The ground elevation is used by ArcGIS Pro to represent the surface of the earth within the 3D Scene you are creating. Each Scene should have a ground surface specified. By default, ArcGIS Pro uses the Esri World Elevation surface, which is published through ArcGIS Online. Don't worry though, as using this surface from ArcGIS Online does not use any of your ArcGIS Online credits. This surface, as with the ArcGIS Online Basemaps surface, is completely free to use.
You are not required to only use the Esri World Elevation surface—you can choose to use your own elevation surface if desired. Your own local surface is often much more accurate, so it will provide better results.
The extents of a Scene are limited to the extents for the data sources used as ground elevations. This means that your Scene extents will be clipped to the total combined area covered by your ground elevation sources. To ensure your Scene displays the...