Comparison of Aster and SRTM Digital Elevation Models at One-Arc-Second Resolution Over Turkey (original) (raw)
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Accuracy Assessment of Aster Global Dem Over Turkey
2010
The aim of this study is to analyze the accuracy of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) over Istanbul metropolitan city. Accuracy assessment was conducted by comparing ASTER GDEM with a reference DEM derived from 1/5.000-scaled topographic maps. The selected area has wide range of elevations since it covers coastal and mountainous areas. Different land cover types like urban, sea, lakes, agricultural land, forest, grasslands, bare lands are available within the study area. The accuracy assessment of GDEM was performed by visual interpretation and statistical analysis. Throughout the statistical analysis, several transects representing different types of land cover and topography were selected and minimum, maximum and mean errors and Root Mean Square Error values of each transect were calculated, respectively. The quality of ASTER GDEM was analyzed for Istanbul region and it was found that ASTER GDEM could repre...
Comparison of new and existing global digital elevation models: ASTER G-DEM and SRTM3
Geophysical Research Letters, 2008
1] A new global elevation dataset known as G-DEM, based on the ASTER satellite imagery, will be released in late 2008. G-DEM will be the best freely available global digital elevation model (DEM) at a horizontal resolution of 1 arc second. We assess the quality of G-DEM in comparison with 3-arc-second SRTM DEM, the best current global elevation dataset. Basic geomorphometric parameters (elevation, slope and curvature) were examined for a prerelease version of G-DEM and SRTM DEM for western Japan. G-DEM has fewer missing cells than SRTM DEM, particularly in steep terrain. Also, G-DEM gives smoother and more realistic representations of lowlands, valleys, steep slopes, and mountain ridges, whereas, SRTM DEM includes many local spikes and holes, and tends to overestimate valley-floor elevation and underestimate ridge elevation. G-DEM will be commonly used in geoscientific studies, because of its higher resolution, fewer missing data, and better topographic representation than SRTM DEM.
Comparison of SRTM DEM and ASTER GDEM over the Lebanese territory
Digital elevation models derived from satellite sensors, as SRTM(Space Shuttle Radar Topography Mission) and ASTER (Advance Space borne Thermal Emission and Reflection Radiometer) are freely available on the internet and over the last few years have been used by several researchers. The main scope of the work is to assess the accuracy of the tested ASTER and SRTM products over the Lebanese territory by a comparison with 50 ground elevation points taken from topographic maps, in order to understand potentials of such DEMs and have the ability to select the appropriate one for different geographical applications. Until now, DEM users especially students would often apply the DEM as a truth surface rather than as a model without studying it characteristics and taking a primary idea about its vertical accuracy, this comparison is one among a wide research results which can be an answer for which DEM is more suitable for geographic researches.
Accuracy Assessment of Digital Elevation Model (DEM) Data Obtained from ASTER Satellite in Flat Land
IOP Conference Series: Materials Science and Engineering
It is important to investigate the accuracy of Digital Elevation Models (DEMs) because of their crucial impact on all engineering and scientific disciplines. Photogrammetry, traditional surveying, remote sensing systems and satellite whole DEMs output methods. In this paper include the DEM data produced by the ASTER satellite (Band near-infrared wavelength region from 0.78 to 0.86 μm), where tested and evaluation DEM data for an area of 100 square kilometers in Al-Shtra city. The technique used to evaluate was twofold: first method was to use statistical methods; second method is to take advantage of applied linear transformation equation to detect the gap between Z-DEM and Z-Global Navigation Satellite System (GNSS) (which represents reality (. The result of a root means square error (RMSE) is 5.087m, where it was calculated based on the observed data in the field using GNSS. And standard deviation error (SDT err) was 5.088 m, while after applied linear transformation equation the RMSE reduction to about 80%, which indicates a large bias between the Z-DEM and Z-GPS.
SRTM vs ASTER elevation products. Comparison for two regions in Crete, Greece
The Shuttle Radar Topography Mission (SRTM) collected elevation data over 80% of earth's land area during an 11-day Space Shuttle mission. With a horizontal resolution of 3 arc sec, SRTM represents the best quality, freely available digital elevation models (DEMs) worldwide. Since the SRTM elevation data are unedited, they contain occasional voids, or gaps, where the terrain lay in the radar beam's shadow or in areas of extremely low radar backscatter, such as sea, dams, lakes and virtually any water-covered surface. In contrast to the short duration of the SRTM mission, the ongoing Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is continuously collecting elevation information with a horizontal resolution of 15 m. In this paper we compared DEM products created from SRTM data with respective products created from ASTER stereo-pairs. The study areas were located in Crete, Greece. Absolute DEMs produced photogrammetricaly from ASTER using differentially corrected GPS measurements provided the benchmark to infer vertical and planimetric accuracy of the 3 arc sec finished SRTM product. Spatial filters were used to detect and remove the voids, as well as to interpolate the missing values in DEMs. Comparison between SRTM-and ASTER-derived DEMs allowed a qualitative assessment of the horizontal and vertical component of the error, while statistical measures were used to estimate their vertical accuracy. Elevation difference between SRTM and ASTER products was evaluated using the root mean square error (RMSE), which was found to be less than 50 m.
Assessment of the global digital elevation models ASTER and SRTM in Greece
Survey Review, 2014
This study evaluates the height accuracy of the free to download global digital elevation models (DEMs): advanced spaceborne thermal emission and reflection radiometer (ASTER) global digital elevation model (GDEM) and shuttle radar topography mission (SRTM) for the area of Greece. The analysis is done in two ways; using control points with known elevation and accurate DEMs. Quantitative and qualitative assessments are made both for the whole country, and for specific regions (test sites). Using the DEMs of SRTM with coverage from 56uS to 60uN and ASTER GDEM with coverage from 83uS to 83uN, the elevation information is available to users free of charge almost worldwide. In the regions where both data sets exist, the question arises which one is best to use; the decision is based on a series of parameters, such as accuracy, homogeneity, reliability, completeness, performance of morphological features, as well as the purpose of the work for which the elevation information will be used. These parameters are reviewed and analysed using data covering Greece. The data come from various providers and varying formats. The evaluation of the results highlights the need for a 'fit for purpose' use of each of these DEMs, taking into consideration the implementation constraints (technical and qualitative specifications of each project), along with the usefulness of these DEMs for a wide range of applications.
Google Earth’s derived digital elevation model: A comparative assessment with Aster and SRTM data
This paper presents a statistical analysis showing additional evidence that Digital Elevation Model (DEM) derived from Google Earth is commendable and has a good correlation with ASTER (Advanced Space-borne Thermal Emission and Reflection Radiometer) and SRTM (Shuttle Radar Topography Mission) elevation data. The accuracy of DEM elevation points from Google Earth was compared against that of DEMs from ASTER and SRTM for flat, hilly and mountainous sections of a pre-selected rural watershed. For each section, a total of 5,000 DEM elevation points were extracted as samples from each type of DEM data. The DEM data from Google Earth and SRTM for flat and hilly sections are strongly correlated with the R 2 of 0.791 and 0.891 respectively. Even stronger correlation is shown for the mountainous section where the R 2 values between Google Earth's DEM and ASTER's and between Google Earth's DEM and SRTM's DEMs are respectively 0.917 and 0.865. Further accuracy testing was carried out by utilising the DEM dataset to delineate Muar River's watershed boundary using ArcSWAT2009, a hydrological modelling software. The result shows that the percentage differences of the watershed size delineated from Google Earth's DEM compared to those derived from Department of Irrigation and Drainage's data (using 20m-contour topographic map), ASTER and SRTM data are 9.6%, 10.6%, and 7.6% respectively. It is therefore justified to conclude that the DEM derived from Google Earth is relatively as acceptable as DEMs from other sources.
Journal of Geographic Information System, 2015
Digital Elevation Models (DEMs) provide one of the most useful digital datasets for a wide range of users. Both the Shuttle Radar Topographic Mission (STRM V.4.1) topography and the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER-GDEM V.2) have been widely used in geomorphology, hydrology, tectonic, and others since they were made access to the public. The magnitude of vertical errors of two near-global DEMs-SRTM and ASTER-GDEM is compared and validated against a reference DEM which has a relatively high precision of 1:25,000 scale constructed from topographical map. Moreover, the reference DEM, ASTER-GDEM and SRTM were used as basic topographic data to extract some Morphometric index. The parameters like slope and shaded reflectance maps, were derived from the elevation distribution to provide a more sensitive indication of DEM quality. A square area in the North East of Tunisia was selected as a case study to test and evaluate the elevation accuracy of ASTER-GDEM and SRTM. The relative accuracy approach and absolute accuracy were adopted to evaluate global DEMs. The comparisons show that SRTM overestimates and ASTER-GDEM underestimates elevations, both DEMs can be used to extract the elevations of required geometric data, i.e. sub watershed boundaries, drainage information and cross sections. However, small errors still exist in. The lower root mean square errors values indicate that SRTM is comparatively more accurate than ASTER-GDEM.
Remote Sensing, 2014
Digital Elevation Models (DEMs) including Advanced Spaceborne Thermal Emission and Reflection Radiometer-Global Digital Elevation Model (ASTER GDEM), Shuttle Radar Topography Mission (SRTM), and Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) are freely available for nearly the entire earth's surface. DEMs that are usually subject to errors need to be evaluated using reference elevation data of higher accuracy. This work was performed to assess the vertical accuracy of the ASTER GDEM version 2, (ASTER GDEM2), the Consultative Group on International Agriculture Research-Consortium for Spatial Information (CGIAR-CSI) SRTM version 4.1 (SRTM v4.1) and the systematic subsample GMTED2010, at their original spatial resolution, using Global Navigation Satellite Systems (GNSS) validation points. Two test sites, the Anaguid Saharan platform in southern Tunisia and the Tebessa basin in north eastern Algeria, were chosen for accuracy assessment of the above mentioned DEMs, based on geostatistical and statistical measurements. Within the geostatistical approach, empirical variograms of each DEM were compared with those of the GPS validation points. Statistical measures were computed from the elevation differences between the DEM pixel value and the corresponding GPS point. For each DEM, a Root Mean Square Error (RMSE) was determined for model validation. In addition, statistical tools such as frequency histograms and Q-Q plots were used to OPEN ACCESS Remote Sens. 2014, 6 4601 evaluate error distributions in each DEM. The results indicate that the vertical accuracy of SRTM model is much higher than ASTER GDEM2 and GMTED2010 for both sites. In Anaguid test site, the vertical accuracy of SRTM is estimated 3.6 m (in terms of RMSE) 5.3 m and 4.5 m for the ASTERGDEM2 and GMTED2010 DEMs, respectively. In Tebessa test site, the overall vertical accuracy shows a RMSE of 9.8 m, 8.3 m and 9.6 m for ASTER GDEM 2, SRTM and GMTED2010 DEM, respectively. This work is the first study to report the lower accuracy of ASTER GDEM2 compared to the GMTED2010 data.
Comparison of spot, SRTM and ASTER DEMs
Digital Elevation Models (DEMs) represent the terrain elevation in discrete form in three-dimensional space. This is the simplest form of 3D-terrain representation and the most common. The accuracy and morphologic details of the height models represent the quality. With SPOT-5 and ASTER stereo models DEMs have been generated in the Zonguldak test field, located in Turkey at the Black Sea coast. In addition to these, also the height models of the Shuttle Radar Topography Mission (SRTM) from C-band and also from X-band have been analyzed. The SRTM C-band and X-band data have been obtained with single-pass Interferometric Synthetic Aperture Radar (InSAR) technique. SRTM C-band has 3 arcsec and X-band 1 arcsec point spacing with 1 arcsec corresponding to approximately 30m at the equator. The height models from the optical space sensors have been generated with three times the ground sampling distance (GSD) corresponding to 15m for SPOT-5 and 45m for ASTER. As reference a DEM from large ...