DSM and DTM are not interchangeable
A digital surface model represents the reconstructed surface, which may include roofs and vegetation. A digital terrain model is intended to represent terrain and must be evaluated separately where ground observations are limited. The file inventory distinguishes the two categories rather than treating elevation as one uniform product.
Results on this page require an orthomosaic and at least one of those elevation categories. They do not guarantee both a DSM and a DTM. Source images, camera data and point clouds may also be available, but must be checked in the scene inventory.
Verify that the rasters can be used together
Inspect coordinate reference systems, horizontal and vertical units, pixel size, grid origins, extents and nodata values. An orthomosaic and elevation grid from one capture can still require alignment or resampling before a pixelwise comparison.
Retain the transformation history when you reproject or resample a product. Geospatial alignment notes are relevant context, but an alignment estimate alone is not an independent vertical accuracy survey. Match the evidence to the accuracy your application requires.
Read elevation in its environmental context
Inspect the imagery for vegetation, water, reflective roofs, occlusions and surface changes. Photogrammetry reflects what the cameras could observe and reconstruct. A smooth grid does not establish that the underlying terrain was visible or correctly recovered.
For change analysis, require comparable captures of the same place with known dates and compatible reference systems. Different publication dates or separate scenes in a collection do not by themselves establish a usable time series.
State the analytical and licensing requirements
Specify whether the task needs surface height, bare-earth terrain, relative shape or independently validated elevations. Include target grid resolution, coordinate system, required coverage, missing-data tolerance and any auxiliary observations.
Use an available sample to inspect format and representative coverage, then confirm the full files and versions in the commercial agreement. Public metadata and map previews do not establish unrestricted use, redistribution rights or suitability for engineering decisions.