Creating 3D feature data
There are several ways to create 3D feature data in ArcGIS. You can create a z-aware feature class and use the interactive 3D editing tools to create new features. You can import a set of existing 3D models from other formats into multipatch feature classes. You can also convert 2D feature data into 3D feature data using a functional surface, feature attributes, or a constant value.
It is often useful to have features with 3D geometry. Although you can display 2D features by draping them over a surface, 3D features are displayed more rapidly, and they can be shared with others without having to send along the surface data. There are also many 3D analytical operations that can take advantage of 3D geometry, including complementary technologies such as Network Analyst.