DEMIX Difference Distribution Histograms

DEMIX seeks to rank 6 global 1 arc sec DEMs (COPDEM, FABDEM, ALOS, NASADEM, SRTM, and ASTER) [1].  It uses the difference between the global DEM and a comparable reference DEM aggregated from 1-5 m lidar-derived UTM DEMs.  For each DEM it calculates 5 criteria for describing the elevation, slope, and roughness distributions.  Evaluations for each criterion are included in the DEMIX GIS database [2].  These distributions have been used in several presentations [1,5,6].

This data set includes:

• A CSV format database table listing the 236 tiles used by DEMIX {1], summary statistics for the reference DTM version of the tile, and a link to the PNG graphic with the 3 histograms (if the tile does not have a DSM), and 6 histograms (if the tile has both DSM and DTM).  The MICRODEM GIS program [3,4] can display this database, and display the histogram for selected tiles.  Filtering of the GIS database allows display of just the histograms for tiles with selected characteristics.
• DBF version of the same database
• 236 PNG files with the difference distributions.  The histograms cover only the central part of the distributions, which should show a mode close to 0 if the DEM is unbiased.  If the histogram does not show a mode for a DEM, it's a clear indication that DEM is not very good in that tile.

References:

1. Bielski, C.; López-Vázquez, C.; Guth. P.L.; Grohmann, C.H. and the TMSG DEMIX Working Group, 2023. DEMIX Wine Contest Method Ranks ALOS AW3D30, COPDEM, and FABDEM as Top 1” Global DEMs: https://arxiv.org/pdf/2302.08425.pdf.  A revised version of this preprint will be posted soon.
2. Guth, P. L., 2023. DEMIX GIS Database Version 2 (2.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.8062008 .
3. Guth, P.L., 2023, git_microdem: https://github.com/prof-pguth/git_microdem , open source software.
4. Guth, P.L., 2023, MICRODEM: Open-source GIS with a focus on Geomorphometry:  https://microdem.org/ , download for Windows-64 installation program and CHM help file.
5. Guth, P.L., Grohmann, C.H., & Trevisani, S., 2023,  Geomorphometric and Geospatial Patterns in Differences Between ALOS and COPDEM: Geomorphometry2023. https://doi.org/10.5281/zenodo.8057703
6. Coming soon