In today's presentation, I pulled up an interchange system with 4 levels of interstate highway and ramps with a similar aspect to what you see below - an aerial view. The question from an attendee was (to paraphrase) "how do you get an aerial view from a system mounted on a suburban?" My response was to make an analogy to ArcGIS and various feature datasets as these were well versed GIS users. I have had this question in the past but moved about the room to represent the change in perspective.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeO64y6IAPmh31Uv3NFYu-2XDHgDB9k3Gk1u8RKxsw8K8xypzQGZh3z0BV58q2uTudoL_L4GX6NZqFul0wTV3RGj3hKdeQvyFOq3Sifn4ijAK51zyJ5I4eC6KEeUNCPn1EC5EVOzSbei4/s640/Interchange_0002.jpg)
Having spatially sound, 3D information allows for an infinite number of perspectives - includes the position of the observer, target and a field of view. This ability provides the framework for a number of applications including line of sight analysis, obstructions, glide slopes, transportation/infrastructure design and 4D modeling.