DEM of Difference vs. Differences of DEM

If you google DoD

you will likely land first on the US Department of Defense. That is not the DoD we are discussing here. Here, DoD is about DEMs and terrain change, not defense policy.

Start with the equation we agree on

DoD = DEM₂ - DEM₁

Why “elevation of difference” does not exist

Elevation is not just a number; it is a number relative to a reference surface (datum, geoid, ellipsoid, benchmark, etc.). Without a reference, elevation is undefined. So “elevation of difference” is a category error: a difference field is not itself an elevation quantity.

Why “DEM of Difference” is awkward

If DEM means Digital Elevation Model, then “DEM of Difference” reads like a model of “elevation of difference.” But DoD represents a difference between two elevations, not a new elevation. Semantically, the phrase is inconsistent.

Names that make sense

• Difference of elevation models
• Differences of DEMs (for multiple pairwise comparisons)
• Elevation difference model
• Digital elevation difference model
• DEM difference map (plain-language option)

About the “D” in DEM

When was the last time we built a non-digital elevation model for this workflow? Exactly. In many contexts, “elevation model” is already sufficient; the digital nature is implied.

Conclusion

If the goal is precise terminology, DEM of Difference should be retired. Use difference of elevation models (or an explicit alternative) and define the equation once in the methods section.