3 - Run the Fiji Test DEM - CUDEM/GEBCO Workshop 2026

Once the cudem environment is active and the core tools are available, we will run a small Fiji/Suva-area test DEM.

This test region gives everyone a concrete output early in the workshop. We will use the same output later to inspect DEM files, review source-data behavior, and deconstruct the YAML workflow.

Fiji Test Region¶

The Fiji test region is:

178.25/178.65/-18.30/-17.95

The bounding-box format is:

WEST/EAST/SOUTH/NORTH

For this example:

west longitude   178.25
east longitude   178.65
south latitude   -18.30
north latitude   -17.95

Run the Test DEM¶

Make sure the cudem environment is active:

conda activate cudem

Then run:

globato cudem build -R 178.25/178.65/-18.30/-17.95 -E 3s -O fiji_test -P epsg:4326+3855 -M ms_binary_cudem:algos=interp_gmt -X 0:5 global-bathy-topo

This command builds a small Fiji coastal DEM using the global-bathy-topo source bundle.

Command Breakdown¶

Command option	Purpose
`globato cudem build`	Build and run a DEM workflow
`-R 178.25/178.65/-18.30/-17.95`	Set the Fiji test region
`-E 3s`	Set the output resolution to 3 arc-seconds
`-O fiji_test`	Set the output basename
`-P epsg:4326+3855`	Set the target horizontal and vertical reference
`-M ms_binary_cudem:algos=interp_gmt`	Set the DEM compilation and interpolation method
`-X 0:5`	Extend the processing region before gridding
`global-bathy-topo`	Use the global bathymetry-topography source bundle

The -X 0:5 option extends the processing region by 5 percent before gridding. This adds a small buffer around the requested output area and can help reduce edge effects near the final raster boundary.

Expected Output¶

Expected output DEM:

fiji_test_final.tif

Additional intermediate products may also be created, including:

source masks
provenance rasters
stack files
logs
temporary processing outputs

Runtime Note¶

DEM outputs may vary slightly across systems because of differences in package versions and interpolation libraries.

For this workshop, the goal is to understand the workflow structure and confirm that each participant can run or inspect the Fiji example. Reference outputs will be available if a local run fails or produces a different-looking result.

Check the Fiji Test DEM Outputs¶

After the Fiji test DEM finishes, we will confirm that the workflow completed and inspect the main outputs.

The goals of this section are to:

Confirm that the DEM was generated
Identify missing or failed outputs
Troubleshoot data-access or credential issues
Check basic raster metadata
Perform a quick visual review before opening the YAML recipe