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DEM comparison

3 Methods

3.1 DEMs

DEMs have been obtained by DEW (for DEW-use only) for a large part of South Australia with resolution of roughly 10 m.

Table 3.1 lists the available DEMs.

Table 3.1: Available DEMs
DEM type reference licence file
ALOS DSM FALSE public SA_ALOS_AW3D30v4_DSM_30m.tif
Copernicus DSM FALSE public SA_Copernicus_GLO30v2022_1_DSM_30m.tif
Outback DTM TRUE DEW only AW3D_Outback_2006_2011_DSM_10m_LCC.tif
Ag DTM TRUE DEW only WorldDEMNeo_SAAgriculturalZone_2017_2021_DTM_10m_LCC.tif
SRTM DTM FALSE public Australia_SRTM_Feb2000_DEM-H_30m_WGS84.tif

3.2 Processing

For each DEM, the following processing was applied (where applicabe):

  • reprojected into GDA 2020
  • masked to the minimum available overlap between all DEMs (in each area)
  • aggregated or disaggregated to roughly 30 m from original resolution
  • reprojected into the same 30 m raster
  • generation of derived rasters via:
    • Qfit function in the MultiscaleDTM package (A. Ilich et al. 2024; A. R. Ilich et al. 2023, 2021) using v argument (window size): 3 cells.
    • terrain function in the terra package (Hijmans 2025) using default arguments (effectively using a window size of 3)
    • land_class function in theenvRaster package (Willoughby 2025) using 3 cells for the small window and 11 cells for the large window as input to the 10 class landscape classification
  • all values from the derived rasters used to generate a range of visualisations and summary statistics.

The Qfit function was used to generate the following metrics:

  • elev
  • qslope
  • qaspect
  • qeastness
  • qnorthness

The terrain function was used to generate the following metrics:

  • TPI
  • TRI
  • TRIriley
  • TRIrmsd
  • roughness

3.2.1 Scripting

The data analysis and report writing were done via a scripted workflow using the programs ‘R’ and ‘R-studio’. R (R Core Team 2025) is a free software environment for statistical computing and graphics. R can be extended via a range of packages that enable specific tasks or analyses. The packages used to produce this report are listed in Table 3.2. R-studio provides a range of user-friendly features to facilitate interaction with R.

All code is stored in a version control system at DEM.


Table 3.2: Table 3.3: R (R Core Team 2025) packages used in the production of this report
package citation loadedversion date source
base R Core Team (2025) 4.4.3 2025-02-28 local
bookdown Xie (2024a);Xie (2016) 0.41 2024-10-16 CRAN (R 4.4.2)
dplyr Wickham et al. (2023) 1.1.4 2023-11-17 CRAN (R 4.4.2)
envRaster Willoughby (2025) 0.0.0.9000 2025-05-05 Github ()
envReport Willoughby and Zylinski (2025) 0.0.0.9000 2025-05-31 Github ()
envTargets Willoughby, Allan, and Zylinski (2025) 0.0.0.9000 2025-06-30 Github ()
forcats Wickham (2023a) 1.0.0 2023-01-29 CRAN (R 4.4.2)
fs Hester, Wickham, and Csárdi (2024) 1.6.5 2024-10-30 CRAN (R 4.4.2)
geotargets Tierney, Scott, and Brown (2025) 0.2.0.9000 2025-02-21 https://njtierney.r-universe.dev (R 4.4.2)
ggplot2 Wickham et al. (2024);Wickham (2016) 3.5.1 2024-04-23 CRAN (R 4.4.2)
ggridges Wilke (2024) 0.5.6 2024-01-23 CRAN (R 4.4.2)
kableExtra Zhu (2024) 1.4.0 2024-01-24 CRAN (R 4.4.2)
knitr Xie (2024b);Xie (2015);Xie (2014) 1.49 2024-11-08 CRAN (R 4.4.2)
lubridate Spinu, Grolemund, and Wickham (2023);Grolemund and Wickham (2011) 1.9.3 2023-09-27 CRAN (R 4.4.2)
MultiscaleDTM A. Ilich et al. (2024);A. R. Ilich et al. (2023);A. R. Ilich et al. (2021) 0.8.3 2024-01-22 CRAN (R 4.4.2)
purrr Wickham and Henry (2023) 1.0.2 2023-08-10 CRAN (R 4.4.2)
readr Wickham, Hester, and Bryan (2024) 2.1.5 2024-01-10 CRAN (R 4.4.2)
rmarkdown Allaire et al. (2024);Xie, Allaire, and Grolemund (2018);Xie, Dervieux, and Riederer (2020) 2.29 2024-11-04 CRAN (R 4.4.2)
sf Pebesma (2024);Pebesma and Bivand (2023);Pebesma (2018) 1.0-19 2024-11-05 CRAN (R 4.4.2)
stringr Wickham (2023b) 1.5.1 2023-11-14 CRAN (R 4.4.2)
tarchetypes Landau (2025a);Landau (2021a) 0.13.1 2025-05-08 CRAN (R 4.4.3)
targets Landau (2025b);Landau (2021b) 1.11.3 2025-05-08 CRAN (R 4.4.3)
terra Hijmans (2025) 1.8-52 2025-05-26 https://rspatial.r-universe.dev (R 4.4.3)
tibble Müller and Wickham (2025) 3.3.0 2025-06-08 CRAN (R 4.4.3)
tidyr Wickham, Vaughan, and Girlich (2024) 1.3.1 2024-01-24 CRAN (R 4.4.2)
tmap Tennekes (2025);Tennekes (2018) 4.1 2025-05-12 CRAN (R 4.4.3)