How to create shifting materials in terrain

woody

How would I go about creating a terrain textures of various different substances/textures...Say I want a river running through grassland, there would be a shift in texture when it gets to the side of the river bed and underneath that.

At the moment i can only create a texture which looks tiled and cant work out how to create textures for larger environments.

This is for visualization purposes and not for games, so I guess that changes things. I'm thinking I create base terrain texture, then create more substances and lay them over the top via masks? Is there sort of a turbulence node to mask another texture over the base terrain which roughens the sides of the mask. I feel pretty limited with substance texture sizes when it comes to terrain and cant get my world machine exports into it without downsizing. 

Sorry for all the questions, with all these tools its still difficult to do simple transitions and realistic variations in materials. 

Chimp

this isn't typically handled on the substance side - you don't _usually_ want to be creating a big uber texture with transitions between surfaces etc. It is done, you might want to look into megatexturing, but more typically you create tiling textures that you blend on the mesh via vertex colours for example.

I.e the mesh or terrain has red, green, blue and alpha painted onto it and these corrispond to say, mud, grass, muddy grass, watery mud which appear where those colours were baked into the vertices. You don't see the colours, just the materials.

This is how its done most often in most fields. You get or write a shader that displays the textures where you want them and blends between them. People have come up with nice solutions for blending, one common one at the moment is height blending where you get a much nicer, more realistic blend between the two textures using their heightmaps.

see: 
this is not one texture, its a render with two materials being blended together via vert colours and utilising the heightmaps - under the hood its red on one side and blue on the other, or whatever your shader decides.

see this article:
http://www.gamasutra.com/blogs/AndreyMishkinis/20130716/196339/Advanced_Terrain_Texture_Splatting.php


merry christmas and have a happy holiday

Eric Chadwick

More here on terrain texturing.
http://wiki.polycount.com/wiki/MultiTexture

You said Visualization... are you using a game engine for this? All the major ones have built-in terrain systems using splat mapping (see the link). This can also be done in rendering apps like Max and Maya.