Is there a trick to making large rock formations?

christopheduron

Hello again,

Currently trying to create several rock formations both small and large. My current workflow with the larger rocks has been simply hand painting them.

I'm moving on to the large rock formations now and after some tests it seems that hand painting isn't a good approach for this. A single 2k material still gives me a very blurry result since, obviously, the rock is quite big. For these larger rock formations i'll probably have to use tiling textures if i want to keep the textures nice and crisp.  

If i had to make large and flat rocks i doubt this would be a problem, but my rocks are very pointy so i don't think it's possible to keep them in a single UV island. 2 islands is possible, but obviously it leaves me with a giant seam along the object when using tiling textures.

So is there a specific trick to this? Is there a way of hiding seams by overlapping them with new geometry somehow?

Thanks for reading.

christopheduron

A quick test of a large rock formation. This one was easy since it doesn't have a backside. So uv mapping is easy. Still quite clueless on what to do when rocks need to visible from all different angles though. Perhaps merging different models together is the key?

Eric Chadwick

Most games use a set of uniquely-textured differently-sized rocks. Then just mash them together to make larger layouts. 
http://wiki.polycount.com/wiki/EnvironmentSculpting#Rock_and_Stone

If you have tight memory limits, like with mobile or non-streaming console, then tiling textures are the way to go.
http://wiki.polycount.com/wiki/EnvironmentSculpting#Tiled_Cliffs_and_Grounds

Just have to be careful to use the simplest shader possible to mix only the # of layers you need, as often your shader complexity is the main performance killer.
http://wiki.polycount.com/wiki/MultiTexture

christopheduron

Thanks for the information, i'll give them a read.

Pizdos

I will go a bit further, maybe you can get other advices if you tell us on what engine are you planing to use.

christopheduron

I'm currently trying to create some rocks in Cryengine. I've been looking at the default assets from the engine since there are some rather nice looking rocks in there and i think i'm on to something, but i don't know how to recreate it yet. Let me explain:





It's a fairly simple shape with a global smoothing group. The detail comes from the basic texture which in case of this rock (it's a giant one) is tiled 16 times so it looks good up close. The detail comes from a detail map that seems to be created specifically for this object. This is also the case for several other types of default rocks. This detail map is tiled 0.125 times. I wonder how this detail map is created. It seems like it's some sort of a highpoly bake of this object since all the detail falls into place perfectly for this asset alone. But why is it tiled with a factor of 0.125 then?

I hope someone can explain this to me .

christopheduron

There are supposed to be 3 pictures. One with the detail map of the rock disabled. It says the image is already in the discussion so i can't add it... Not sure how to fix so i'll just rename it and post it again .

Eric Chadwick

Usually what's called a "detail map" is a tiled texture which is tiled a lot across the model, so it still has detail when up close.
http://wiki.polycount.com/wiki/Detail_map

But it looks like from your example that what they call a detail map on this asset is actually a uniquely-UV'd normal map (the orange image). This looks like it was baked from a high-poly sculpt. It's also been swizzled into BlueGreenRed order, but the previewer is trying to display it in RGB order, thus the weird colors. If you un-swizzled it, it would look like a regular normal map.

christopheduron

Let's say i've made my high poly large rock. I then bake it onto a low poly and obtain a normal map. I put my low poly rock in-game, add a random tiling rock texture to it and tile it multiple times until it looks crisp up close. I then add a detail texture to give it large detail. This detail map will be the normal map i baked earlier, but then 'swizzled' .

If my UV unwrap fits my texture space, there should be no need to tile this detail texture, so my tiling would remaing default. How do they achieve it so that the tiling has to be multiplied for it to fit the model?

musashidan

This is for UE4 but shows an example the same as the one you've posted, without the swizzling.

https://m.youtube.com/watch?v=aPu7KqCZhnw

Eric Chadwick

christopheduron said:

If my UV unwrap fits my texture space, there should be no need to tile this detail texture, so my tiling would remaing default. How do they achieve it so that the tiling has to be multiplied for it to fit the model?

Looks to me like they pre-scaled the UV to be 16x. Which means the color map is automatically tiled, but the normal map must be un-tiled by using 0.125 scale. Kind of a weird workflow, but certainly valid. Just backwards from the usual way of working. I wonder what their reason was?

christopheduron

I found a guide explaining this method a bit more in depth. Apparently it's better to use his method if you're going for really large scale assets like huge boulders and trees. Otherwise it's best to stick with the normal workflow i suppose .

Eric Chadwick

Can you share the link?

christopheduron

Ofcourse

http://docs.cryengine.com/display/SDKDOC2/Unified+Detail+Mapping+in+Cryengine
http://docs.cryengine.com/display/SDKDOC2/Detail+Maps