Vertical accuracy evaluation of freely available latest high-resolution (30 m) global digital elevation models over Cameroon (Central Africa) with GPS/leveling ground control points.
Digital Elevation Models (DEMs) contain topographic relief data that are vital for many geoscience applications. This study relies on the vertical accuracy of publicly available latest high-resolution (30 m) global DEMs over Cameroon. These models are (1) the ALOS World 3D-30 m (AW3D30), (2) the Shu...
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| Format: | Article |
| Language: | English |
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Taylor & Francis Group
2019-05-01
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| Series: | International Journal of Digital Earth |
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| Online Access: | http://dx.doi.org/10.1080/17538947.2018.1458163 |
| _version_ | 1827811209114550272 |
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| author | Loudi Yap Ludovic Houetchak Kandé Robert Nouayou Joseph Kamguia Nasser Abdou Ngouh Marie Brigitte Makuate |
| author_facet | Loudi Yap Ludovic Houetchak Kandé Robert Nouayou Joseph Kamguia Nasser Abdou Ngouh Marie Brigitte Makuate |
| author_sort | Loudi Yap |
| collection | DOAJ |
| description | Digital Elevation Models (DEMs) contain topographic relief data that are vital for many geoscience applications. This study relies on the vertical accuracy of publicly available latest high-resolution (30 m) global DEMs over Cameroon. These models are (1) the ALOS World 3D-30 m (AW3D30), (2) the Shuttle Radar Topography Mission 1 Arc-Second C-Band Global DEM (SRTM 1) and (3) the Advanced Spaceborne Thermal Emission and Reflection Global DEM Version 2 (ASTER GDEM 2). After matching their coordinate systems and datums, the horizontal positional accuracy evaluation was carried out and it shows that geolocation errors significantly influence the vertical accuracy of global DEMs. After this, the three models are compared among them, in order to access random and systematic effects in the elevation data each of them contains. Further, heights from 555 GPS/leveling points distributed all over Cameroon are compared to each DEM, for their vertical accuracy determination. Traditional and robust statistical measures, normality test, outlier detection and removal were used to describe the vertical quality of the DEMs. The test of the normality rejected the hypothesis of normal distribution for all tested global DEMs. Overall vertical accuracies obtained for the three models after georeferencing and gross error removal in terms of Root Mean Square (RMS) and Normalized Median Absolute Deviation (NMAD) are: AW3D30 (13.06 m and 7.75 m), SRTM 1 (13.25 m and 7.41 m) and ASTER GDEM 2 (18.87 m and 13.30 m). Other accuracy measures (MED, 68.3% quantile, 95% quantile) supply some evidence of the good quality of AW3D30 over Cameroon. Further, the effect of land cover and slope on DEM vertical accuracy was also analyzed. All models have proved to be worse in the areas dominated by forests and shrubs areas. SRTM 1 and AW3D30 are more resilient to the effects of the scattering objects respectively in forests and cultivated areas. The dependency of DEMs accuracy on the terrain roughness is evident. In all slope intervals, AW3D30 is performing better than SRTM 1 and ASTER GDEM 2 over Cameroon. AW3D30 is more representative of the external topography over Cameroon in comparison with two others datasets and SRTM 1 can be a serious alternative to AW3D30 for a range of DEM applications in Cameroon. |
| first_indexed | 2024-03-11T23:02:02Z |
| format | Article |
| id | doaj.art-d62e1972102f4617bf8efc5e49e2327e |
| institution | Directory Open Access Journal |
| issn | 1753-8947 1753-8955 |
| language | English |
| last_indexed | 2024-03-11T23:02:02Z |
| publishDate | 2019-05-01 |
| publisher | Taylor & Francis Group |
| record_format | Article |
| series | International Journal of Digital Earth |
| spelling | doaj.art-d62e1972102f4617bf8efc5e49e2327e2023-09-21T14:38:07ZengTaylor & Francis GroupInternational Journal of Digital Earth1753-89471753-89552019-05-0112550052410.1080/17538947.2018.14581631458163Vertical accuracy evaluation of freely available latest high-resolution (30 m) global digital elevation models over Cameroon (Central Africa) with GPS/leveling ground control points.Loudi Yap0Ludovic Houetchak Kandé1Robert Nouayou2Joseph Kamguia3Nasser Abdou Ngouh4Marie Brigitte Makuate5National Institute of CartographyNational Institute of CartographyUniversity of Yaoundé 1National Institute of CartographyNational Institute of CartographyNational Institute of CartographyDigital Elevation Models (DEMs) contain topographic relief data that are vital for many geoscience applications. This study relies on the vertical accuracy of publicly available latest high-resolution (30 m) global DEMs over Cameroon. These models are (1) the ALOS World 3D-30 m (AW3D30), (2) the Shuttle Radar Topography Mission 1 Arc-Second C-Band Global DEM (SRTM 1) and (3) the Advanced Spaceborne Thermal Emission and Reflection Global DEM Version 2 (ASTER GDEM 2). After matching their coordinate systems and datums, the horizontal positional accuracy evaluation was carried out and it shows that geolocation errors significantly influence the vertical accuracy of global DEMs. After this, the three models are compared among them, in order to access random and systematic effects in the elevation data each of them contains. Further, heights from 555 GPS/leveling points distributed all over Cameroon are compared to each DEM, for their vertical accuracy determination. Traditional and robust statistical measures, normality test, outlier detection and removal were used to describe the vertical quality of the DEMs. The test of the normality rejected the hypothesis of normal distribution for all tested global DEMs. Overall vertical accuracies obtained for the three models after georeferencing and gross error removal in terms of Root Mean Square (RMS) and Normalized Median Absolute Deviation (NMAD) are: AW3D30 (13.06 m and 7.75 m), SRTM 1 (13.25 m and 7.41 m) and ASTER GDEM 2 (18.87 m and 13.30 m). Other accuracy measures (MED, 68.3% quantile, 95% quantile) supply some evidence of the good quality of AW3D30 over Cameroon. Further, the effect of land cover and slope on DEM vertical accuracy was also analyzed. All models have proved to be worse in the areas dominated by forests and shrubs areas. SRTM 1 and AW3D30 are more resilient to the effects of the scattering objects respectively in forests and cultivated areas. The dependency of DEMs accuracy on the terrain roughness is evident. In all slope intervals, AW3D30 is performing better than SRTM 1 and ASTER GDEM 2 over Cameroon. AW3D30 is more representative of the external topography over Cameroon in comparison with two others datasets and SRTM 1 can be a serious alternative to AW3D30 for a range of DEM applications in Cameroon.http://dx.doi.org/10.1080/17538947.2018.1458163demaw3d30srtm 1aster gdem 2cameroongps/levelingorthometric heightsvertical accuracy |
| spellingShingle | Loudi Yap Ludovic Houetchak Kandé Robert Nouayou Joseph Kamguia Nasser Abdou Ngouh Marie Brigitte Makuate Vertical accuracy evaluation of freely available latest high-resolution (30 m) global digital elevation models over Cameroon (Central Africa) with GPS/leveling ground control points. International Journal of Digital Earth dem aw3d30 srtm 1 aster gdem 2 cameroon gps/leveling orthometric heights vertical accuracy |
| title | Vertical accuracy evaluation of freely available latest high-resolution (30 m) global digital elevation models over Cameroon (Central Africa) with GPS/leveling ground control points. |
| title_full | Vertical accuracy evaluation of freely available latest high-resolution (30 m) global digital elevation models over Cameroon (Central Africa) with GPS/leveling ground control points. |
| title_fullStr | Vertical accuracy evaluation of freely available latest high-resolution (30 m) global digital elevation models over Cameroon (Central Africa) with GPS/leveling ground control points. |
| title_full_unstemmed | Vertical accuracy evaluation of freely available latest high-resolution (30 m) global digital elevation models over Cameroon (Central Africa) with GPS/leveling ground control points. |
| title_short | Vertical accuracy evaluation of freely available latest high-resolution (30 m) global digital elevation models over Cameroon (Central Africa) with GPS/leveling ground control points. |
| title_sort | vertical accuracy evaluation of freely available latest high resolution 30 m global digital elevation models over cameroon central africa with gps leveling ground control points |
| topic | dem aw3d30 srtm 1 aster gdem 2 cameroon gps/leveling orthometric heights vertical accuracy |
| url | http://dx.doi.org/10.1080/17538947.2018.1458163 |
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