enviroment texture question.

Rockley Bonner

I understand that an environment is a giant plane populated with separate meshes that are efficiently assigned texture maps what I don't understand is how the texture is assigned on the plane that the gamer walks through (the ground). it could be done by effectively assigning, for example, one tiling 1024x1024 texture, but I don't really see that used too much in modern large open world gaming, are the textures in the environment somthing way bigger like say 4096x4096.

how big would be too much? how are these large maps on the ground transitioned smoothly, say for example, from the desert to a town with grass? am I making sense?

ZacD

A lot of it done through vertex blending (mixing tiling textures) with texture decals to help break it up.

Rockley Bonner

http://wiki.polycount.com/Multitexture

is this an example of what your talking about, in the end how large would these textures end up being, are these textures combined or are they baked together?

ZacD

That wiki page is a good starting place. For consoles I'd expect up to 4 different 512x512 textures for most terrains, RAGE did bake down these blended terrain textures into a "megatexture" but that isn't the norm for most game engines. The UDK wiki has more specific examples and how they are used.
http://udn.epicgames.com/Three/TerrainAdvancedTextures.html

Ark

Snefer has a good free video up on Eat3D that provides a good overview of vertex blending. Although not strictly limited to terrains, it does give the idea of what is being achieved.

http://eat3d.com/free/vertex_painting

Rockley Bonner

Thanks guys, im not doing much at work today, so ill reaserch these pages.