Terrain skirts and decoration techniques

armagon

In this amazing talk in the GDC Vault:

http://www.gdcvault.com/play/1277/HALO-WARS-The-Terrain-of

The developers used a tileable terrain to create a good sense of depth in the maps. They called that technique terrain skirts. In Battlefield:

http://www.gdcvault.com/play/1015676/Terrain-in-Battlefield-3-A

They seem to use a similar technique, but instead of using tileable terrain, they constrain the gameplay area to a smaller part of the terrain, and then they use what appears to be low-poly versions of high-quality WorldMachine terrains in the horizon.

Do you guys have a similar technique? I have been exporting a low-poly OBJ from WorldMachine, including the normal map, diffuse and specular. I use that object as a decoration in the engine, but the result doesn't look very good. Maybe i should export a heightmap, import into MudBox, manually paint the textures, retopologize and then export?

Eric Chadwick

You could export a heightmap and splatmaps from World Machine, and use those on subdivided planes, with tiling diffuse textures.

We have several methods here:
http://wiki.polycount.com/wiki/MultiTexture
http://wiki.polycount.com/wiki/Landscape

armagon

And use the terrain system in the engine, instead of a static mesh? Won't that be less efficient? I mean, it has to tesselate the heightmap and apply the materials based on the splatmap, wouldn't it be better to just have a static mesh and a baked material already?

cupsster

You would need megatexture to keep details. That's why there are splatmaps for this and not only for this.

cupsster

Ah, now I get you. For far detail some engines use thing called something like "base texture" which is actually in engine generated texture from your detail textures colors as by splatmap. So you actually rendering only close things with splatmaps and it fades at distance to that base texture. For far non walkable ones you are free to use whatever fits your project off course. Just be aware that there might be some LOD popping cause your terrain is creating geometry on the fly and that might introduce holes. It is hard to match static mesh lod to terrain lod.

Eric Chadwick

Nope, I would use a static mesh, and a layered shader. It's not that expensive, especially if you're efficient with layers, not using specular and normal maps on each layer, that kind of thing. It's distant mesh.

Displace a grid in Max, and use a custom shader in-game to blend the tiling maps, either using vertex color or a splatmap. Depends on the resolution needed.

Also nice to add a single normal map for the whole piece, with the details from WM or whatever erosion tool. Check the UDN link on the MultiTexture page I posted.

armagon

I'm using the diffuse from WM, as well the normal. Instead of displacing a mesh in Max or Blender, i'm using the Mesh Output device: http://www.world-machine.com/learn.php?page=devref#PRMO

cupsster

That should be all right then. Just take care with mesh density. I think WM produces quite dense meshes which might be unnecessary just for BG scenery. Duno if you can still decimate it afterwards without messing up with normal map. Maybe not, worth trying it cause I'll be using WM terrains for "skirts" as well in current project. Report back your finding.

armagon

Yeah, the diffuse WM generates doesn't look that good inside the engine. I'll try to use a different colorization macro or replace with real textures.

cupsster

I started my exploration of WM with macros but soon realized I want more control and specific features.. Hint, you can right click macro and select "Enter macro" if allowed it will show you content of it so you can learn how it is made.

This is my current graph. I added some stuff which is not there and rearranged some elements since then.


And here is output it produces



I plan to add masks for when I figure out where I'll place man made structures and some roads to keep terrain in that areas "under control".