Digital Elevation Models are often created from photogrammetry, but can also be produced through land surveying techniques. While this used to be a highly specialized domain requiring costly equipment and highly trained personnel to produce high-quality mapping data, there are now data elevation data sets available that can get you up to speed for your mapping workflows. It has also become easier to combine other data sources such as aerial and satellite imagery or collect your own data using drones. However, for accurate, reliable and surveying-grade results, a geospatial data service provider will be the best choice for creating digital elevation models and derivatives.