EVALUATION OF ELEVATION, SLOPE AND STREAM NETWORK QUALITY OF SPOT DEMS
Digital elevation models are considered the most useful data for dealing with geomorphology. The quality of these models is an important issue for users. This quality concerns position and shape. Vertical accuracy is the most assessed in many studies and shape quality is often neglected. However,...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2012-07-01
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| Series: | ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences |
| Online Access: | https://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/I-2/63/2012/isprsannals-I-2-63-2012.pdf |
| Summary: | Digital elevation models are considered the most useful data for dealing with geomorphology. The quality of these models is an
important issue for users. This quality concerns position and shape. Vertical accuracy is the most assessed in many studies and shape
quality is often neglected. However, both of them have an impact on the quality of the final results for a particular application. For
instance, the elevation accuracy is required for orthorectification and the shape quality for geomorphology and hydrology. In this
study, we deal with photogrammetric DEMs and show the importance of the quality assessment of both elevation and shape. For this
purpose, we produce several SPOT HRV DEMs with the same dataset but with different template size, that is one of the production
parameters from optical images. Then, we evaluate both elevation and shape quality. The shape quality is assessed with in situ
measurements and analysis of slopes as an elementary shape and stream networks as a complex shape. We use the fractal dimension
and sinuosity to evaluate the stream network shape. The results show that the elevation accuracy as well as the slope accuracy are
affected by the template size. Indeed, an improvement of 1 m in the elevation accuracy and of 5 degrees in the slope accuracy has
been obtained while changing this parameter. The elevation RMSE ranges from 7.6 to 8.6 m, which is smaller than the pixel size (10
m). For slope, the RMSE depends on the sampling distance. With a distance of 10 m, the minimum slope RMSE is 11.4 degrees. The
stream networks extracted from these DEMs present a higher fractal dimension than the reference river. Moreover, the fractal
dimension of the extracted networks has a negligible change according to the template size. Finally, the sinuosity of the stream
networks is slightly affected by the change of the template size. |
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| ISSN: | 2194-9042 2194-9050 |