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 the scale of work for the targeted application.
(Hengl and Evans, 2009)

These are some key considerations drawn from literature:

1. The original data source
   • When modeling from vector contours, horizontal and vertical intervals or the total contour length affect the resolution choice
   • DEMs from satellites like ASTER and SRTM have fixed resolutions; artificially increasing resolution adds no new detail
   • LiDAR supports both high and degraded resolutions and provides both bare-earth and surface elevation models
2. The vertical resolution
   • If spatial resolution is too fine compared to vertical accuracy, it may introduce local noise and slow down the computation of terrain derivatives
3. The application domain
   • Hydrological modeling
   • Solar radiation analysis
   • Slope, aspect, and curvature computation
   • Identification of features like ridgelines, valleys, and drainage paths
4. The terrain complexity or the process to be modeled
   • Steep terrains (alpine zones) versus flat landscapes (prairies)
   • Scale and resolution of the process being studied
   • Size of the landform features to be captured
   • Numerical simulation method used
5. User demand and constraints
   • Desired level of detail
   • Available storage and processing power
   • Budget or licensing cost associated with higher-resolution data