Procedural Or Algorithmic

A quick thought on procedural vs. algorithmic scenery: there was some discussion on the X-Plane dev list about procedural terrain; the Outerra screen shots have stirred up interest.

There is a fundamental difference between what you see with Outerra and what we do with our global scenery:

• Typically procedural scenery is based on the idea of 'amplifying data' - that is, making a little bit of data look more interesting by applying a recursive algorithm to "generate" detail.
• Algorithmic scenery involves taking a large amount of unique input data and translating it; the detail comes from not losing information in the source data.

The key difference is whether the resulting scenery comes from a process that "creates" information through a 'procedure' or "translates" information.

Our scenery process does a bit of both, but we are more in the algorithmic camp than procedural camp; the global scenery is produced from hundreds of GB of input data, and we are constantly looking for better input data to create more interesting and accurate output scenery.

In fact, I would say that we are becoming more algorithmic and less procedural. In version 9, the urban roads in non-US cities are "procedural" - an algorithm generates them from the terrain data, an algorithm, and some random noise. For version 10, we are importing OSM.

One thing I have noticed in the work on version 10 global scenery is that we've finally crossed a line. With version 9, the question was 'what is the best data we can get'. With version 9, the question is 'how much information can we keep'; we've reached a point where the resolution of our input data is so much higher than what can go on DVD, that it's a question of filtering down, not synthesizing up the resolution.