In Halo 3, we simulate Rayleigh and Mie Scattering by creating “virtual†pollution and air and passing “real†light through it for a realistic effect... Rayleigh Scattering relies on the principle that the distorting particles be smaller than the wavelength of the light...
At its very simplest level, your see Rayleigh scattering when you look from about 45 degrees to straight up, and you see Mie scattering when you look straight at the horizon. Naturally the further you can see unobstructed, the more pollutants will enter that distance, and the more haze is created. Unless you live in Los Angeles, in which case you can probably detect Mie scattering by looking across the street.
You can get an idea of what I’m talking about by watching the E3 trailer. Across the huge artifact that the Chief discovers in that trailer, you see the air start to haze over, as tiny distant particles change the color, quality and transparency of the air. When you turn off our simulation of Rayleigh and Mie scattering, the distant objects pop out and any sense of distance or scale is ruined. You might as well be looking at an object the size of the dish in Ascension.
The need for realistic distance drawing is vital in Halo 3, because of the sheer scale of our maps. The distant mountains in that E3 trailer are absolutely real geometry. You can detach the camera, fly out to them (which would take about fifteen minutes even with our camera’s “gas†button held down) and see that they’re even textured properly. This is a function of the nature of the Halo 3 engine, and testament to the 360’s horsepower. It means we don’t have to “cheat†as much with fancy skyboxes and obfuscation.
http://www.actiontrip.com/link.phtml?http://www.bungie.net/News/content.aspx?type=topnews&cid=12310
this will create for the game.
