Interview: Microsoft Flight SImulator 2000 Team: Terrain.
The newly-designed scenery for FS2000 has changed so dramatically that you might not recognize the world you've flown so many times before. It seems as though both the visible and behind-the-scenes treatment of the FS World has experienced some major changes. Whether daytime or night, summer or winter, the appearance and behaviour of the scenery are all new.
Andy: We have taken the whole terrain model that was there and threw it away! The whole scenery engine, soup to nuts, from getting the stuff off the disk to pushing the pixels onto the screen. There is not a stitch of old code left in there.
Scot: Actually Dan, the software renderer was done by a guy whose name may ring a bell with you since you come from the game community – Michael Abrash 'Father of the Polygon'. He’s just down the hall here! He built our software renderer from the ground up. Its a wonderful piece of work.
Andy: So, there was not much point in rewriting the whole thing unless it did something new and interesting and of course the big headline is the new terrain. The whole world is covered to1 kilometer or higher resolution with digital elevation match. That gives you the shape, then you’ve got to texture it with something so the same resolution as a world-wide land class map. In other words: what is the that piece of earth used for? There is an extensive list of different classifications that we get from various sources, governmental and otherwise, so that covers the whole world.
The dynamic scenery system in Flight Sim 2000 is basically the same as what was there in FS98. To add objects to the scenery information is explained in the scenery SDK that is out there.
Scot: We are not shipping a tool for doing Dynamic Scenery however.
Bruce: The SDK we provide basically as information: its not tools – we publish, for example with the scenery, we publish a lot of detail about the file formats but you have to be this tall [hands held up] to use that tool. You’ve got to know what you are doing. As Andy said, we did not aim it at the end user but to the developers who understand how to code.
Andy: I can tell you a little more about the terrain. There is a bunch of things that come for free with that, so its not just a static map of the world. Depending on what the capabilities of your system – for example lets say you have a square that says 'this is urban'. You don’t always see that same urban texture. We have multiple variations of 'what urban looks like', so the net result is in a large area of urban land. You don’t see repetition over and over again of the same title with exact square boundaries, so there’s variations that get used.
Then there’s something else, which we call transitions. There was an early form of this technology in Combat Flight Sim. But anyway, when you make a switch (let's say) from urban to farmland, if those two titles butt right up against each other you see the lines in older version. We build textures in memory on the fly to make a smooth transition from one to the other. So you never see a hard line between the two different types of terrain.
When you combine all this information, we can scale this depending on the memory your machine has, how much memory your graphics card has, so at the highest end you see something that looks like what we show on the screen shots that blows you away. At the lower end you still get the performance and all the benefits of that new terrain engine but we scale it appropriately to the capabilities of your machine so we're not bogging you down with 64 megs of textures on a 16 meg machine.
Scot: This is also scaleable upward, we are actually capable at this point of delivering a level of graphics fidelity that will literally choke the highest end machine that is available right now. But when those machines are available Flight Sim will look that much better. So the knob goes both ways!
Andy: You get a bunch of other things for free. For instance the seasons change. Some people used to complain that if you change the settings in Flight Sim, say to winter, then nothing looked any different. All the textures will change appropriately now. Winter actually looks like winter, the farmland isn’t green in the winter and you do see some snow on the ground.
Day and night, there are some great effects. First off, because the terrain is not flat you will see all the proper