nadir-viewing spectrometerwhich measures solar light reflected from the Earth's atmosphere and surface in the UV visible. The cloud retrieval algorithmpresented here combines spectral threshold tests on GOME's broad-band radiances ('-450 nm spectral resolution) with thefitting of reflectances to GOME's moderately high resolution spectra (0.4 nm) in and around the 02 A band to retrieve cloud-cover fraction, cloud-top height and cloud optical thickness. The algorithm utilizes the latest 02 spectroscopic data and featuresdynamical updating procedures to provide global threshold sets of GOME reflectances. Auxiliary information is obtained fromGOME measurements of the Ring effect and the degree of polarization of the Earth's radiation field.Keywords: Cloud detection, cloud retrieval, satellite remote sensing, GOME 1. INTRODUCTION Satellite instruments measuring atmospheric change in the UV, visible and infrared spectral range are strongly influenced by thepresence of clouds in Earth's atmosphere. Failure to account for this presence can result in large errors in the interpretation ofmeasurement data. Reliable cloud detection techniques are therefore crucial for monitoring the Earth's atmosphere from spacein nadir viewing mode.The European Space Agency's (ESA) Global Ozone Monitoring Experiment is an ESA core instrument on board the secondEuropean Remote Sensing (ERS-2) satellite.1 GOME measures reflected and back scattered radiation from 238 to 794 nm atmoderately high resolution (0.2 nm in the ultraviolet and 0.4 nm in the visible and near infrared). The variable swath width ofthe across-track scan provides ground footprints from 40x40 km2 to 40x 320 km2. The largest swath width, which is obtainedin the standard mode of operation, provides full global coverage in three days. A summary of the characteristics of GOME's
36 citations
TL;DR: In a carefully controlled laboratory experiment, the limitations and applicability of two of the methods (a linear and a non- linear one) are compared, in the context of unmixing an intimate mixture.
Abstract: There are two major approaches in spectral unmixing: linear and non-linear ones They are appropriate for different types of mixture, namely checkerboard mixtures and intimate mixtures The two approaches are briefly reviewed Then in a carefully controlled laboratory experiment, the limitations and applicability of two of the methods (a linear and a non- linear one) are compared, in the context of unmixing an intimate mixture© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only
32 citations
TL;DR: An airborne X and L-band Synthetic Aperture Radar system was developed by the joint project of Communication Research Laboratory and National Space Development Agency of Japan from 1993 to 1996 and installed on the airplane, Gulfstream II.
Abstract: An airborne X and L-band Synthetic Aperture Radar system was developed by the joint project of Communication Research Laboratory and National Space Development Agency of Japan from 1993 to 1996 It is installed on the airplane, Gulfstream II The resolution is 15 m/30 m (for X/L-band) in both azimuth and range direction The both SAR are operated with polarimeter capability The X-band SAR has cross-track interferometry function In this report we describe our SAR system, ground processing system and the performance of our system Furthermore we will discuss motion compensation and interferogram quality© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only
26 citations
TL;DR: In this article, the results from the initial nine lunar measurements by SeaWiFS, extending to July 10, 1998, showed changes in the sensitivities of Sea-WiFS bands one through five (412 to 555 nm) to be very small over the eight month interval.
Abstract: Measurements of the lunar surface in the visible and near infrared wavelength regions provide a new and intriguing method of determining changes in the sensitivities of Earth observing radiometers. Lunar measurements are part of the calibration strategy for the instruments in the Earth Observing System (EOS) and part of the calibration strategy for the Sea Viewing Wide Field of View Sensor (SeaWiFS). SeaWiFS was launched on August 1, 1997. The first SeaWiFS images of the Earth were taken on September 4, 1997, and the first lunar measurements were made on November 14, 1997. We describe the results from the initial nine lunar measurements by SeaWiFS, extending to July 10, 1998. The time series for the lunar images show changes in the sensitivities of SeaWiFS bands one through five (412 to 555 nm) to be very small over the eight month interval. For band 6 (670 nm), the decrease in sensitivity over seven months is 1/2%. For bands 7 and 8 (765 and 865 nm), the decreases are 11/2% and 5% respectively. These changes, with reduced scatter in the results, are also found in the band ratios. The instrument changes can be seen in the SeaWiFS data products. Using the lunar time series, plus data from diffuser and ocean surface measurements, a time-dependent correction for the changes in the sensitivities of bands 6, 7, and 8 has been applied in the SeaWiFS data processing algorithm.
26 citations
TL;DR: GOME is the first satellite instrument with the capability to retrieve height-resolved ozone densities in both stratosphere and troposphere as mentioned in this paper, which enables the derivation of accurate ozone profiles.
Abstract: GOME is the first satellite instrument with the possibility to retrieve height-resolved ozone densities in both stratosphere and troposphere. The high accuracy and spectral resolution of the GOME spectrometer in the range of 240-790 nm combined with sophisticated retrieval algorithms enables the derivation of accurate ozone profiles. This paper discusses in detail the retrieval procedure of ozone profiles from the GOME observations. The resulting profiles and their calculated errors are discussed and compared to local ozone profiles form ozone sonde measurements.
TL;DR: Based on the DEM previously computed, geometric and colorimetric criteria are used for the fusion of parallel regions, for the detection of symmetrical regions in the 3D object space and for the reconstruction of roof buildings.
Abstract: We describe a new method for the detection and reconstruction of building in dense urban areas using high resolution aerial images. Our approach begins with the generation of a dense digital elevation model (DEM). A sparse disparity map is densified using a region-based segmentation of the left aerial image: each detected region is tested to be planar in the disparity map. A strategy is proposed to optimize the generation of these planar surfaces taking into account the noise present in the sparse disparity map and the robustness and complexity of different algorithms for planar approximation. The second step of our approach deals with the generation of building hypotheses. Based on the DEM previously computed, geometric and colorimetric criteria are used for the fusion of parallel regions, for the detection of symmetrical regions in the 3D object space and for the reconstruction of roof buildings. Experimental results are presented on a scene in the suburb of Bruxelles with color images at the resolution of 10 cm/pixel.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this paper, the performance, imperfections and properties of each component of the measurement chain are studied, and a part of the work is devoted to characterize precisely the source, and particularly the spatial variability of the irradiance at the target level, the temporal stability and the spectral profile of the lamp.
Abstract: The bi-directional reflectance distribution function (BRDF) plays a major role to evaluate or analyze signals reflected by Earth in the solar spectrum. A BRDF measurement device that covers a large spectral and directional domain was recently developed by ONERA/DOTA. It was designed to allow both laboratory and outside measurements. Its main characteristics are a spectral domain: 0.42-0.95 micrometers ; a geometrical domain: 0-60 degrees for zenith angle, 0-180 degrees for azimuth; a maximum target size for nadir measurements: 22 cm. For a given zenith angle of the source, the BRDF device needs about seven minutes to take measurements for a viewing zenith angle varying from 0-60 degrees and relative azimuth angle varying from 0-180 degrees. The performances, imperfections and properties of each component of the measurement chain are studied. A part of the work was devoted to characterize precisely the source, and particularly the spatial variability of the irradiance at the target level, the temporal stability and the spectral profile of the lamp. Some of these imperfections are modeled and taken into account in corrections of BRDF measurements. Concerning the sensor, a calibration in wavelength was done. Measurements of bi- directional reflectance of which is well known. A software was developed to convert all the raw data acquired automatically into BRDF values. To illustrate measurements taken by this device, some results are also presented here. They are taken over sand and short grass, for different wavelengths and geometrical conditions.
TL;DR: In this article, the authors used high spectral resolution optical signatures for detecting plant stress related to the vegetation's moisture within the leaf structure and showed potential for being used as the basis for firmware or "silicon strategy" based algorithms in the future.
Abstract: The practical application of current airborne and future satellite or space station based high spectral resolution (hyperspectral) imagery to vegetative canopies (sparse or dense) and resulting derived bio-physical variables will depend upon our ability to rapidly apply scientifically based algorithms. Key to these rapid assessments is the selection of the best or optimal channels or bands for detection of plant stress or dysfunction. Previous work has demonstrated the potential of utilizing high spectral resolution optical signatures for detecting plant stress related to the vegetation's moisture within the leaf structure. Future algorithms and techniques need to discriminate plant species as well as any plant dysfunction or stresses in terms of leaf chemistry or other canopy bio-physical variables in order to improve operational advances in the use of hyperspectral imagery for environmental surveillance, agriculture and earth system science management. Second derivative imagery based upon derivative algorithms and selected bands are presented for AVIRIS imagery of Kennedy Space Center, Cape Canaveral and the Satellite Beach region of central Florida. The algorithms show potential for being used as the basis for firmware or 'silicon strategy' based algorithms in the future.
TL;DR: The SAGE III is the fourth generation of solar occultation instruments designed to measure aerosols and trace gas species in the stratosphere and upper troposphere as mentioned in this paper, and it will be launched aboard a Meteor-3M platform in the summer of 1999 and the International Space Station Alpha in 2001.
Abstract: The SAGE III is the fourth generation of solar occultation instruments designed to measure aerosols and trace gas species in the stratosphere and upper troposphere. It will be launched aboard a Meteor-3M platform in the summer of 1999 and the International Space Station Alpha in 2001. SAGE III preserves the robust characteristics of the SAGE series, including self-calibration and high vertical resolution, and adds new capabilities including a lunar occultation mode. This paper will describe the SAGE III instrument and outline its potential contribution to global change research.
TL;DR: In this paper, the entropy is considered to define a prior and a hyper-parameter is proposed to define the coarseness of the clustering and is data independent, which enables the problem of defining a prior a the number of clusters and an initialization of their centers.
Abstract: The problem of unsupervised clustering of data is formulated using a Bayesian inference. The entropy is considered to define a prior. In clustering problem we have to reduce the complexity of the gray level description. Therefore we minimize the entropy associated with the clustering histogram. This enables us to overcome the problem of defining a priori the number of clusters and an initialization of their centers. Under the assumption of a normal distribution of data the proposed clustering method reduces to a deterministic algorithm (very fast) which appears to be an extension of the standard k-means clustering algorithm. Our model depends on a parameter weighting the prior term and the goodness of fit term. This hyper-parameter allows us to define the coarseness of the clustering and is data independent. Heuristic argument is proposed to estimate this parameter. The new clustering approach was successfully tested on a database of 65 magnetic resonance images and remote sensing images.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: The Phased Array type L-band Synthetic Aperture Radar on the Advanced Land Observing Satellite (ALOS) is considered to be one of the follow-on sensors of JERS-1 SAR and the PALSAR system design is described.
Abstract: The Phased Array type L-band Synthetic Aperture Radar (PALSAR) on the Advanced Land Observing Satellite (ALOS) is considered to be one of the follow-on sensors of JERS-1 SAR. PALSAR is designed to achieve high radiometric performance as well as observation flexibility, in addition to the data continuity of JERS-1. It has a beam steering capability using an active phased array antenna, and a multi-polarization capability. In order to achieve high radiometric performance, the system parameters have been carefully designed, and some internal calibration procedures have been investigated. Based on the current design, PALSAR can acquire the data from 8 to 60 degrees of incidence angle. A noise equivalent backscattering coefficient is from -30 to -25 dB depending on the incidence angle. The required radiometric stability is within 1 dB over one scene. The status of development is currently the Bread Board Model (BBM) phase, and NASDA has manufactured the antenna system and tested it both electronically and mechanically. This paper describes the PALSAR system design as well as some results from BBM development.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: A new method for computing an elevation map from a single SAR image by reconstructing an approximate elevation map of the imaged ground using radarclinometry, which relies on a Lambertian assumption for the backscatter model, which, as experiments have shown, is not particularly accurate.
Abstract: Synthetic aperture radar (SAR) imagery is now well-known as it is actively used in various remote sensing domains such as oceanography, geology, environment surveillance, cartography, etc. In this paper, we describe a new method for computing an elevation map from a single SAR image. Our method begins by reconstructing an approximate elevation map of the imaged ground using radarclinometry. This reconstruction relies on a Lambertian assumption for the backscatter model, which, as our experiments have shown, is not particularly accurate. Therefore, once we have computed the initial estimation, we proceed to estimate a more accurate backscatter model for the imaged ground. After a brief description of the relevant reflection mechanisms, we show that the theoretical considerations are too complex to be completely and accurately modeled. We therefore present two methods for performing the backscatter estimation. The first method is based on empirical results. The second method makes use of the approximate elevation map obtained by radarclinometry. In the latter case, we subsequently compute an improved elevation map using the more accurate backscatter model.
TL;DR: In this article, more than one hundred radiosonde ascents are examined to evaluate the occurrence of anomalous propagation (AP) of microwave radiation at the coastal site of Barcelona (Spain). Temperature and humidity profiles are used to calculate refractivity gradients and to estimate the existence of ducting layers.
Abstract: Several meteorological conditions are known to cause anomalous propagation (AP) of microwave radiation. The effect of AP in weather radar measurements my be important as spurious echoes from distant ground targets may appear as precipitation leading to wrong rainfall estimations. AP may also affect dramatically the quality of clear air radar observations. In this study, more than one hundred radiosonde ascents are examined to evaluate the occurrence of AP at the coastal site of Barcelona (Spain). Temperature and humidity profiles are used to calculate refractivity gradients and to estimate the existence of ducting layers. Ducts represent the worst case of super refraction and within them microwaves travel trapped like in a waveguide. To detect thin AP features a vertical resolution higher than that given by standard operational radiosonde data is desirable. For this reason, radiosonde data recorded every 10 s have been used. Results are compared against standard operational radiosonde analysis revealing a significantly higher number of AP layers. The output of a mesoscale numerical weather prediction model is also used to derive refractivity gradients. The ability of the model to simulate the propagation conditions is overviewed in order to assess the feasibility of an operational diagnostic AP product.
TL;DR: In this article, the authors suggest the development of observation methods based on the optical radar or lidar, which is a precise and versatile tool for the atmospheric correction of marine radiance data sensed from satellite (accuracy better than 10% for typical conditions).
Abstract: Satellite remote sensing of sea color is a powerful instrument to perform oceanic studies. Unfortunately, the present data processing algorithms are not exempt from uncertainties, especially because the marine radiance must be separated from the atmospheric contributions, which typically represent about 80% of the total. In this paper we suggest the development of observation methods based on the optical radar or lidar. In fact, the numerical simulation of a sea-level optical radar demonstrates that, if applied to restricted areas, such system is a precise and versatile tool for the atmospheric correction of marine radiance data sensed from satellite (accuracy better than 10% for typical conditions). Moreover, the lidar is effective even in environments that would be severe for the standard corrective schemes. Finally, the feasibility of a spaceborne system is discussed.
TL;DR: GOMETRAN/SCIATRAN is a radiative transfer forward model developed for retrieval of atmospheric trace gas concentrations, aerosol and cloud parameters, and surface reflectance from the spectral radiance measurements of the SCIAMACHY/ENVISAT-1 and GOME/ERS-2 UV-Vis-NIR multichannel spectrometers.
Abstract: GOMETRAN/SCIATRAN is a radiative transfer forward model developed for retrieval of atmospheric trace gas concentrations, aerosol and cloud parameters, and surface reflectance from the spectral radiance measurements of the SCIAMACHY/ENVISAT-1 and GOME/ERS-2 UV-Vis-NIR multichannel spectrometers For radiative transfer modeling of the line absorptions of O2, H2O, CO2, CH4, N2O, and CO, tow different schemes are under development: an accurate but rather slow line-by-line (LBL) implementation and a significantly faster correlated-k (c-k) distribution scheme The c-k scheme has been matched to the resolution of the instruments, which is channel dependent In spectral regions free of overlapping line-absorbers the multiply scattered radiance calculated with both, the LBL and the c-k scheme, agrees within 1-2 percent Calculations in c-k mode are a factor of 25-800 faster depending on spectral interval Good agreement has been found with the MODTRAN/DISORT radiative transfer model First results concerning a new method are presented indicating that overlapping line-absorbers can be modeled with similar accuracy and speed as single line-absorbers
TL;DR: The next generation of smart sensors to address these new requirements of: low-cost, high bandwidth, miniaturization, ultra low-power and mission environment ruggedness are developed by JPL.
Abstract: Given the current choices of (1) an ever increasing population of large numbers of satellites in low-earth orbit (LEO) constellations for commercial and military global coverage systems, or (2) the alternative of smaller count geosynchronous satellite system constellations in high-earth (HEO), of higher cost and complexity, a number of commercial communications and military operations satellite systems designers are investigating the potential advantages and issues of operating in the mid-earth orbit altitudes (MEO) (between LEO and HEO). At these MEO altitudes both total dose and displacement damage can be traded against the system advantages of fewer satellites required. With growing demand for higher bandwidth communication for real-time earth observing satellite sensor systems, and NASA's interplanetary and deep space virtual unmanned exploration missions in stressing radiation environments, JPL is developing the next generation of smart sensors to address these new requirements of: low-cost, high bandwidth, miniaturization, ultra low-power and mission environment ruggedness. Radiation hardened/tolerant Active Pixel Sensor CMOS imagers that can be adaptively windowed with low power, on-chip control, timing, digital output and provide data-channel efficient on-chip compression, high bandwidth optical communications links are being designed and investigated to reduce size, weight and cost for common optics/hybrid architectures.
TL;DR: A fusion algorithm is presented which consists in implementing different statistical rules for radar or optical images, and a pixel-by-pixel basis classification which requires a preliminary spatial and/or temporal speckle filtering.
Abstract: For the classification of the radar data, several techniques have been developed, which take the statistical properties of the radar distribution into account and use a priori segmentation to have better contextual information. The introduction of synthetic neo-channels, describing the local texture of radar images, improve the classification process. We also test two different processes to minimize the inter- class confusion caused by the speckle noise: a pixel-by-pixel basis classification which requires a preliminary spatial and/or temporal speckle filtering, or a contextual method without filtering. In the case of the multi-source data classification, we present a fusion algorithm which consists in implementing different statistical rules for radar or optical images.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: An integration method of the radar information in multispectral images without disturbing the spectral content is proposed and a new fusion rule performed in the redundant wavelet domain based on the Mahalanobis distance applied on the wavelet coefficients is defined.
Abstract: We propose in this paper an integration method of the radar information in multispectral images without disturbing the spectral content The main problem is to define a fusion rule that allows to take into account the characteristics of these images Also, the main purpose of this paper lies in defining a new fusion rule performed in the redundant wavelet domain This rule is based on the Mahalanobis distance applied on the wavelet coefficients Instead of comparing coefficient-to- coefficient, the distance-to-distance comparison is performed In this case the selected coefficient in the fused image will be the one that presents the large distance This approach is applied to fusing the infrared band of SPOT with, respectively, RADARSAT and ERS images The results show that spectral information is well preserved and there is a better information on the texture and the area roughness© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only
TL;DR: SCIAMACHY (Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY) is a contribution to the ENVISAT-1 satellite, which is to be launched in spring 2000.
Abstract: SCIAMACHY (Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY) is a contribution to the ENVISAT-1 satellite, which is to be launched in spring 2000. The SCIAMACHY instrument is designed to measure sunlight transmitted, reflected and scattered by the Earth's atmosphere or surface. The instrument measures simultaneously from the UV to the NIB spectral spectral region (240 - 2380 nm). Observations are made in alternate nadir and limb viewing geometries and also for solar sunrise and lunar moonrise occultation. Inversion of the SCIAMACHY measurements will provide the following: the amount and distributions of some important trace gases O3, BrO, OClO, ClO, SO2, H2CO, NO2, CO, CO2, CH4, H2O, N2O, p, T, aerosol, and radiation flux profiles, cloud cover and cloud top height. Combination of the near simultaneous limb and nadir observations enables the tropospheric column amounts of O3, NO2, CO, CH4, H2O, N2O, SO2, and H2CO to be detected. SCIAMACHY will provide new insight into the global behavior of the troposphere and the stratosphere.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this article, a multi-resolution approach based on fractal geometry for oil spill detection in ERS SAR images was proposed, which is based on the normalized Laplacian pyramid which provides a band-pass description of the image.
Abstract: SAR images from the ERS satellites have proved to be helpful data for identification of oil spills. Because the presence of oil slicks on sea surface increases the surface tension of sea water, the surface wave motion is significantly depressed. This effect relatively reduces the sea surface roughness, decreases the radar backscattered energy and enables oil slicks to be discernible from the radar image. The use of fractal dimension, which is related to the concept of surface 'roughness,' as a feature for classification, improves the oil spill detection, since enhances texture discrimination with respect to first and second order derivative operators, e.g., DoG and LoG. This paper describes a multi-resolution approach based on fractal geometry for oil spill detection in ERS SAR images. The proposed multi-resolution algorithm is based on the normalized Laplacian pyramid which provides a band-pass description of the image. Thanks to normalization of each layer of the pyramid by its low-pass version, the image noise becomes independent on the image signal, and a reliable estimate of the fractal dimension can be computed from ratio of power spectra at different scales. The experimental results carried out both on synthetic and ERS-1 SAR images prove the effectiveness of the fractal-based approach for the classification of oil spills.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: Fourier transform IR (FTIR) spectroscopy for making non-intrusive measurements of gas turbine exhaust gases and laser induced incandescence for measuring soot content are being evaluated in EU Brite EuRam project AEROJET as mentioned in this paper.
Abstract: Fourier transform IR (FTIR) spectroscopy for making non- intrusive measurements of gas turbine exhaust gases and laser induced incandescence for measuring soot content are being evaluated in EU Brite EuRam project AEROJET. Soot concentrations in modern aero-engine exhausts are very low with mean particle sizes < 100 nm. The standard extractive filter paper soot measurement gives results expressed in terms of SAE smoke number, typically < 10 SAE for modern engines.
TL;DR: In this paper, a generalized soil-adjusted vegetation index (GESAVI) is introduced, which is defined in terms of the soil line parameters (A and B) as: GESAVI equals (NIR-BR-A)/(R + Z), where Z is related to the red reflectance at the cross point between the soil lines and vegetation isolines.
Abstract: Operational monitoring of vegetative cover by remote sensing currently involves the utilization of vegetation indices (VIs), most of them being functions of the reflectance in red (R) and near-infrared (NIR) spectral bands. A generalized soil-adjusted vegetation index (GESAVI), theoretically based on a simple vegetation canopy model, is introduced. It is defined in terms of the soil line parameters (A and B) as: GESAVI equals (NIR-BR-A)/(R + Z), where Z is related to the red reflectance at the cross point between the soil line and vegetation isolines. Z can be considered as a soil adjustment coefficient which let this new index be considered as belonging to the SAVI family. In order to analyze the GESAVI sensitivity to soil brightness and soil color, both high resolution reflectance data from two laboratory experiments and data obtained by applying a radiosity model to simulate heterogeneous vegetation canopy scenes were used. VIs (including GESAVI, NDVI, PVI and SAVI family VIs) were computed and their correlation with LAI for the different soil backgrounds was analyzed. Results confirmed the lower sensitivity of GESAVI to soil background in most of the cases, thus becoming the most efficient index. This good index performance results from the fact that the isolines in the NIR-R plane are neither parallel to the soil line (as required by the PVI) nor convergent at the origin (as required by the NDVI) but they converge somewhere between the origin and infinity in the region of negative values of both NIR and R. This convergence point is not necessarily situated on the bisectrix, as required by other SAVI family indices.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: The MightySat II has been successfully tested and a payload Critical Deign Review was passed as discussed by the authors, and the payload is scheduled to be delivered in April 1999 for integration on to the spacecraft bus.
Abstract: Previous papers have described the concept behind the MightySat II.1 program, the satellite' Fourier Transform imaging spectrometer's optical design, and the design for the hyperspectral imaging payload. Initial qualification testing of the payload has been completed. All component level qualification tests have been finished. The solid block optics, interferometer, camera and telescope where all successfully tested and a payload Critical Deign Review was passed. Early optical testing of the monolithic interferometer has shown that it has the designed spectral resolution of less than 100 cm-1. Bench testing of a custom VME data interface board that operates the sensor in a variety of spatial and spectral resolution modes can transfer data satisfactorily at data rates up to 24.3 Mbytes/sec over a VSB bus to spacecraft solid state memory. Problems in manufacturing the hardened C-40 processors has caused a change to an unhardened version of the C-40 using tantalum foil for protection. This still allows all hyperspectral 'smart' imaging spectrometer demonstrations including a 10:1 data compression technique. The payload is scheduled to be delivered in April 1999 for integration on to the spacecraft bus.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this article, a thermal radiation detector for possible deployment on GERB (Geostationary Earth Radiation Budget) is described, which consists of a linear array of 256 elements, each 60 micrometer square and separated by a 3-micrometer gap.
Abstract: Described is thermal radiation detector conceived for possible deployment on GERB (Geostationary Earth Radiation Budget). It consists of a linear array of 256 elements, each 60 micrometer square and separated by a 3-micrometer gap. Each element is the active junction of a single-junction-pair zinc- antimonide/platinum thermopile. The reference junction is mounted on an isothermal substrate, and the active junction is thermally isolated from the substrate by a thin layer of parylene. The detector is mounted on one wall of a wedge- shaped, mirrored cavity intended to increase the effective absorptivity and improve the spectral flatness of the detector through multiple reflections. A dynamic opto-electrothermal model of the detector/cavity combination has been formulated in order to facilitate its optimal design. The optical part of the model is based on a Monte-Carlo ray trace that takes into account diffraction at the entrance slit as well as the diffuse and specular components of reflectivity of the cavity surfaces. Heat absorption and diffusion through the thermopile structure has been modeled using the finite element method. The model has been used to validate a method for eliminating optical cross-talk among elements of the array through post- processing of data.