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3 - Explore the Newport DEM

Explore the Newport DEM

We now have a finished coastal DEM for Newport, Oregon.

The key question in this module is:

What source data support different areas of the DEM?

We will answer that by viewing the hillshade together with the spatial metadata in a desktop GIS such as QGIS or ArcGIS Pro.

1. Get the Newport files into your GIS

First, confirm that the files are available:

ls -lh \
  ~/workshop/newport_dem/newport_n44x64_w124x10_hs.tif \
  ~/workshop/newport_dem/newport_n44x64_w124x10_sm.gpkg

If you are using QGIS, also use the prepared style file:

newport_n44x64_w124x10_sm.qml

Download the files from JupyterLab

In the JupyterLab file browser:

  1. Open workshop folder on the left side, then newport_dem.

  2. Right-click each file.

  3. Select Download.

Download:

newport_n44x64_w124x10_hs.tif
newport_n44x64_w124x10_sm.gpkg

For QGIS, also download:

newport_n44x64_w124x10_sm.qml

Keep the .gpkg and .qml files together.

If your Newport build did not finish

If the Newport build is still running, first stop it with Ctrl+C.

Known-good Newport files are available in:

~/workshop/reference_outputs/newport/

Copy them into the Newport output directory:

mkdir -p ~/workshop/newport_dem
cp -a ~/workshop/reference_outputs/newport/. ~/workshop/newport_dem/

Then download the files from JupyterLab.

2. Look at the finished surface

Open the Newport hillshade in your GIS:

newport_n44x64_w124x10_hs.tif
Hillshade of the finished Newport, Oregon coastal DEM around Yaquina Bay.

Newport coastal DEM hillshade. The hillshade reveals the shape and texture of the finished elevation surface around Yaquina Bay.

Look for:

3. Add the spatial metadata

The hillshade shows the finished surface.

The spatial metadata shows the source-data support behind that surface.

Add:

newport_n44x64_w124x10_sm.gpkg

to your GIS and display it on top of the Newport hillshade.

Newport, Oregon hillshade with spatial metadata overlaid, showing the source elevation datasets contributing to different areas of the DEM.

Newport hillshade with spatial metadata. The overlay connects places in the finished DEM with the source elevation data used to build it.

4. Trace one location back to its source

Return to the location you selected.

Using the hillshade and spatial metadata together, ask:

  1. Which source dataset supports this location?

  2. Is direct source-data coverage dense, sparse, or absent nearby?

  3. Where might interpolation therefore play a larger role?

Inspect the spatial-metadata attributes

The GeoPackage includes attributes that provide additional information about the mapped source-data features, including the source module and relative weight or priority.

Newport hillshade with the spatial-metadata attribute table open, showing source-data information associated with mapped areas of the DEM.

Spatial-metadata attributes. The attribute table provides additional information about the source data supporting each mapped area.

The takeaway

Hillshade:
What does the finished surface look like?

Spatial metadata:
What source data support that surface?

A DEM is more useful when we can understand both the surface and the measurements behind it.

Next: apply the workflow somewhere new

Next:

Module 4 — Same Recipe, New Region

We will move to Sarasota, Florida, change the local pieces of the Newport recipe, and launch a second DEM build.

Workshop
2b - Inside the Workflow
Workshop
4 - Same Recipe, New Region