Multi-scale Terrain Attributes and Sentinel-2 Bare Soil Composites for Digital Soil Mapping in Bavaria

Band Descriptions

The 36 bands are organized into four covariate categories. The terrain attributes have been derived using SAGA-GIS (System for Automated Geoscientific Analyses) accessed through the R package Rsagacmd (https://doi.org/10.32614/CRAN.package.Rsagacmd).

1. Digital Elevation Model (Band 1)

• Band 1 - DEM: Sink-filled digital elevation model processed using SAGA-GIS ta_preprocessor fill_sinks_planchon_darboux_2001() function

2. Topographic Openness (Bands 2-11)

Topographic openness expresses the dominance (positive openness) or enclosure (negative openness) of a landscape location, derived using SAGA-GIS ta_lighting topographic_openness() function. Multiple radial limits were applied:

• Band 2 - TPO_10: Topographic openness, radius 10 m

• Band 3 - TPO_100: Topographic openness, radius 100 m

• Band 4 - TPO_1000: Topographic openness, radius 1,000 m

• Band 5 - TPO_10000: Topographic openness, radius 10,000 m

• Band 6 - TPO_215: Topographic openness, radius 215 m

• Band 7 - TPO_2154: Topographic openness, radius 2,154 m

• Band 8 - TPO_222: Topographic openness, radius 222 m

• Band 9 - TPO_46: Topographic openness, radius 46 m

• Band 10 - TPO_464: Topographic openness, radius 464 m

• Band 11 - TPO_4642: Topographic openness, radius 4,642 m

3. Slope (Band 12)

• Band 12 - SLOPE: Terrain slope derived using SAGA-GIS ta_morphometry slope_aspect_curvature() function

4. Topographic Position Index (Bands 13-22)

The Topographic Position Index (TPI) characterizes the relative topographic position by calculating the elevation difference between a focal point and the mean elevation of the surrounding neighborhood, derived using SAGA-GIS ta_morphometry topographic_position_index_tpi() function. Multiple neighborhood radii were applied:

• Band 13 - TPI_1000: TPI, radius 1,000 m

• Band 14 - TPI_114: TPI, radius 114 m

• Band 15 - TPI_147: TPI, radius 147 m

• Band 16 - TPI_20: TPI, radius 20 m

• Band 17 - TPI_271: TPI, radius 271 m

• Band 18 - TPI_31: TPI, radius 31 m

• Band 19 - TPI_419: TPI, radius 419 m

• Band 20 - TPI_48: TPI, radius 48 m

• Band 21 - TPI_647: TPI, radius 647 m

• Band 22 - TPI_74: TPI, radius 74 m

5. Sentinel-2 Bare Soil Reflectance Composites (Bands 23-36)

Multi-temporal bare soil composites derived from Sentinel-2 imagery using the Soil Composite Mapping Processor (SCMaP) methodology. Bare soil pixels were identified using the combined NDVI and NBR index (PV+IR2) that optimizes the exclusion of photosynthetically active and non-photosynthetically active vegetation. The dataset contains 14 SRC bands:

• Bands 23-29 (SRC_1 to SRC_7): Mean bare soil reflectance composites from Sentinel-2 bands

• Bands 30-36 (SRC_8 to SRC_14): Albedo-normalized bare soil reflectance composites (normalized per scene using mean reflectance across all six reflective Sentinel-2 bands)

Additional methodological details are available in https://doi.org/10.1016/j.rse.2017.11.004 and https://dx.doi.org/10.1016/j.isprsjprs.2023.06.003.