scholarly journals EVALUATION OF ASTER GDEM V3 USING ICESAT LASER ALTIMETRY

2016 ◽  
Vol XLI-B4 ◽  
pp. 117-124
Author(s):  
C. C. Carabajal ◽  
J.-P. Boy
Keyword(s):  
Thermal Emission ◽  
Ground Control ◽  
Control Points ◽  
Ice Cloud ◽  
Aster Gdem ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Elevation Model ◽  
Globally Distributed

We have used a set of Ground Control Points (GCPs) derived from altimetry measurements from the Ice, Cloud and land Elevation Satellite (ICESat) to evaluate the quality of the 30 m posting ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) Global Digital Elevation Model (GDEM) V3 elevation products produced by NASA/METI for Greenland and Antarctica. These data represent the highest quality globally distributed altimetry measurements that can be used for geodetic ground control, selected by applying rigorous editing criteria, useful at high latitudes, where other topographic control is scarce. Even if large outliers still remain in all ASTER GDEM V3 data for both, Greenland and Antarctica, they are significantly reduced when editing ASTER by number of scenes (N≥5) included in the elevation processing. For 667,354 GCPs in Greenland, differences show a mean of 13.74 m, a median of -6.37 m, with an RMSE of 109.65 m. For Antarctica, 6,976,703 GCPs show a mean of 0.41 m, with a median of -4.66 m, and a 54.85 m RMSE, displaying smaller means, similar medians, and less scatter than GDEM V2. Mean and median differences between ASTER and ICESat are lower than 10 m, and RMSEs lower than 10 m for Greenland, and 20 m for Antarctica when only 9 to 31 scenes are included.

scholarly journals EVALUATION OF ASTER GDEM V3 USING ICESAT LASER ALTIMETRY

2016 ◽  
Vol XLI-B4 ◽  
pp. 117-124 ◽  
Author(s):  
C. C. Carabajal ◽  
J.-P. Boy
Keyword(s):  
Thermal Emission ◽  
Ground Control ◽  
Control Points ◽  
Ice Cloud ◽  
Aster Gdem ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Elevation Model ◽  
Globally Distributed

We have used a set of Ground Control Points (GCPs) derived from altimetry measurements from the Ice, Cloud and land Elevation Satellite (ICESat) to evaluate the quality of the 30 m posting ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) Global Digital Elevation Model (GDEM) V3 elevation products produced by NASA/METI for Greenland and Antarctica. These data represent the highest quality globally distributed altimetry measurements that can be used for geodetic ground control, selected by applying rigorous editing criteria, useful at high latitudes, where other topographic control is scarce. Even if large outliers still remain in all ASTER GDEM V3 data for both, Greenland and Antarctica, they are significantly reduced when editing ASTER by number of scenes (N≥5) included in the elevation processing. For 667,354 GCPs in Greenland, differences show a mean of 13.74 m, a median of -6.37 m, with an RMSE of 109.65 m. For Antarctica, 6,976,703 GCPs show a mean of 0.41 m, with a median of -4.66 m, and a 54.85 m RMSE, displaying smaller means, similar medians, and less scatter than GDEM V2. Mean and median differences between ASTER and ICESat are lower than 10 m, and RMSEs lower than 10 m for Greenland, and 20 m for Antarctica when only 9 to 31 scenes are included.

scholarly journals Digital elevation model validation with no ground control: application to the topodata dem in Brazil

2014 ◽  
Vol 20 (2) ◽  
pp. 467-479 ◽  
Author(s):  
Laurent Polidori ◽  
Mhamad El Hage ◽  
Márcio De Morisson Valeriano
Keyword(s):  
Digital Elevation Model ◽  
Visual Analysis ◽  
Ground Control ◽  
Ground Control Points ◽  
Geostatistical Approach ◽  
Digital Elevation ◽  
Elevation Model ◽  
Control Application ◽  
Statistical Indicators

Digital Elevation Model (DEM) validation is often carried out by comparing the data with a set of ground control points. However, the quality of a DEM can also be considered in terms of shape realism. Beyond visual analysis, it can be verified that physical and statistical properties of the terrestrial relief are fulfilled. This approach is applied to an extract of Topodata, a DEM obtained by resampling the SRTM DEM over the Brazilian territory with a geostatistical approach. Several statistical indicators are computed, and they show that the quality of Topodata in terms of shape rendering is improved with regards to SRTM.

scholarly journals 3-D modelling and visualization of large building using photogrammetric approach

2021 ◽  
Author(s):  
Raad Awad Kattan ◽  
◽  
Farsat Heeto Abdulrahman ◽  
Sami Mamlook Gilyana ◽  
Yousif Youkhna Zaya ◽  
...  
Keyword(s):  
Bundle Adjustment ◽  
Ground Control ◽  
Control Points ◽  
Distance Measurements ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Elevation Model ◽  
College Of Engineering ◽  
User Friendly ◽  
D Model

The progress in modern technologies such as precise lightweight cameras mounted on unmanned aerial vehicles (UAV) and the more user-friendly software in the photogrammetric field, allows for 3-D model construction of any structure or shape. Software now achieves in sequence the processes of matching, generating tie points, block bundle adjustment, and generating digital elevation models.The aim of this study is to make a virtual 3-D model of the college of engineering /University of Duhok. Kurdistan Region, Iraq. The data input is vertical and oblique imagery acquired by UAV, ground control points distributed on the surrounded ground, facades, and roof. Ground control points were measured by the GPS RTK system in addition to the reflectorless total station instrument. The data is processed mainly using Agisoft PhotoScan software as well as the Global Mapper and the ReCap software. The output is a 3-D model, digital elevation model, and orthomosaic.Geometric and visual inspections were carried out. Some imperfections appeared on the sharp edges and parapets of the building. In the geometric accuracy of selected points on the building, the maximum standard deviation in the coordinates was ±4cm. The relative accuracy in distance measurements were in the range of 0.72% to 4.92 %

scholarly journals Comparison of Digital Elevation Models for the designing water reservoirs: a case study Pskom water reservoir

2021 ◽  
Vol 264 ◽  
pp. 03058
Author(s):  
Khojiakbar Khasanov ◽  
Azamat Ahmedov
Keyword(s):  
Water Reservoir ◽  
Vertical Axis ◽  
Ground Control ◽  
Control Points ◽  
Alos Palsar ◽  
Aster Gdem ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Vertical Accuracy

This study investigates the accuracy of various DEMs (SRTM DEM, ASTER GDEM, and ALOS PALSAR DEM) for the area of the designing Pskom water reservoir (recommended to construction in Pskom River, in Tashkent region. DEMs are compared for the study area using the Global Mapper application and selection Ground Control Points (GCP). The RMSE we calculate is the most easily interpreted statistic as the square root of the mean square error because it has the same units as the quantity drawn on the vertical axis. Results show that SRTM based measurements of ground control points (GCPs) exhibit RMSE of 15.72 m while ASTER DEM based measurements exhibits and RMSE of 18.47 m, ALOS PALSAR exhibit RMSE of 14.02 m for the Water reservoir located in the plain. There are AOS PALSAR outperforms SRTM and ASTER DEM in detecting vertical accuracy. Based on the capabilities of the Global Mapper program, we can build the longitudinal profile of the approximate location where the dam can be built in each DEM and compare. The results obtained show that the dam height is 187 m at ALOS PALSAR DEM, 168 m at ASTER GDEM, and 175 m at SRTM. The study found that using ALOS PALSAR data in the design of the proposed Pskom Reservoir for construction leads to a more accurate result. Comparing the DEMs data shows that there is more difference between the vertical accuracy; the horizontal accuracy level is almost the same. The results were obtained using ALOS PALSAR data in determining the storage volume (W=479368568 m3) and area (F=8.31 sq., km) of the water reservoir.

scholarly journals Structure-from-Motion on shallow reefs and beaches: potential and limitations of consumer-grade drones to reconstruct topography and bathymetry

Coral Reefs ◽  
2021 ◽  
Author(s):  
C. Gabriel David ◽  
Nina Kohl ◽  
Elisa Casella ◽  
Alessio Rovere ◽  
Pablo Ballesteros ◽  
...  
Keyword(s):  
Shallow Water ◽  
Structure From Motion ◽  
Water Levels ◽  
Aerial Photographs ◽  
Ground Control ◽  
Control Points ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Nonlinear Distortions ◽  
Elevation Model

AbstractReconstructing the topography of shallow underwater environments using Structure-from-Motion—Multi View Stereo (SfM-MVS) techniques applied to aerial imagery from Unmanned Aerial Vehicles (UAVs) is challenging, as it involves nonlinear distortions caused by water refraction. This study presents an experiment with aerial photographs collected with a consumer-grade UAV on the shallow-water reef of Fuvahmulah, the Maldives. Under conditions of rising tide, we surveyed the same portion of the reef in ten successive flights. For each flight, we used SfM-MVS to reconstruct the Digital Elevation Model (DEM) of the reef and used the flight at low tide (where the reef is almost entirely dry) to compare the performance of DEM reconstruction under increasing water levels. Our results show that differences with the reference DEM increase with increasing depth, but are substantially larger if no underwater ground control points are taken into account in the processing. Correcting our imagery with algorithms that account for refraction did not improve the overall accuracy of reconstruction. We conclude that reconstructing shallow-water reefs (less than 1 m depth) with consumer-grade UAVs and SfM-MVS is possible, but its precision is limited and strongly correlated with water depth. In our case, the best results are achieved when ground control points were placed underwater and no refraction correction is used.

scholarly journals THE RATIONAL POLYNOMIAL COEFFICIENTS MODIFICATION USING DIGITAL ELEVATION MODELS

2015 ◽  
Vol XL-1-W5 ◽  
pp. 47-50 ◽  
Author(s):  
F. Alidoost ◽  
A. Azizi ◽  
H. Arefi
Keyword(s):  
Point Cloud ◽  
Digital Elevation Models ◽  
Ground Control ◽  
Control Points ◽  
Polynomial Coefficients ◽  
Ground Control Points ◽  
Rational Polynomial ◽  
Digital Elevation ◽  
Elevation Model ◽  
Parameters Calculation

The high-resolution satellite imageries (HRSI) are as primary dataset for different applications such as DEM generation, 3D city mapping, change detection, monitoring, and deformation detection. The geo-location information of HRSI are stored in metadata called Rational Polynomial Coefficients (RPCs). There are many methods to improve and modify the RPCs in order to have a precise mapping. In this paper, an automatic approach is presented for the RPC modification using global Digital Elevation Models. The main steps of this approach are: relative digital elevation model generation, shift parameters calculation, sparse point cloud generation and shift correction, and rational polynomial fitting. Using some ground control points, the accuracy of the proposed method is evaluated based on statistical descriptors in which the results show that the geo-location accuracy of HRSI can be improved without using Ground Control Points (GCPs).

scholarly journals Using Photogrammetric UAV Measurements as Support for Classical Topographical Measurements in Order to Obtain the Topographic Plan for Urban Areas

2017 ◽  
Vol 74 (2) ◽  
pp. 197
Author(s):  
Elemer Emanuel SUBA ◽  
Tudor SĂLĂGEAN ◽  
Ioana POP ◽  
Florica MATEI ◽  
Jutka DEAK ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Urban Areas ◽  
Point Cloud ◽  
Ground Control ◽  
Control Points ◽  
Ground Control Points ◽  
Triangulation Network ◽  
Digital Elevation ◽  
Photogrammetric Method ◽  
Elevation Model

This article aims to highlight the benefits of UAV photogrammetric measurements in addition to classical ones. It will also deal with the processing and integration of the point cloud, respectively the digital elevation model in topo-cadastral works. The main purpose of this paper is to compare the results obtained using the UAV photogrammetric measurements with the results obtained by classical methods. It will briefly present the classical measurements made with the total station. In the present project, the closed-circuit traverse and the supported on the endings traverse were made using known coordinate points. Determining the coordinates of the points used for the traverses was done by GNSS methods. The area on which the measurements were made is 67942m2 and is covered by 31 determined station points. From these points, 13 were used as ground control points, respectively components of the aero-triangulation network and 17 points were used to control the obtained results by comparing their coordinates obtained by classical methods with those obtained by the UAV photogrammetric method. It was intended that the constraint points of the aero triangulation to be uniformly distributed on the studied surface.

scholarly journals Accuracy of 3D Landscape Reconstruction without Ground Control Points Using Different UAS Platforms

Drones ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 13 ◽  
Author(s):  
Margaret Kalacska ◽  
Oliver Lucanus ◽  
J. Pablo Arroyo-Mora ◽  
Étienne Laliberté ◽  
Kathryn Elmer ◽  
...  
Keyword(s):  
Low Cost ◽  
Ground Control ◽  
Unmanned Aerial Systems ◽  
Control Points ◽  
Model Errors ◽  
Positional Accuracy ◽  
Ground Control Points ◽  
Digital Elevation ◽  
High Level ◽  
Aerial Systems

The rapid increase of low-cost consumer-grade to enterprise-level unmanned aerial systems (UASs) has resulted in the exponential use of these systems in many applications. Structure from motion with multiview stereo (SfM-MVS) photogrammetry is now the baseline for the development of orthoimages and 3D surfaces (e.g., digital elevation models). The horizontal and vertical positional accuracies (x, y and z) of these products in general, rely heavily on the use of ground control points (GCPs). However, for many applications, the use of GCPs is not possible. Here we tested 14 UASs to assess the positional and within-model accuracy of SfM-MVS reconstructions of low-relief landscapes without GCPs ranging from consumer to enterprise-grade vertical takeoff and landing (VTOL) platforms. We found that high positional accuracy is not necessarily related to the platform cost or grade, rather the most important aspect is the use of post-processing kinetic (PPK) or real-time kinetic (RTK) solutions for geotagging the photographs. SfM-MVS products generated from UAS with onboard geotagging, regardless of grade, results in greater positional accuracies and lower within-model errors. We conclude that where repeatability and adherence to a high level of accuracy are needed, only RTK and PPK systems should be used without GCPs.

scholarly journals Glacier topography and elevation changes from Pléiades very high resolution stereo images

2014 ◽  
Vol 8 (5) ◽  
pp. 4849-4883 ◽  
Author(s):  
E. Berthier ◽  
C. Vincent ◽  
E. Magnússon ◽  
Á. Þ. Gunnlaugsson ◽  
P. Pitte ◽  
...  
Keyword(s):  
Field Measurements ◽  
Ground Control ◽  
European Alps ◽  
Control Points ◽  
Mass Balances ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Stereo Imagery ◽  
Elevation Changes ◽  
Very High

Abstract. In response to climate change, most glaciers are losing mass and hence contribute to sea-level rise. Repeated and accurate mapping of their surface topography is required to estimate their mass balance and to extrapolate/calibrate sparse field glaciological measurements. In this study we evaluate the potential of Pléiades sub-meter stereo imagery to derive digital elevation models (DEMs) of glaciers and their elevation changes. Our five validation sites are located in Iceland, the European Alps, the Central Andes, Nepal and Antarctica. For all sites, nearly simultaneous field measurements were collected to evaluate the Pléiades DEMs. For Iceland, the Pléiades DEM is also compared to a Lidar DEM. The vertical biases of the Pléiades DEMs are less than 1 m if ground control points (GCPs) are used, but reach up to 6 m without GCPs. Even without GCPs, vertical biases can be reduced to a few decimetres by horizontal and vertical co-registration of the DEMs to reference altimetric data on ice-free terrain. Around these biases, the vertical precision of the Pléiades DEMs is ±1 m and even ±0.5 m on the flat glacier tongues (1-sigma confidence level). We also demonstrate the high potential of Pléiades DEMs for measuring seasonal, annual and multi-annual elevation changes with an accuracy of 1 m or better. The negative glacier-wide mass balances of the Argentière Glacier and Mer de Glace (−1.21 ± 0.16 and −1.19 ± 0.16 m.w.e. yr−1, respectively) are revealed by differencing SPOT5 and Pléiades DEMs acquired in August 2003 and 2012 demonstrating the continuing rapid glacial wastage in the Mont-Blanc area.

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