Vertical accuracy assessment for SRTM and ASTER Digital Elevation Models: A case study of Najran city, Saudi Arabia

Abstract This paper presents a comparative study between the absolute and relative methods for altimetric positional accuracy of Digital Elevation Models (DEM). For the theoretical basis of this research, the definitions of accuracy (exactness) and precision, as well the concepts related to absolute and relative positional accuracy were explored. In the case study, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and the Shuttle Radar Topography Mission (SRTM) DEM were used. In the analysis of the absolute accuracy, 6,568 ground control points from GNSS orbital survey were used, collected through relative-static method. In the relative accuracy, it was used as reference DEM with spatial resolution of 5 meters generated by stereophotogrammetrical process for the Mapping Project of Bahia (Brazil). It was concluded that, once the accuracy of the reference DEM is better than the other two evaluated DEM, the results of the classification for the PEC-PCD for the relative evaluation are equal to or better than the absolute evaluation results, with the advantage to being able to verify the pixel population of the evaluated models, which makes it possible to identify outliers, distortions and displacements, including delimiting regions, which is much less likely with a limited set of control points.

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Avaliação da Acurácia Vertical dos Modelos Digitais de Elevação SRTM, ALOS World 3D e ASTER GDEM: Um Estudo de Caso no Vale dos Vinhedos, RS – Brasil

Revista Brasileira de Geografia Física ◽

10.26848/rbgf.v13.5.p2255-2268 ◽

2020 ◽

Vol 13 (5) ◽

pp. 2255

Author(s):

Jorge Antônio Viel ◽

Kátia Kellem da Rosa ◽

Cláudio Wilson Mendes Junior

Keyword(s):

Spatial Resolution ◽

Digital Elevation Models ◽

Pearson Correlation ◽

Mean Square ◽

Class A ◽

Aster Gdem ◽

Digital Elevation ◽

The Mean ◽

Vertical Accuracy

Este estudo tem como objetivo avaliar a acurácia vertical dos Modelos Digitais de Elevação (MDEs) SRTM v.3, ALOS World 3D e ASTER GDEM v.2 na região da denominação de origem Vale dos Vinhedos, RS. Para tanto, os dados desses MDEs, com resolução espacial de 30 m, foram comparados com os de um MDE fotogramétrico com resolução espacial de 5 m no terreno, por meio de análises de regressão e correlação linear, e de perfis topográficos derivados desses modelos. O Padrão de Exatidão Cartográfica dos Produtos Cartográficos Digitais (PEC-PCD) de cada MDE foi analisado, para identificar a escala máxima de seu uso em estudos morfométricos, nas escalas 1:25.000, 1:50.000 e 1:100.000, por meio de cálculos da Tolerância Vertical e do Erro Médio Quadrático (EMQ). Os MDEs SRTM v.3 e ASTER GDEM v.2 atenderam o PEC-PCD altimétrico classe A na escala 1:100.000. Diferentemente do MDE ALOS World 3D que enquadrou-se na classe B para a escala de 1:100.000. Todos os modelos, na escala 1:50.000, enquadraram-se na classe D, enquanto que na escala 1:25.000 não houve enquadramento. O MDE SRTM v.3 foi o que apresentou melhores resultados morfométricos e o maior coeficiente de correlação de Pearson (r=0,995). Todos os MDEs avaliados neste estudo apresentaram morfologia próxima a do MDE fotogramétrico. Portanto, recomenda-se o uso de todos os MDEs analisados em estudos morfométricos da área de estudo, sendo necessário observar o objetivo do trabalho, bem como a escala de análise e a apresentação desses dados. Evaluation of the Vertical Acuracy of Digital Elevation Models SRTM, ALOS WORLD 3D and ASTER GDEM: a case study in Vale dos Vinhedos, RS - Brazil A B S T R A C TThis work aims to evaluate the vertical accuracy of the digital elevation models (DEMs) SRTM v.3, Alos World 3D and ASTER GDEM v.2 in Vale dos Vinhedos designation of origin (DO) region, RS. Thus, the DEM data with 30 m of the spatial resolution were compared with photogrammetric DEM data with 5 m of the spatial resolution by linear regression and correlation analyzes, and also, topographic profiles carried out with these models. The Cartographic Accuracy Standard (PEC) of each DEM was analyzed to identify the maximum scale for morphometric application, in scales 1:25.000, 1:50.000 and 1:100.000, by calculations of Vertical Tolerance and the Mean Square Error (MSE). All DEMs. All the models studied were classified in class A for the 1:100,000 scale, and for the 1:50,000 scale the analyzed models were classified in class C, while in 1:25.000 scale doesn´t have application. The DEM SRTM v.3 presented smaller altimetry errors compared to ASTER GDEM and Alos World 3D, as for mophometric analysis and Pearson correlation coefficient (r=0,995). It is worth mentioning that all models analyzed are statistically and morphologically close. Therefore, they can be used to conduct several studies, however it is necessary to have in mind the goal of the work, and the scale of analysis and presentation.Keywords: Vertical accuracy, SRTM v.3, Alos World 3D, ASTER GDEM

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