This is a collection of tools to evaluate inter-pixel consistency metrics on gridded digital elevation models (DEMs) as outlined in:
Purinton, B. and Bookhagen, B, Beyond vertical point accuracy: Assessing inter-pixel consistency in 30 m global DEMs for the arid Central Andes, 2021, Frontiers in Earth Science, https://www.frontiersin.org/articles/10.3389/feart.2021.758606.
All utility functions are found in DemErrorFunctions.py.
A script to calculate and plot three error metrics described in the paper is error_metrics.py. These metrics are:
- Gaussian smoothing and differencing, dR (m)
- Plane fit residuals, RMSE (m)
- High-pass hillshade filtering, HPHS (-)
A script to tile and run the Fourier frequency analysis on the open access SRTM-NASADEM is fourier_analysis.py.
The SRTM-NASADEM is provided in the data directory. It is a 1 by 1 degree tile at native 1 arcsec resolution in WGS84/EGM96 horizontal/vertical datum. The original data downloaded from https://lpdaac.usgs.gov/products/nasadem_hgtv001 was renamed and converted to GeoTiff format with this gdal command:
gdal_translate -of "GTiff" s25w068.hgt nasadem_s25w068.tif
In the data folder there is also a cubic spline resampled version (UTM Zone 19S, 30 m pixels) that was generated using the gdal command:
gdalwarp -tr 30 30 -tap -r cubicspline -t_srs EPSG:32719 nasadem_s25w068.tif nasadem_s25w068_utm19s_30m_cubicspline.tif