:: Volume 3, Issue 3 (2-2014) ::
JGST 2014, 3(3): 75-86 Back to browse issues page
Comprehensive Assessment of ASTER GDEM Ver2
F. Alidoost *, F. D. Javan
Abstract:   (5214 Views)
Digital elevation models (DEMs) are one of the most important data for various applications such as hydrological studies, topography mapping, image ortho rectification, 3D images generation, extraction terrain parameters, disaster management, and etc. A digital elevation model can be derived from numerous techniques with different elevation accuracies. In photogrammetric techniques, a DEM can be extracted from stereo satellite images through many processing steps. A satellite imagery based digital elevation model is called ASTER GDEM ver2 was released on 2011 at a spatial resolution of 1 arc-second. This model was evaluated by differencing with other reference DEMs in order to investigate the quality and accuracy parameters over different land cover types. In this paper, an accuracy assessment of ASTER GDEM ver2 dataset with SRTM and local elevation model over the bare area of a port in southwest of IRAN is presented. This study investigates DEM’s characteristics such as systematic error (bias), vertical accuracy and outliers for these three datasets. The accuracy measures for the assessment of the height differences between each DEMs can be calculated based on the usual (Mean error, Root Mean Square Error, Standard Deviation) and the robust (Median, Normalized Median Absolute Deviation, Sample Quantiles) descriptor. The results demonstrated that there is a large negative elevation bias of approximately -4.5 m and -2.8 m of ASTER GDEM ver2 against the SRTM and local DEM. The median of the differences between GDEM and local DEM is about -3.7 m which is a robust measure to prove the existence of systematic shift between the two data. The RMSE measured for elevation differences between GDEM and two other DEMs is same, but the standard deviation GDEM and local DEM differences are higher than the value of this parameter between GDEM and SRTM. The accuracy measures NMAD of GDEM against the local DEM and SRTM are 5.5 m and 5.9 m, respectively. On the other hand, about 68% of the GDEM and local DEM elevation differences are in [0, 7.5] m, while this values are in [0, 9] m for GDEM and SRTM elevation differences.
Keywords: ASTER GDEM, Digital Elevation Models, Absolute Errors, NMAD, SRTM
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Type of Study: Research | Subject: Photo&RS

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Volume 3, Issue 3 (2-2014) Back to browse issues page