4 - Check Fiji DEM Outputs - CUDEM/GEBCO Workshop 2026

After running the Fiji test DEM, we will check the generated outputs. This step confirms that the environment is stable, that the test command completed successfully, and that participants can find and inspect their output files.

The main goals are to:

Confirm who successfully ran the Fiji test DEM
Identify failed runs or missing outputs
Troubleshoot installation, credential, or data-access issues
Make sure the cudem environment is stable before moving into the YAML walkthrough
Begin thinking about basic DEM quality-control questions

Expected Output Files¶

Expected output DEM:

fiji_test_final.tif

Expected output shaded relief image:

fiji_test_final_hs.tif

Check the DEM Metadata¶

Run:

gdalinfo fiji_test_final.tif

Useful things to check in the gdalinfo output include:

Driver
Size
Coordinate System
Origin
Pixel Size
Corner Coordinates
Band information
NoData Value

This confirms that the output is a valid raster and gives basic information about the DEM extent, resolution, coordinate reference system, and data values.

Create a custom color shaded-relief map:¶

Inspect the default shaded-relief image in the “fiji_test” directory. Create a custom, color shaded-relief map by adjusting the parameters to globato perspecto hillshade:

globato perspecto hillshade --help

globato perspecto hillshade --cmap etopo --exag 3 fiji_test_final.tif fiji_test_custom_hillshade.tif

This creates a georeferenced, color shaded-relief map that can be reviewed without opening an external GIS application.

Basic Visual Checks¶

This is not a full validation step. The goal is to confirm that the workflow ran and produced a reasonable output.

Things to check:

Does the DEM cover the expected Fiji test region?
Do land and water areas appear in the correct places?
Are elevations generally positive on land?
Are underwater elevations generally negative?
Are there obvious missing-data areas?
Does the output look broadly similar to the instructor example?
Are there obvious artifacts near the coastline or raster edges?

If the final DEM looks wrong, do not assume the entire workflow failed. Later sections will show how to inspect intermediate products such as source masks, provenance files, and stacked source rasters.

Troubleshooting Questions¶

If the output is missing or incomplete, check:

Was the cudem environment active?
Did the command complete or exit with an error?
Did the workflow fail while accessing a remote data source?
Did Copernicus Marine credentials work?
Was the output written to a different folder?
Did the command use the expected region and output name?

The goal of this section is to get everyone to a stable point before opening and deconstructing the YAML recipe.