By Topic

Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of

Issue 4 • Date Dec. 2011

Filter Results

Displaying Results 1 - 25 of 38
  • [Front cover]

    Page(s): C1
    Save to Project icon | Request Permissions | PDF file iconPDF (506 KB)  
    Freely Available from IEEE
  • IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing publication information

    Page(s): C2
    Save to Project icon | Request Permissions | PDF file iconPDF (39 KB)  
    Freely Available from IEEE
  • Table of contents

    Page(s): 733 - 734
    Save to Project icon | Request Permissions | PDF file iconPDF (172 KB)  
    Freely Available from IEEE
  • Foreword to the Special Issue on Ground Penetrating Radar: Modeling Tools, Imaging Methods and Systems Concepts

    Page(s): 735 - 738
    Save to Project icon | Request Permissions | PDF file iconPDF (830 KB)  
    Freely Available from IEEE
  • Clutter Modeling for Ground-Penetrating Radar Measurements in Heterogeneous Soils

    Page(s): 739 - 747
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1615 KB) |  | HTML iconHTML  

    Ground-penetrating radar (GPR) measurement and its interpretation/analysis are challenging when soil is heterogeneous. Soil heterogeneity causes unwanted reflections (i.e., clutter) that disturb reflections from objects of interest. Thorough investigations on soil heterogeneity and clutter are important in order to understand the influence on GPR and assess the performance. In order to observe the influence of heterogeneous soil, an irrigation test was carried out and GPR data were collected after the irrigation and while the distribution of soil water content varied. The correlation length and variability of the dielectric constant of soil were determined by geostatistical analyses of the GPR data. These two parameters were built into a simple model and the Mie solution was theoretically calculated. From this, the power of the backscattered field due to soil heterogeneity was modeled. The results were in agreement with the power of the clutter extracted from the GPR data. Therefore, clutter can be predicted from soil heterogeneity with a simple model using the Mie solution. Furthermore, the result exhibits that scattering by heterogeneous soil is dominated by Mie scattering, rather than Rayleigh scattering, in the studied frequency range. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ground Penetrating Radar: Water Table Detection Sensitivity to Soil Water Retention Properties

    Page(s): 748 - 753
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (625 KB) |  | HTML iconHTML  

    We are interested in Ground Penetrating Radar (GPR) as a geophysical tool useful for determining the depth of the ground water table (GWT) and for monitoring shallow water infiltration in sandy soils. At hydrostatic equilibrium, the water content distribution in a homogeneous unsaturated soil down to the water saturated zone depends on the soil water retention function. A classical way to fit retention curve data is to use the van Genuchten continuous model. Using Finite Difference Time Domain simulations, we study the sensitivity of the GPR signal reflected by a van Genuchten type transition to the hydraulic parameters. We show a power type relationship between the reflected signal amplitude and the slope of the soil retention curve. Furthermore, for simulating GPR reflection data acquired above a transition from unsaturated to saturated soil, geophysicists often approximate the soil water retention curve by a piecewise linear model. We test the validity of such an approximation depending on the frequency of the radar signal and the abruptness of the retention curve. We illustrate our results with high resolution GPR data (1600 MHz) acquired above a fluctuating water table in a sand column at the laboratory scale. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Assessment of an Inverse Algorithm for Cylinders Localization

    Page(s): 754 - 762
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1766 KB) |  | HTML iconHTML  

    We examine how an algorithm for localizing cylinders of arbitrary known radius is affected by errors in the radius knowledge. Reflection mode multi-frequency multi-bistatic configuration is considered. The problem is first examined in far zone, where analytical results can be found. Then, numerical results for the near zone case are provided and a procedure to estimate the cylinder's radius, if it is not known, is introduced. The expected behavior is tested against simulated and experimental data for both perfectly electrical conducting and dielectric cylinders embedded into a lossless homogeneous background. Numerical results of localization of objects embedded into a lossy half space are also shown. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Holographic Subsurface Radar of RASCAN Type: Development and Applications

    Page(s): 763 - 778
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (11994 KB) |  | HTML iconHTML  

    Holographic subsurface radars (HSR) are not in common usage now; possibly because of the historical view amongst radar practitioners that high attenuation of electromagnetic waves in most media of interest will not allow sufficient depth of penetration. It is true that the fundamental physics of HSR prevent the possibility to change receiver amplification with time (i.e., depth) to adapt to lossy media (as is possible with impulse subsurface radar or ISR). However, use of HSR for surveying of shallow subsurface objects, defects, or inhomogeneities is an increasingly proven area of application. In this case, HSR can record images with higher resolution than is possible for ISR images. The RASCAN family of holographic radars is presented along with technical specifications and typical case histories. Among the applications considered are civil and historic building surveys, nondestructive testing of dielectric materials, security applications, and humanitarian demining. Each application area is illustrated by relevant data acquired in laboratory experiments or field tests. This paper presents experiments with RASCAN imaging in media with different degrees of attenuation, and illustrates the principle of HSR through an optical analogy. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Taper-Walled Linearly Tapered Slot Antenna

    Page(s): 779 - 784
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1551 KB) |  | HTML iconHTML  

    Direct coupling among antenna elements is one of the critical problems of array antennas in near-field imaging systems. To mitigate the coupling, we propose taper-walled linearly tapered slot antenna (taper-walled LTSA) to be used in our adaptive ground penetrating radar (GPR) system for visualization of plastic landmines. It is based on the conventional walled LTSA, but the sidewall edges are curved at the aperture and connected to side slits. We analyze the characteristics of the proposed antenna in simulation, and demonstrate in experiment the reduction of the direct coupling in a wideband from 7.2 to 12 GHz which covers the observation frequency of our stepped-frequency adaptive landmine visualization system. The idea is directly usable also in other frequency bands. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Checking the Signal Stability in GPR Systems and Antennas

    Page(s): 785 - 790
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1297 KB) |  | HTML iconHTML  

    The different components of GPR equipment have particular characteristics that, when taken together as a whole, give the system the stability required for correct usage. Besides the information provided by manufacturers about parameters affecting the stability of GPR equipments, their evolution with use and ageing suggest that each GPR system employed in detailed qualitative studies should be subject to routine analysis. This type of analysis is especially important in novel systems and antennas to understand their real capabilities and limitations. In this work, several tests are carried out in order to evaluate the stability of a GPR system working with three different antennas with nominal frequencies of 500, 800, and 1000 MHz. Some tests published by other authors, together with other tests proposed here, are adapted to be the starting point to develop a methodology for calibrating GPR devices and to verify proper operation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Through-Wall Bio-Radiolocation With UWB Impulse Radar: Observation, Simulation and Signal Extraction

    Page(s): 791 - 798
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1417 KB) |  | HTML iconHTML  

    In this paper the cardio-respiratory signatures of human beings were studied using both an ultra-wide band (UWB) impulse radar system in a laboratory through-wall experiment and a numerical simulation using the finite difference time domain (FDTD) method. Signals from both the physical experiment and numerical simulation are processed with the Hilbert-Huang Transform (HHT), a novel signal processing approach for nonlinear and non-stationary data analysis. The results show that by using the HHT, human respiration characteristics can be successfully identified and differentiated for different subjects and a variety of respiratory statuses. However, reliable detection of cardiologic signatures requires a radar system with higher central frequency. Our results demonstrate that this combination of UWB impulse radar and HHT data processing has potential for through-wall life detection and possibly other applications. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Hand-Held GPR Imaging Using Migration for Irregular Data

    Page(s): 799 - 803
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1260 KB) |  | HTML iconHTML  

    Handheld ground-penetrating radar (GPR) system is one of a number of technologies that has been researched as a means of improving landmine detection efficiency. But it is difficult to display landmine imaging in horizontal slices, because human being operator cannot collect regular GPR data along the survey line and the measurement positions are random. Also detection of buried landmines by GPR normally suffers from very strong clutter that will decrease the image quality. So we proposed two processing procedures to achieve hand-held GPR subsurface imaging. One processing procedure is composed of interpolation and migration algorithm. The interpolation is chosen to produce the regular grid data set. The migration is used to improve signal-clutter ratio and reconstruct subsurface imaging. In the other processing procedure we developed a simply modified migration algorithm that can directly processes irregular GPR data. Two processing procedures, migration with interpolation and modified migration without interpolation, were applied to a field experiment data respectively. Both of processing procedures can efficiently process irregular GPR data and achieve subsurface imaging of high quality. The imaging processed by migration with interpolation is used in the dual sensor, advanced landmine imaging system (ALIS), and two sets of ALIS have detected more than 80 AP-mines since 2009. Also the modified migration algorithm can save the processing time, which is important for field real-time signal processing. We concluded that to achieve clear hand-held GPR imaging, the interpolation is not necessary algorithm and the migration is the key algorithm. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On Mapping Surface Moisture Content of Japanese Andisol Using GPR

    Page(s): 804 - 808
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1065 KB) |  | HTML iconHTML  

    Ground penetrating radar (GPR) ground wave was used to monitor the surface soil-moisture content distributions at a natural Japanese Andiol (i.e., Kanto loam) site. The study site was maintained as bare during three month monitoring period. The results obtained from ground wave analysis showed non-uniformity in moisture content distribution. However the zones of higher moisture content were found at similar locations among different times, with or without precipitation events between observation times. This indicates that surface soil moisture dynamics are more-or-less location (i.e., topography, soil physical properties) dependent. Our study highlighted the use of GPR ground wave as a skillful way to execute noninvasive moisture content mapping of Japanese Andisol. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Automatic Segmentation of Multi-Beam Data for Predictive Mapping of Benthic Habitats on the Chella Seamount (North-Eastern Alboran Sea, Western Mediterranean)

    Page(s): 809 - 813
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (999 KB) |  | HTML iconHTML  

    A reliable and objective classification method has been produced for the differentiation of benthic habitats in the seamount regions of the North-Eastern Alboran Sea. Acoustic backscatter and depth measurements from multi-beam data are automatically fused and then classified using video transects of known cold-water coral ecosystems as ground-truth. Results of the classification reveal the locations of potentially similar habitats in the region, and could be used as a base map for the planning of future scientific campaigns in the area. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Deriving Water Fraction and Flood Maps From MODIS Images Using a Decision Tree Approach

    Page(s): 814 - 825
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2498 KB) |  | HTML iconHTML  

    This study investigates how to derive water fraction and flood mapping from the Moderate-Resolution Imaging Spectroradiometer (MODIS) onboard the Earth Observing System (EOS) satellites using the linear mixture model and decision-tree approach. The recent floods in the Midwestern United States in June 2008 and in the New Orleans area in August 2005 were selected for this study. MODIS surface reflectance with the matched land cover data in the Midwest prior to the flooding events were used for the training dataset, with the split test mode of 50% for training and the remaining 50% for testing. The precision, or accuracy rate, of the water classification reaches over 90% from the test. Our results demonstrate that the reflectance difference (CH2-CH1) between the MODIS channel 2 (CH2) and channel 1 (CH1) is the most useful parameter to derive water fraction from the linear mixture model. Rules and threshold values from the decision tree training were applied to real applications on different dates (June 1, 17, and 19, 2008 for the Midwestern region of the U.S.) and at different locations (New Orleans in 2005) to identify standing water and to calculate water fraction. The derived water fraction maps were evaluated using higher resolution Thematic Mapper (TM) data from Landsat observations. It shows that the correlation between water fractions derived from the MODIS and TM data is 0.97, with difference or “bias” of 4.47%, standard deviation of 4.40%, and root mean square error (rmse) of 6.28%. Flood distributions in both space and time domains were generated using the differences in water fraction values before and after the flooding. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Study of Decadal Coastal Changes on Western Taiwan Using a Time Series of ERS Satellite SAR Images

    Page(s): 826 - 835
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4592 KB) |  | HTML iconHTML  

    In this paper, coastal line changes were monitored and analyzed from a sequence of ERS-1/2 SAR images covering the years 1996 to 2005, totaling 44 images for each year. Waterlines were extracted using a multi-scale edge detection algorithm, and further refined by means of morphology. Substantial analysis was carried out in conjunction with ground survey and sonar bathymetric mapping. In addition, tidal records were used to ensure all the shore lines been calibrated to the same tidal level. Results showed that Waisanting Sandbar, a north-southward sandbar, experienced significant accretion and erosion, moving southward about 700 meters during a 10-year period, and shrinking to just one third of its 1996 size. The surrounding coastal waters and the estuary of the Peikang River receded substantially, moving inward toward the coastal flat. The water channel became even more heavily deposited as a result. Finally, Haifengdao Sandbar, another sandbar, moved southward about 1.5 km, although its size remained the same from 1996 to 2005. It also showed a clear tendency to receding inward. We conclude that satellite remote sensing by SAR, aided by ground tidal data, bathymetric maps, and optical images, provides an effective and efficient tool for understanding coastal processes over large areas of coverage and long time spans. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Novel Filtering Algorithm for Bare-Earth Extraction From Airborne Laser Scanning Data Using an Artificial Neural Network

    Page(s): 836 - 843
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1266 KB) |  | HTML iconHTML  

    The extraction of bare-earth points from airborne laser scanning (ALS) data and the generation of high-quality digital terrain models (DTMs) are important research challenges. In this study, a novel filtering algorithm based on artificial neural networks (ANNs) is proposed to extract bare-earth points from ALS data efficiently. An efficient set of conditions were defined to choose the training data semi-automatically when an expert user is not available. Four standard study sites were used to evaluate the performance of the method. The obtained results were compared with four popular filtering algorithms based on type I error, type II error, the kappa coefficient and the total error. First echoes were used in the proposed method to increase the reliable detection of vegetated areas. The proposed algorithm has an easy implementation procedure and low computational costs. The results obtained for both semiautomatic and supervised training data selection reveal acceptable accuracies, especially for type II errors. Use of this algorithm would lead to high-quality DTM generation using accurately identified bare-earth points in urban areas. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Understanding the Dynamics of Transfer of Satellite Rainfall Error Metrics From Gauged to Ungauged Satellite Gridboxes Using Interpolation Methods

    Page(s): 844 - 856
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2138 KB) |  | HTML iconHTML  

    Knowledge of error characteristics of high resolution satellite rainfall data at different spatial/temporal scales is useful, especially when the scheduled Global Precipitation Mission (GPM) plans to provide High Resolution Precipitation Products (HRPPs) at global scales. Satellite rainfall data contain errors which need ground validation (GV) data for characterization, while satellite rainfall data will be most useful in the regions that are lacking in GV data. Therefore, a critical step to bridge this gap is to assess spatial interpolation schemes for transfer of the error characteristics from GV regions to non-GV regions. In this study, a comprehensive assessment of kriging methods for spatial transfer (interpolation) of error metrics is performed. Three kriging methods for spatial interpolation are compared, which are: ordinary kriging (OK), indicator kriging (IK) and disjunctive kriging (DK). Additional comparison with the simple inverse distance weighting (IDW) method is also performed to quantify the added benefit (if any) of using geostatistical methods. Four commonly used satellite rainfall error metrics are assessed for transfer to non-GV satellite gridboxes: Probability of Detection (POD) for rain, False Alarm Ratio (FAR), bias (BIAS), and Root Mean Squared Error (RMSE). Results show that performance of a kriging scheme is strongly sensitive to the timescale for which the errors are interpolated (monthly and weekly) wherein the extent of coverage by GV data plays an equally sensitive role. While most kriging techniques perform well according to correlation measure at climatologic timescales for a range of GV data coverage, only DK and OK appear to retain accuracy at the shorter timescales (monthly and weekly). However, scalar assessment metrics such as mean and standard deviation of error (i.e., difference between true and interpolated errors) reveal a completely different picture of accuracy of each interpolation method. In terms of such assessment measu- - res, the overall performance ranking of the kriging methods is as follows: OK=DK >; IDW >; IK. Assessment of kriging methods also revealed that the transfer accuracy is sensitive to error metric type. The ranking of error metrics with highest accuracy in transfer is: POD >; FAR >; RMSE >; BIAS. Overall, the assessment of kriging methods revealed that these best linear unbiased spatial estimators may not be appropriate transfer methods for transfer of satellite rainfall error metrics at time scales shorter than a week. It is worthwhile now to pursue more non-linear transfer methods (such as neural networks) and other kriging methods that use additional spatial information on the rainfall process (such as co-kriging) to further constrain the interpolation uncertainty. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Determining Selected Tropical Cyclone Characteristics Using QuikSCAT's Ultra-High Resolution Images

    Page(s): 857 - 869
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2734 KB) |  | HTML iconHTML  

    Operational SeaWinds on QuikSCAT data can be enhanced to yield a 2.5 km ultra-high resolution (UHR) wind product, which can be used to help estimate tropical cyclone (TC) characteristics such as TC center and wind radii. This paper provides the results of two studies in which the QuikSCAT UHR wind product's effectiveness in estimating these TC characteristics is evaluated. First, a comparison is made between an analyst's choice of center location based on UHR images and interpolated best track position. In this analysis, the UHR images are divided into two categories based on the analyst's confidence level of finding the center location. In each category, statistical error quantities between the analyst's choice of center location and interpolated best track location are computed. UHR images within the high-confidence category can provide, for a given year and basin, mean error distance as small as 19 km with a 10 km standard deviation. Second, a comparison of QuikSCAT's performance in estimating wind radii is made. QuikSCAT's performance is gauged against the H*wind dataset and the extended best track (EBT) dataset. Results show that QuikSCAT UHR data yields the correct 34 kt wind radius most of the time regardless of the TC category when compared to both H*wind and EBT, whereas the 50 kt and 64 kt wind radii estimates do not always agree with H*wind and EBT. A more sophisticated method is implemented to automatically estimate wind radii based on a model fit to QuikSCAT data. Results from this method are compared with EBT wind radii. The 50 kt and 64 kt wind radii obtained from QuikSCAT model fit are generally highly correlated with EBT estimated wind radii. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Combining GeoEye-1 Satellite Remote Sensing, UAV Aerial Imaging, and Geophysical Surveys in Anomaly Detection Applied to Archaeology

    Page(s): 870 - 876
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1384 KB) |  | HTML iconHTML  

    This paper describes a method of combined ultra-high resolution satellite imaging, unmanned aerial vehicle (UAV) photography, and sub-surface geophysical investigation for anomaly detection, which was employed in a non-invasive survey of three archaeological sites in Northern Mongolia. The surveyed sites were a Bronze Age burial mound, a Turkish period tomb, and a steppe city fortification of unknown origin. For the satellite survey, 50 cm resolution pan-sharpened imagery was generated through a combination of multispectral and panchromatic data, collected from the GeoEye-1 earth-sensing satellite. The imagery was then used to identify the location of the aforementioned sites in an approximate area of 3000 km2 . Aerial photographs of the sites were obtained with two customized electric-powered UAVs: a fixed flying wing rear-propulsion plane and a multi-propeller “oktokopter” helicopter system. Finally, geophysical investigation was conducted with a GSM-19 Overhouser gradiometer, an EM38 electromagnetometer, and an IDS Detector Duo ground penetrating radar. The satellite imagery and aerial photographs were combined with the geophysical survey results and on-site surface observations to provide insight and contextual information about anomalies in multiple layers of data. The results highlight the effectiveness and robustness of the employed method for archaeological investigation in large, rugged and scarcely populated areas. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Theoretical Model for Estimating the Scaling Error of the Two-Band Ratio of Red to Near-Infrared in Inhomogeneous Pixels: Simulation Using a Moving Window

    Page(s): 877 - 881
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (955 KB) |  | HTML iconHTML  

    This study develops a theoretical model to estimate the scaling error of the two-band ratio of red to near-infrared (TBRRN) in an inhomogeneous pixel. Three different imageries and a 3 × 3 moving window are used to verify and approximately estimate the scaling error of the TBRRN for remote-sensing imageries. The datasets are Landsat Thematic Mapper (Landsat/TM) imagery taken on 15 October 2005, satellite probatoire d'Observation de la terre (SPOT) imagery taken on 7 September 2005, and moderate-resolution imaging spectroradiometer (MODIS) imagery taken on 5 October 2005 of the Yellow River Estuary. It is found that 1) about 15.70%, 17.24% and 26.52% of SPOT, Landsat/TM and MODIS pixels have relative scaling error higher than 2% respectively, 2) the average relative scaling error increases with increasing scale of the image pixel, and 3) it is difficult to achieve the goal of the National Aeronautics and Space Administration of obtaining valid ocean-color data of the world's oceans for estimating the chlorophyll-a concentration with uncertainty of less than 35% if the scaling error cannot be effectively reduced. Our results suggest the need for an in-depth study of scaling errors in water-color remote sensing. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Atmospheric Correction Algorithm for Landsat/TM Imagery Basing on Inverse Distance Spatial Interpolation Algorithm: A Case Study in Taihu Lake

    Page(s): 882 - 889
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1138 KB) |  | HTML iconHTML  

    In this study, an atmospheric correction algorithm is designed for Landsat/TM imagery. The lookup tables with multiple scattering and polarization correction are used to remove the reflectance resulting from Rayleigh scattering. The Landsat/TM imageries collected on October 28, 2003, in Taihu Lake, water-leaving reflectance measured by synchronized experiments and the aerosol lookup table are used to estimate the aerosol optical thickness (AOT) and atmospheric diffuse transmittance from Landsat/TM imagery at 15 experimental stations. The inverse distance spatial interpolation algorithm (IDSIA) is used to improve the uncertainty produced by the non-homogeneous distribution of AOT. According to the study results carried out by this paper, it is found that using IDSIA to improve the spatial changes of AOT at least decreases 4.5% uncertainty at TM3 and 16.4% uncertainty at TM4 from non-homogeneous distribution of AOT. The improved performance of IDSIA is fairly obviously. Additionally, water-leaving reflectance of Landsat imageries is estimated by this atmospheric correction algorithm. The stability and accuracy validation results show that the estimation accuracy of water-leaving reflectance is 8.31% at TM1 and 9.56% at TM2, respectively. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Detecting an Optimal Scale Parameter in Object-Oriented Classification

    Page(s): 890 - 895
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2116 KB) |  | HTML iconHTML  

    Avoiding spatial autocorrelation is the key to many research questions especially for field design, remote sensing data selection, and maximum spatial variation caption. Spatial variation across land cover types as well as the gradients inherent in ecotones can be captured in reflectance which is a spatially continuous variable. The spatial variation between reflectance values of any two pixels will depend on the lag distance beyond which pixels are no longer spatially autocorrelated. This paper demonstrates the utility of semivariogram for determining the lag distance in which pixels will be spatially autocorrelated. According to sampling theorem, objects should be sampled at half their width such that spatial resolution should be half of the semivariogram lag distance. As object-oriented classification is now the most broadly accepted classification method, scale parameter determination is the foremost important decision for determining the size of image objects. The scale parameter was adjusted during image segmentation to test how the size of image objects changed. The optimal scale parameter was chosen when the average distance between neighbouring image object centroids was near to the lag distance of the semivariogram. Results showed that the size of image objects reached a scaling threshold as the scale parameter was increased. When the scale parameter was adjusted to create image objects that exceeded this threshold, the segmentation was not able to accurately represent the spatial variation observed on the ground. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Wind Speed Estimation Using Polarimetric RADARSAT-2 Images: Finding the Best Polarization and Polarization Ratio

    Page(s): 896 - 904
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1589 KB) |  | HTML iconHTML  

    As the number of operational wind scatterometers is getting smaller, other sources of spaceborne sensors are now included in global wind mapping. One of the prominent sensors is the Synthetic Aperture Radar (SAR). Besides serving as a generic scatterometer, SAR systems are the only type of radar systems that can provide sub-km resolution sea surface wind data and offers near shore mapping capability. This unique feature is important for assessing the offshore wind resources. As an important source of renewable energy, offshore wind farms are growing rapidly. Furthermore, recent research shows that the cross-polarization radar backscatter does not seem to saturate in high winds, and provides an excellent supplement for scatterometer wind sensing in storm conditions. The saturation issues of co-polarization radar returns have so far made it difficult to resolve wind speeds beyond roughly 20 m/s, or even less for lower incidence angles. The scope of this paper is to show the potential of RADARSAT-2's polarimetric modes for wind speed retrieval. RADARSAT-2 is the first operational fully polarimetric (HH VV HV VH) C-band satellite. Standard Quad-pol images have been collected in the St. Lawrence Gulf and compared against the Mont-Louis buoy and QuikSCAT scatterometer data. Co-polarization wind speeds were computed with CMOD-5 algorithms. A few polarization ratios were tested to determine the most suitable one for RADARSAT-2's HH polarization mode. For Cross-polarization, two different models were compared. Cross-polarization gives excellent results when wind exceeds 5 m/s. In general, SAR wind retrieval is suitable for resolution of 400 m. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Delineating the Natural Features of a Cadastral Shoreline in South Korea Using Airborne Laser Scanning

    Page(s): 905 - 910
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4052 KB) |  | HTML iconHTML  

    This study presents the possible application of the airborne Light Detection And Ranging (LiDAR) survey technique to extract a cadastral shoreline in South Korea for the first time. This paper summarizes the results of two case studies to compare the airborne LiDAR-derived shoreline with other data sources, such as the digital topographic map, the seamless cadastral map, and the cadastral surveying. In this current study, the well-known contouring method is used to extract shorelines in combination with LiDAR-derived Digital Elevation Models (DEMs) and digital aerial images. Approximate Highest High Water Level (AHHWL) published by the Korea Hydrographic and Oceanographic Administration (KHOA) is introduced as the tidal reference elevation. This is close to a legally defined shoreline for the cadastral shoreline mapping in South Korea. The comparison results show that some discrepancies are found between the applied methods mentioned due to the inconsistent tidal data references and the heterogeneous data sources. However, it is verified that the airborne LiDAR surveying can lead to this method's increasing applications in the cadastral shoreline mapping. This is only possible under conditions of a new guideline for LiDAR surveying and re-establishment of the tidal reference. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing (J-STARS) addresses current issues and techniques in applied remote and in situ sensing, their integration, and applied modeling and information creation for understanding the Earth.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Dr. Jocelyn Chanussot
Grenoble Institute of Technology