Slope Values Accuracy vs Resolution of the Digital Elevation Models (Example of the Republic of Macedonia) (original) (raw)
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SLOPE VALUES ACCURACY VS RESOLUTION OF THE DIGITAL ELEVATION MODELS
Proceedings from the ICC&GIS 2014, Varna, Bulgaria, 2014
In this study, analysis of slope angle accuracy measured from the available digital elevation models (DEM) covering the area of the Republic of Macedonia is made. Aside of global coarse to fine scale DEM’s (30"SRTM, 3"SRTM, 1"ASTER GDEM), two of the national 20 m and 5 m DEM’s are processed. Several test areas with different topography (plains, hilly-mountains and mountains) are selected for detailed analysis. Final data are compared with 5 m DEM which is used as a referent and most accurate model previously validated with traditional cartographic measurements from 25K topographic maps. Results show significant differences and degree of inaccuracy which grown from fine-scale to coarse scale DEM’s, and from flat areas to areas with high vertical relief. For minimize of these DEM’s-resolution related errors, several simple equations are realized.
Improvement of Slope Angle Models Derived from Medium to Fine-Scale DEMs
Geomorphometry 2015, 2015
Apart from freely available global to near-global medium-resolution DEMs (1-3"SRTM, 1"ASTER), for the territory of the Republic of Macedonia, three additional high quality DEMs are available. They are as follows: 20m and 5m DEM of the Agency of Real Estate and Cadastre (AREC) and 15m DEM filtered from original 5m DEM. For general purposes, horizontal and vertical accuracy of all of those models (even the freely available ones) is acceptable. But in fine-scale terrain applications and modellings, slope accuracy is much more sensitive and uncer¬ta¬in. Instead of assessment only, some kind of DEM-related slope accuracy correction and improvement is very useful. An example of such a procedure is presented in the current paper.
Generation and Accuracy Assessment of Digital Elevation Models in Mountain Area
2015
Nowadays DEMs are indispensable tools in studies and analysis regarding Earth’s surface. Generating DEMs closely to the true surfaces and with high accuracy represent a main issue. The aim of the study is to improve the geomorphometric analysis based on DEMs. In this study a statistical approach was used to assess various DEMs generated with different methods to compare their accuracy. DEMs were created on the base of a topographic map using classical interpolation methods (Spline, IDW, Kriging, Simple linear interpolation) and simulated surfaces. The results suggest that data source is more important in error propagation, followed by interpolation methods.
Journal of Earth Science and Engineering, 2017
SRTM DEM (shuttle radar topographic mission digital elevation model) and ASTEMR DEM (advanced space-borne thermal emission and reflection radiometer digital elevation model) are now freely available in two resolutions: 90 m and 30 m. DEM is a computerized representation of the Earth's relief, and is used in many applications such as hydrology, climatology, geomorphology and ecology. There are some important differences in assessing the accuracy of digital elevation models for specific applications. The purpose of this study is to investigate the errors in digital elevation models obtained globally from DEMs 90 m, 30 m ground resolution, and the extracted DEM from a topographic map by digitized contour lines of 1:50,000 scale in a rugged mountainous region and a heterogeneous landscape, using KS (kernel smoothing) interpolation method. For validation purposes, datasets of 250-GCPs (ground control points) distributed over the study area were used to evaluate and compare the accuracy of the two global Dems and the DEM extracted from TM. The main results showed that the 30 m resolution global (DEM) is the most accurate one among the three. According to the validation results, SRTM with maximum (+) and minimum (-) error elevation is-10_9. M, with mean deviation of KS is-0.00238667, and RMS (root-mean-square) error of 0.98, and currently the most accurate model is 30 m DEM of the study area with no significant differences compared with DEM 90 m.
Evaluation of vertical accuracy of open source Digital Elevation Model (DEM)
International Journal of …
Digital Elevation Model (DEM) is a quantitative representation of terrain and is important for Earth science and hydrological applications. DEM can be generated using photogrammetry, interferometry, ground and laser surveying and other techniques. Some of the DEMs such as ASTER, SRTM, and GTOPO 30 are freely available open source products. Each DEM contains intrinsic errors due to primary data acquisition technology and processing methodology in relation with a particular terrain and land cover type. The accuracy of these datasets is often unknown and is non-uniform within each dataset. In this study we evaluate open source DEMs (ASTER and SRTM) and their derived attributes using high postings Cartosat DEM and Survey of India (SOI) height information. It was found that representation of terrain characteristics is affected in the coarse postings DEM. The overall vertical accuracy shows RMS error of 12.62 m and 17.76 m for ASTER and SRTM DEM respectively, when compared with Cartosat DEM. The slope and drainage network delineation are also violated. The terrain morphology strongly influences the DEM accuracy. These results can be highly useful for researchers using such products in various modeling exercises.
Users of digital elevation models must be aware of their main characteristics in order to judge better their suitability for a specific application. In this study, a comparison and evaluation of the characteristics of seven publicly available global digital elevation models were made for territory of the Republic of Croatia. The models chosen were: ASTER, SRTM, SRTM30+, ACE2, GMTED2010, GTOPO30 and ETOPO1. For each digital elevation model, the most important characteristics are given: construction methods, resolution, horizontal and vertical datum, and estimated accuracy. In addition, in relation to Croatia as a whole, differences between digital elevation models at identical points were determined and analysed, after the models had been adjusted to the same resolution. The model differences yielded information on the mutual correspondence between the models and areas of disagreement, and allowed an evaluation of the presence of major, systematic errors indicating the existence of s...
Method for vertical accuracy assessment of digital elevation models derived from remote sensing data
Revista Geográfica venezolana, 2020
The objective of the present study was to propose a method for evaluating the vertical accuracy of digital elevation models (DEMs), which is applicable to the quality control process in the production line of the Sub-Directorate of Geography and Cartography of the Agustín Codazi Geographic Institute (Subdirección de Geografía y Cartografía del Instituto Geográfico Agustín Codazzi [IGAC]), which also fulfills the institutional quality objectives. The proposed method outlines the steps for the following: 1) the definition of acceptance levels based on an uncertainty analysis of the sources of error inherent to DEMs; 2) the determination of the sampling design (method and size) as a function of the terrain characteristics (slope and cover); and 3) the assessment of the vertical accuracy based on different statistical measures for quantifying the error. The effectiveness of the method was tested through its application to a DEM data set generated by the Sub- Directorate of Geography and Cartography of IGAC. KEY WORDS: vertical accuracy assessment; digital terrain model; digital elevation model
An Assessment of Digital Elevation Models (DEMs) From Different Spatial Data Sources
Digital Elevation Model (DEM) represents a very important geospatial data type in the analysis and modelling of different hydrological and ecological phenomenon which are required in preserving our immediate environment. DEMs are typically used to represent terrain relief. DEMs are particularly relevant for many applications such as lake and water volumes estimation, soil erosion volumes calculations, flood estimate, quantification of earth materials to be moved for channels, roads, dams, embankment etc.
Evaluation of the Accuracy of Digital Elevation Model Produced from Different Open Source Data
Journal of Engineering, 2019
This study aims to estimate the accuracy of digital elevation models (DEM) which are created with exploitation of open source Google Earth data and comparing with the widely available DEM datasets, Shuttle Radar Topography Mission (SRTM), version 3, and Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM), version 2. The GPS technique is used in this study to produce digital elevation raster with a high level of accuracy, as reference raster, compared to the DEM datasets. Baghdad University, Al Jadriya campus, is selected as a study area. Besides, 151 reference points were created within the study area to evaluate the results based on the values of RMS. Furthermore, the Geographic Information System (GIS) was utilized to analyze, imagine and interpolate data in this study. The result of the statistical analysis revealed that RMSE of DEM related to the differences between the reference points and Google Earth, SRTM DEM and ASTER GDEM are 6.9, 5.5 and 4.8, respectively. What is more, a finding of this study shows convergence the level of accuracy for all open sources used in this study.
Digital elevation model (DEM) is a digital representation of ground surface topography and have been used in various applications. The introduction of global coverage DEM available for free or at reasonable cost was a new phenomenon in mapping. The issue is how accurate are these datasets and can it be used for topographic mapping. This paper aims to evaluate the height accuracy of DEMs generated from different sources. Results presented in this paper is part of a study to evaluate the suitable use of different DEMs and high resolution imagery for topographic map updating. For this paper, Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM), Intermap Airborne Interferometric Synthetic Aperture Radar Digital Terrain Model (IFSAR DTM), IFSAR Digital Surface Model (IFSAR DSM), digital topographic map (with a 5m contour interval) and Light Detection and Ranging (LiDAR) datasets are used to generate the contours, height points and height profiles. LiDAR dataset is used as reference DEM to evaluate the accuracy of NEXTMap IFSAR DTM and Digital Terrain Model (DTM) generated from digital topographic maps acquired from the Department of Survey and Mapping Malaysia. The vertical accuracy of ASTER GDEM is obtained by comparing wih the heights of IFSAR DSM. The Root Mean Squares Error (RMSE) of the height points generated from IFSAR DTM and digital topographic map of the non-vegetated areas within the study area are 1.458 m and 2.960 m respectively. For the vegetated area, the RMSE of IFSAR DTM and digital topographic map are 4.736 m and 9.848 m respectively. The accuracy of ASTER GDEM in the vegetated and non-vegetated areas are 8.442 m and 18.900 m respectively. Visual comparison between the contours generated from IFSAR DTM and LiDAR has shown promising result. ASTER GDEM can be used to capture the general characteristic of the terrain. Future work will include the evaluation of factors that contribute to the accuracy of DEMs generated from different sources.