Evaluation Of Digital Elevation Models Research Articles

Сравнение цифровых моделей рельефа

Introduction. GIS technologies make it possible to analyze large amounts of spatial data, which include digital elevation models derived from remote sensing data. They are an important source of data for calculating and mapping various phenomena and processes that are closely interrelated with the relief, and cover vast areas. The article presents the results of the accuracy assessment of the three most popular global digital elevation models: ALOS World 3D, SRTM, and ASTER. Materials and research methods. The evaluation of digital elevation models was carried out on the territory of Budennovsky urban district of Stavropol Krai. Error analysis of morphometric indicators was performed based on the comparison of the studied digital elevation models and the data of the State Research and Development Center of Geoformation Systems and Technologies – GosGisCenter, which were presented in the form of topographic maps. The analysis of the results of the study was carried out based on mathematical and statistical methods. The total sample of compared points equals 5322. Research results and their discussion. Based on the obtained dataset of each of the digital terrain models, a comparative analysis of the samples was carried out. As a result, it was determined that the ASTER model showed the lowest accuracy. SRTM project data showed insignificant deviations. The digital terrain model based on ALOS W3D data has the highest accuracy. Conclusions. Despite its popularity and at first glance similarity of the data, a number of features of each of the digital terrain models were identified. The data obtained will simplify the selection of a digital terrain model, taking into account the requirements needed to perform various tasks, as well as improve the accuracy of the results obtained.

Accuracy evaluation of digital elevation models derived from Terrestrial Radar Interferometer over Helheim Glacier, Greenland

Glaciers in polar regions are sensitive to climate and ocean changes and can thin rapidly as a consequence of global warming. Digital Elevation Models (DEMs) from remote sensing observations have been widely used to detect changes in polar glaciers. DEMs from Terrestrial Radar Interferometer (TRI) have recently been used for high frequency glacier change and glacier-ocean interaction studies. However, it is unclear whether TRI DEM over a large study area can be combined directly with remote sensing observations to investigate glacier changes as well as the accuracy of TRI DEM at far range. In this study, we deployed a TRI close to Helheim Glacier, East Greenland and generated DEMs using TRI and satellite laser altimetry. We analyzed the accuracy of the TRI DEM using theoretical calculations, comparisons based on repeat observations, and comparisons with a high accurate ArcticDEM. The validation results suggest that for stable ground surfaces, the uncertainty (standard deviation) is <5 m at range < 9.8 km. Averaging across time (e.g. one hour) decreases the uncertainty almost linearly with range, over 0.5 m to 1.2 m when the range increases from 7.0 km to 10.0 km. Increasing the correlation coefficient threshold for phase unwrapping does not significantly reduce uncertainty. TRI DEMs are influenced by systematic error at far range primarily due to coarse azimuth resolution and phase unwrapping difficulties in discontinuous interferograms. As the absolute accuracy of TRI DEMs is not uniformly distributed in the range direction (farther points have worse uncertainty), our findings indicate that TRI DEMs within range of 10 km can reach <5 m uncertainty, which can be compared with DEMs obtained from remote sensing satellites to detect glacier thinning.

Evaluation of Digital Elevation Models Derived from Multi-Date Satellite Stereo Imagery for Urban Areas

High-resolution digital elevation models of urban areas can support humanitarian organisations in their work; especially the 3D reconstruction of buildings is desirable because it can be used for population estimation and damage analysis after crises and disaster events. In this paper, we test the quality of multi-date DEMs with 15 Pléiades images from Port-au-Prince, Haiti using the automatic stereo pipeline s2p. We focus on triplet combinations with images taken from different dates. This study investigates the meta-parameters satellite azimuth and incident angle to understand which recording geometry yields a good result in terms of completeness and accuracy. It is assumed that the closer the multi-date constellation gets to an in-orbit triplet, the better the quality of the DEM.

The Accuracy Evaluation of Digital Elevation Models for Forest Areas Produced Under Different Filtering Conditions of Airborne LiDAR Raw Data

The Accuracy Evaluation of Digital Elevation Models for Forest Areas Produced Under Different Filtering Conditions of Airborne LiDAR Raw Data

Accuracy Evaluation of Digital Elevation Model Created Using Handheld Global Positioning System Receivers

This study aims to assess the accuracy of digital elevation model (DEM) created with utilization of handheld Global Positioning System (GPS) and comparing with Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM), version 2. It is known that the quality of the DEM is affected by both of accuracy of elevation at each pixel (absolute accuracy) and accuracy of presented morphology (relative accuracy). The University of Baghdad, Al Jadriya campus was selected as a study area to create and analysis the resulting DEM. Additionally, Geographic Information System (GIS) was used to visualize, analyses and interpolate GPS track points (elevation data) of the study area. In this research, three additional DEMs were created using 60%, 30% and 15% of the all GPS track points to deduce the effect of the number of the included points on the accuracy of the resulting DEM. The study findings show a high resolution for the resulting DEM less than 5m when taking into consideration all GPS tracking points that observed in this research. Moreover, the resulting DEM has relative accuracy better than absolute accuracy and reaches to around 2m. By comparing with ground control points (reference points), the quality of handheld GPS DEM shows considerable improvement better than ASTER GDEM. Thus, this study indicates to improve the accuracy level of handheld GPS DEM by about 40% with increasing the observed number of GPS track points to twice.&#x0D; &#x0D;

An evaluation of digital elevation models (DEMs) for delineating land components

Land component boundaries often coincide with transitions in environmental land properties such as soil, climate and biology. Image segmentation is an effective method for delineating terrain morphological units from digital elevation models (DEMs). This paper compares the land components derived from five DEMs. The second version of the 30-m advanced spaceborne thermal emission and reflection radiometer global DEM (ASTER GDEM2), the 90-m shuttle radar topography mission DEM (SRTM DEM), two versions of the 5-m Stellenbosch University DEMs (SUDEM L1 and L2) and a 5-m DEM (GEOEYE DEM) derived from GeoEye stereo-images were considered. The SRTM DEM and the ASTER GDEM2 were upsampled to 5-m resolution for comparison purposes. Land components were delineated using the slope gradient and aspect derivatives of each DEM. The resulting land components were visually inspected and quantitatively analyzed using the slope gradient standard deviation (SGSD) measure and the mean slope gradient local variance (MSGLV) ratio. The results show that the GEOEYE DEM and SUDEM L2 yielded land components with relatively low SGSD values and that their boundaries often coincide with morphological discontinuities. The GEOEYE DEM produced land components with the highest MSGLV ratio, followed by SUDEM L2, ASTER GDEM2, SRTM DEM and SUDEM L1. Although the land components derived from SRTM DEM and SUDEM L1 were relatively homogeneous internally, their boundaries did not always trace morphological discontinuities. The ASTER GDEM2 failed to incorporate many of the morphological discontinuities in the study area. It is concluded that, although the SRTM DEM is more suitable than the ASTER GDEM2 for generating land components, higher-resolution DEMs such as the GEOEYE DEM and SUDEM L2 are required for delineating meaningful land components.

An Evaluation of Digital Elevation Models to Short-Term Monitoring of a High Energy Barrier Island, Northeast Brazil

The morphological short-term evolution of Ponta do Tubarao Island (PTI) was investigated through high accurate surveys based on post-processed kinematic (PPK) relative positioning on Global Navigation Satellite Systems (GNSS). PTI is part of a barrier island system on a high energy northeast Brazilian coastal environment and also an area of high environmental sensitivity. Surveys were carried out quarterly over a two years period from May 2010 to May 2012. This paper assesses statically the performance of digital elevation models (DEM) derived from different interpolation methods to represent morphologic features and to quantify volumetric changes and TIN models shown the best results to that purposes. The MDE allowed quantifying surfaces and volumes in detail as well as identifying the most vulnerable segments of the PTI to erosion and/or accumulation of sediments and relate the alterations to climate conditions. The coastal setting and geometry of PTI protects a significant mangrove ecosystem and some oil and gas facilities installed in the vicinities from damaging effects of strong oceanwaves and currents. Thus, the maintenance of PTI is extremely required but the prediction of its longevity is uncertain because results indicate an irregularity of sedimentary balance and a substantial decline in sediment supply to this coastal area

Remote sensing technology and geographic information system modeling: An integrated approach towards the mapping of groundwater potential zones in Hardrock terrain, Mamundiyar basin

In this paper, remote sensing, evaluation of digital elevation models (DEM), geographic information systems (GIS) and fieldwork techniques were combined to study the groundwater conditions in Mamundiyar basin, Tamilnadu. Several digital image processing techniques, including standard color composites, intensity-hue-saturation (IHS) transformation and decorrelation stretch (DS) were applied to map rock types. Remote sensing data were interpreted to produce lithological and lineament maps. DEM was used for lineament and geomorphologic mapping. All thematic layers were integrated and analyzed in a GIS. The overall results demonstrate that the use of remote sensing and GIS provide potentially powerful tools to study groundwater resources and design a suitable exploration plan.

Evaluation of digital elevation models for delineation of hydrological response units in a Himalayan watershed

This study reports results from evaluation of the quality of digital elevation model (DEM) from four sources viz. topographic map (1:50,000), Shuttle Radar Topographic Mission (SRTM) (90 m), optical stereo pair from ASTER (15 m) and CARTOSAT (2.5 m) and their use in derivation of hydrological response units (HRUs) in Sitla Rao watershed (North India). The HRUs were derived using water storage capacity and slope to produce surface runoff zones. The DEMs were evaluated on elevation accuracy and representation of morphometric features. The DEM derived from optical stereo pairs (ASTER and CARTOSAT) provided higher vertical accuracies than the SRTM and topographic map-based DEM. The SRTM with a coarse resolution of 90 m provided vertical accuracy but better morphometry compared to topographic map. The HRU maps derived from the fine resolution DEM (ASTER and CARTOSAT) were more detailed but did not provide much advantage for hydrological studies at the scale of Sitla Rao watershed (5800 ha).

Groundwater study using remote sensing and geographic information systems (GIS) in the central highlands of Eritrea

Remote sensing, evaluation of digital elevation models (DEM), geographic information systems (GIS) and fieldwork techniques were combined to study the groundwater conditions in Eritrea. Remote sensing data were interpreted to produce lithological and lineament maps. DEM was used for lineament and geomorphologic mapping. Field studies permitted the study of structures and correlated them with lineament interpretations. Hydrogeological setting of springs and wells were investigated in the field, from well logs and pumping test data. All thematic layers were integrated and analysed in a GIS. Results show that groundwater occurrence is controlled by lithology, structures and landforms. Highest yields occur in basaltic rocks and are due to primary and secondary porosities. High yielding wells and springs are often related to large lineaments, lineament intersections and corresponding structural features. In metamorphic and igneous intrusive rocks with rugged landforms, groundwater occurs mainly in drainage channels with valley fill deposits. Zones of very good groundwater potential are characteristic for basaltic layers overlying lateritized crystalline rocks, flat topography with dense lineaments and structurally controlled drainage channels with valley fill deposits. The overall results demonstrate that the use of remote sensing and GIS provide potentially powerful tools to study groundwater resources and design a suitable exploration plan.

Groundwater study using remote sensing and geographic information systems (GIS) in the central highlands of Eritrea

Remote sensing, evaluation of digital elevation models (DEM), geographic information systems (GIS) and fieldwork techniques were combined to study the groundwater conditions in Eritrea. Remote sensing data were interpreted to produce lithological and lineament maps. DEM was used for lineament and geomorphologic mapping. Field studies permitted the study of structures and correlated them with lineament interpretations. Hydrogeological setting of springs and wells were investigated in the field, from well logs and pumping test data. All thematic layers were integrated and analysed in a GIS. Results show that groundwater occurrence is controlled by lithology, structures and landforms. Highest yields occur in basaltic rocks and are due to primary and secondary porosities. High yielding wells and springs are often related to large lineaments, lineament intersections and corresponding structural features. In metamorphic and igneous intrusive rocks with rugged landforms, groundwater occurs mainly in drainage channels with valley fill deposits. Zones of very good groundwater potential are characteristic for basaltic layers overlying lateritized crystalline rocks, flat topography with dense lineaments and structurally controlled drainage channels with valley fill deposits. The overall results demonstrate that the use of remote sensing and GIS provide potentially powerful tools to study groundwater resources and design a suitable exploration plan.