Conclusion
Realistic topography generation is an important part of the film, computer game, virtual reality and other industries. There are a number of approaches to constructing topography, from procedural methods to the use of map data.
Historically, DTM and other forms of map data have been very expensive to acquire. However, as the number of companies providing the data and the applications using it increase, so prices start to reduce.
Andrew Chapman who is a technical director at the London post-production house Framestore CFC, provided the following insight into the use of map data in the visual effects industry:
"If the terrain is simple/distant enough that we don't need to exactly model it, we just use fisheye stills collaged together on the inside of a sphere to represent the world, and just roughly model in the terrain by eye. You can actually get a pretty good approximation out of the camera tracking software too actually."
"However, if it needs to be more precise, we use map data which is cleaned up and delivered to us as a mesh. This is a pretty expensive option, but the cost is usually covered by the production."