A new assessment by NASA’s Commercial Satellite Data Acquisition (CSDA) programme has concluded that the Polar Geospatial Center’s (PGC) EarthDEM products are suitable for many Earth‑science applications — provided users account for limitations in vertical accuracy and some data artefacts.
Key findings and what they mean
Issued on 8 August 2026, the CSDA EarthDEM Quality Assessment compared two PGC digital surface model (DSM) products — the Strip DSM and the Mosaic Tile DSM — against airborne lidar samples taken across the United States and Senegal. The evaluation was carried out by NASA subject matter experts in digital elevation models (DEMs).
The report found the horizontal accuracy of the EarthDEM products met or exceeded PGC specifications and was graded “Excellent”:
- Strip DSM: 0.5 m Root Mean Square Error Horizontal (RMSEH)
- Mosaic Tile: 0.3 m RMSEH
In contrast, the vertical accuracy showed larger errors and greater dependence on surface conditions and metadata fields. Vertical performance was graded “Basic”:
- Strip DSM vertical RMSEV: 5.6 m (range by surface/cloud metadata: 4.6–6.8 m)
- Mosaic Tile vertical RMSEV: 4.9 m
| Product | RMSEH | RMSEV | Grade |
|---|---|---|---|
| Strip DSM | 0.5 m | 5.6 m (4.6–6.8 m) | Excellent (H), Basic (V) |
| Mosaic Tile | 0.3 m | 4.9 m | Excellent (H), Basic (V) |
Practical implications for users
The assessment supports the use of EarthDEM data in NASA Earth‑science work and related applications where the available horizontal precision is valuable. At the same time, it cautions that the vertical errors — sometimes several metres — and issues such as cloud‑masking weaknesses, missing surface features and occasional data voids mean the dataset is not ideal for applications requiring sub‑metre vertical accuracy.
Put simply: if a project needs very accurate ground elevation (for example, centimetre‑level change detection, detailed flood‑modelling in flat terrain, or construction surveying), users should either combine EarthDEM with higher‑accuracy lidar where available, or apply workflows that explicitly account for vertical uncertainty. For many regional and continental‑scale studies — for instance, broad terrain mapping, glacier and ice‑sheet analyses at larger scales, or initial hydrological modelling — the data are likely fit for purpose once their limitations are understood.
The report therefore makes two practical recommendations for prospective users:
- Check whether the reported vertical and horizontal accuracy meet your scientific or operational thresholds before adopting EarthDEM products.
- Examine metadata fields (such as cloud cover flags) and apply preprocessing steps to mitigate known artefacts or gaps.
Context and next steps
Quality assessment of commercial satellite elevation products is part of a broader trend in Earth observation: agencies and researchers increasingly pair satellite‑derived datasets with airborne lidar, ground surveys and other references to characterise strengths and weaknesses. This CSDA report provides an explicit, side‑by‑side evaluation that will help programme managers and the user community make informed choices.
For South African researchers and government agencies that rely on elevation data for environmental monitoring, infrastructure planning and disaster risk work, the report is a useful decision tool. It flags where EarthDEM can add value and where additional, higher‑precision data sources will be needed.
The assessment also included a documentation review of PGC resources and cited peer‑reviewed literature to place the measured errors in context. Overall, NASA concluded EarthDEM is a valuable commercial DEM resource, but one whose data characteristics must be matched to the specific science question or operational requirement.
Users are advised to consult the full CSDA EarthDEM Quality Assessment Report for detailed sample locations, methodological notes and guidance on how the results were derived.
