How is the accuracy of digital elevation models typically assessed?

The accuracy of digital elevation models (DEMs) is most effectively assessed through on-site surveys and measurements. This approach involves physically collecting elevation data at specific locations using precise surveying instruments. Such direct measurements serve as a reference point to evaluate the accuracy of the DEM by comparing the surveyed elevation values to those derived from the digital model. This method provides a reliable means of determining how closely the DEM represents the actual terrain, allowing for the identification of errors and improvements in the model's accuracy.

Other methods, while useful in their context, do not provide the same level of precision needed for a thorough assessment of DEM accuracy. For example, comparing against existing digital maps can be useful, but those maps may also have inherent inaccuracies. Similarly, analyzing dimensional conformity relates more to the geometric shape rather than elevation accuracy. User feedback and evaluations can provide insights but are often subjective and not grounded in empirical measurements. On-site surveys remain the gold standard for validating the precision of a DEM.