What is a Right Resolution of DEMs?

April 27, 2020

So… How to determine an appropriate resolution for the digital elevation model (DEM)?

We need a grid resolution that optimally reflects the complexity of a terrain; one that can represent the majority of the geomorphic features. Suitable cell size can be derived for a given set of sampled elevations (e.g., contours or points), to fit the complexity of the terrain and/or the scale of work for the targeted application (Hengl and Evans, 2009).

These are some points to be considered after reviewing literature:

1. The original source.
   • When modeling elevation from vector contours, one needs to consider the horizontal and vertical intervals or the total length of the contours
   • DEM products gained from satellites (e.g., ASTER and SRTM) have fixed resolutions, increasing resolution from available datasets does not generate more information
   • LiDAR can give both fine resolutions and degraded resolutions, and both bare-earth elevation and surface elevation
2. The vertical resolution.
   • If the cell size is too fine in relation to the vertical accuracy, it might introduce local artifacts and slow down the computation of land-surface parameters.
3. The application domain.
   • Hydrological modeling
   • Solar radiation modeling
   • Topographic derivatives
   • Specific features like ridgeline, valley lines, and drainage paths
4. The terrain complexity of the interested area or the process to be modeled
   • Steep terrain (e.g., alpine region) or flat terrain (e.g., prairie)
   • Scale of the processes being modeled
   • Numerical simulation approach
   • Size of the land surface features that are to be resolved
5. Users’ demand.
   • Requirement of level of detail
   • Data volume
   • Cost