Analysis on Spatial Distribution of Check Points for Vertical Accuracy Assessment of DTM derived from UAV

2018 ◽  
Author(s):  
Fatwa Ramdani ◽  
Budi Darma Setiawan ◽  
Alfi Nur Rusydi ◽  
M. Tanzil Furqon ◽  
Andy Gusty Rangga ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Accuracy Assessment ◽  
Check Points ◽  
Vertical Accuracy

scholarly journals Geometric Accuracy Assessment of Deimos-2 Panchromatic Stereo Pairs: Sensor Orientation and Digital Surface Model Production

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7234
Author(s):  
Manuel A. Aguilar ◽  
Rafael Jiménez-Lao ◽  
Abderrahim Nemmaoui ◽  
Fernando J. Aguilar
Keyword(s):  
Urban Areas ◽  
Satellite Images ◽  
Accuracy Assessment ◽  
Bare Soil ◽  
Surface Model ◽  
Stereo Pair ◽  
Rational Polynomial ◽  
Sensor Orientation ◽  
Vertical Accuracy ◽  
Land Covers

Accurate elevation data, which can be extracted from very high-resolution (VHR) satellite images, are vital for many engineering and land planning applications. In this way, the main goal of this work is to evaluate the capabilities of VHR Deimos-2 panchromatic stereo pairs to obtain digital surface models (DSM) over different land covers (bare soil, urban and agricultural greenhouse areas). As a step prior to extracting the DSM, different orientation models based on refined rational polynomial coefficients (RPC) and a variable number of very accurate ground control points (GCPs) were tested. The best sensor orientation model for Deimos-2 L1B satellite images was the RPC model refined by a first-order polynomial adjustment (RPC1) supported on 12 accurate and evenly spatially distributed GCPs. Regarding the Deimos-2 based DSM, its completeness and vertical accuracy were compared with those obtained from a WorldView-2 panchromatic stereo pair by using exactly the same methodology and semiglobal matching (SGM) algorithm. The Deimos-2 showed worse completeness values (about 6% worse) and vertical accuracy results (RMSEZ 42.4% worse) than those computed from WorldView-2 imagery over the three land covers tested, although only urban areas yielded statistically significant differences (p < 0.05).

scholarly journals A new 100-m Digital Elevation Model of the Antarctic Peninsula derived from ASTER Global DEM: methods and accuracy assessment

2012 ◽  
Vol 4 (1) ◽  
pp. 129-142 ◽  
Author(s):  
A. J. Cook ◽  
T. Murray ◽  
A. Luckman ◽  
D. G. Vaughan ◽  
N. E. Barrand
Keyword(s):  
Digital Elevation Model ◽  
Antarctic Peninsula ◽  
Accuracy Assessment ◽  
Correction Method ◽  
Pixel Size ◽  
Aster Gdem ◽  
Digital Elevation ◽  
Vertical Accuracy ◽  
Elevation Model ◽  
The Antarctic

Abstract. A high resolution surface topography Digital Elevation Model (DEM) is required to underpin studies of the complex glacier system on the Antarctic Peninsula. A complete DEM with better than 200 m pixel size and high positional and vertical accuracy would enable mapping of all significant glacial basins and provide a dataset for glacier morphology analyses. No currently available DEM meets these specifications. We present a new 100-m DEM of the Antarctic Peninsula (63–70° S), based on ASTER Global Digital Elevation Model (GDEM) data. The raw GDEM products are of high-quality on the rugged terrain and coastal-regions of the Antarctic Peninsula and have good geospatial accuracy, but they also contain large errors on ice-covered terrain and we seek to minimise these artefacts. Conventional data correction techniques do not work so we have developed a method that significantly improves the dataset, smoothing the erroneous regions and hence creating a DEM with a pixel size of 100 m that will be suitable for many glaciological applications. We evaluate the new DEM using ICESat-derived elevations, and perform horizontal and vertical accuracy assessments based on GPS positions, SPOT-5 DEMs and the Landsat Image Mosaic of Antarctica (LIMA) imagery. The new DEM has a mean elevation difference of −4 m (&amp;pm; 25 m RMSE) from ICESat (compared to −13 m mean and &amp;pm;97 m RMSE for the original ASTER GDEM), and a horizontal error of less than 2 pixels, although elevation accuracies are lower on mountain peaks and steep-sided slopes. The correction method significantly reduces errors on low relief slopes and therefore the DEM can be regarded as suitable for topographical studies such as measuring the geometry and ice flow properties of glaciers on the Antarctic Peninsula. The DEM is available for download from the NSIDC website: http://nsidc.org/data/nsidc-0516.html (doi:10.5060/D47P8W9D).

scholarly journals Accuracy Assessment of Digital Terrain Model Datasets Sources for Hydrogeomorphological Modelling at Mediterranean Catchments

2018 ◽  
Author(s):  
Lukas Graf ◽  
Mariano Moreno-de las Heras ◽  
Maurici Ruiz ◽  
Josep Fortesa ◽  
Aleix Calsamiglia ◽  
...  
Keyword(s):  
Mean Squared Error ◽  
Accuracy Assessment ◽  
Digital Terrain Model ◽  
Airborne Lidar ◽  
Stream Network ◽  
Terrain Model ◽  
Human Land Use ◽  
Aster Gdem ◽  
Digital Terrain ◽  
Vertical Accuracy

Digital Terrain Models (DTMs) are currently a fundamental source of information in Earth Sciences. However, DTM-based studies can contain remarkable biases if limitations and inaccuracies of these models are disregarded. In this work, four freely available datasets such as SRTM C-SAR DEM, ASTER GDEM V2 and two airborne LiDAR derived DTMs (at 5 and 1 m spatial resolution, respectively) were analysed in a comparative study in three geomorphologically contrasted catchments located in Mediterranean geoecosystems under intensive human land use influence. Vertical accuracy as well as the influence of each dataset characteristics on hydrological and geomorphological modelling applicability were assessed by using classic geometric and morphometric parameters and the more recently proposed index of sediment connectivity. Overall vertical accuracy &ndash; expressed as Root Mean Squared Error (RMSE) and Normalized Median Deviation (NMAD) &ndash; revealed the highest accuracy in the cases of the 1 m (RMSE = 1.55 m; NMAD = 0.44 m) and 5 m LiDAR DTMs (RMSE = 1.73 m; NMAD = 0.84 m). Vertical accuracy of SRTM was lower (RMSE = 6.98 m; NMAD = 5.27 m) but considerably higher than in the case of ASTER (RMSE = 16.10 m; NMAD = 11.23 m). All datasets were affected by systematic distortions. As a consequence, propagation of these errors caused negative impacts on flow routing, stream network and catchment delineation and, to a lower extent, on the distribution of slope values. These limitations should be carefully considered when applying DTMs for hydrogeomorphological modelling.

scholarly journals Comparison of Vertical Accuracy of Open-Source Global Digital Elevation Models: A Case Study of Adama City, Ethiopia

2021 ◽  
Vol 12 (4) ◽  
pp. 1731-1744
Author(s):  
Hailu Zewde Abili
Keyword(s):  
Open Source ◽  
Thermal Emission ◽  
Accuracy Assessment ◽  
Shuttle Radar Topography Mission ◽  
Surface Model ◽  
Aster Gdem ◽  
Digital Elevation ◽  
Wide Range ◽  
Vertical Accuracy ◽  
Elevation Model

DEM can be generated from a wide range of sources including land surveys, Photogrammetry, and Remote sensing satellites. SRTM 30m DEM by The Shuttle Radar Topography Mission (SRTM), the Global Digital Elevation Model by Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER GDEM) and a global surface model called ALOS Worldview 3D 30 meter (AW3D30) by Advanced Land Observing Satellite (ALOS) are satellite-based global DEMs open-source DEM datasets. This study aims to assess the vertical accuracy of ASTER GDEM2, SRTM 30m, and ALOS (AW3D30) global DEMs over Ethiopia in the study area-Adama by using DGPS points and available accurate reference DEM data. The method used to evaluate the vertical accuracy of those DEMs ranges from simple visual comparison to relative and absolute comparisons providing quantitative assessment (Statistical) that used the elevation differences between DEM datasets and reference datasets. The result of this assessment showed better accuracy of SRTM 30m DEM (having RMSE of ± 4.63 m) and closely followed by ALOS (AW3D30) DEM which scored RMSE of ± 5.25 m respectively. ASTER GDEM 2 showed the least accuracy by scoring RMSE of ± 11.18 m in the study area. The second accuracy assessment was done by the analysis of derived products such as slope and drainage networks. This also resulted in a better quality of DEM derived products for SRTM than ALOS DEM and ASTER GDEM.

scholarly journals Study of NSSDA Variability by Means of Automatic Positional Accuracy Assessment Methods

2019 ◽  
Vol 8 (12) ◽  
pp. 552 ◽  
Author(s):  
Juan José Ruiz-Lendínez ◽  
Francisco Javier Ariza-López ◽  
Manuel Antonio Ureña-Cámara
Keyword(s):  
Theoretical Analysis ◽  
Sample Size ◽  
Spatial Data ◽  
Graphical Representation ◽  
Accuracy Assessment ◽  
Experimental Tests ◽  
National Standard ◽  
Positional Accuracy ◽  
Check Points ◽  
Spatial Dataset

Point-based standard methodologies (PBSM) suggest using ‘at least 20’ check points in order to assess the positional accuracy of a certain spatial dataset. However, the reason for decreasing the number of checkpoints to 20 is not elaborated upon in the original documents provided by the mapping agencies which develop these methodologies. By means of theoretical analysis and experimental tests, several authors and studies have demonstrated that this limited number of points is clearly insufficient. Using the point-based methodology for the automatic positional accuracy assessment of spatial data developed in our previous study Ruiz-Lendínez, et al (2017) and specifically, a subset of check points obtained from the application of this methodology to two urban spatial datasets, the variability of National Standard for Spatial Data Accuracy (NSSDA) estimations has been analyzed according to sample size. The results show that the variability of NSSDA estimations decreases when the number of check points increases, and also that these estimations have a tendency to underestimate accuracy. Finally, the graphical representation of the results can be employed in order to give some guidance on the recommended sample size when PBSMs are used.

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