Adding snow to textures

Will Faucher

Hey,
Yes I've done searches regarding this, but non catered specifically to my question, and I didn't feel like necroposting.
Now, I am trying to make snow rest upon the top of some rocks I've made. Big rocks, a rock face of a canyon actually. This is what I come up with.

It just looks SO fake. I'm assuming it is because of the shape my rocks, am I right? Would perhaps making them less angular help?

crazyfingers

Best thing you can do is get some blues in there, especially in the diffuse. The spec should be far more white and you want to have some "pop", get a seperate texture going with an alpha that only allows small dots to show through, this'll be your sparkly layer, make sure the spec power is lower for these this and pump the spec on the small sparkly dots as well and you'll get a nice snow effect, may even want some hints of snowflake in it.

Getting that together should go a long way, your skybox isn't blue so you may have to scale back the blues or get a nice blue skybox in there so the scene fits together a bit. Your scene overall is jsut a flat grey, and snow is affected a lot by light in subtle ways you may want to explore in your material.

Also throw on my polygons, too many harsh angles. Snow is soft. As for the base of your rocks, put some special snow meshes in there and use a "depth bias alpha" in the translucency, play with the values associated with that untill you get a nice fade against the rocks. It'll allow some of your snow to fade in, it's a nice effect.

Did you paint the snow into the tops or did you use a special shader to do that? I'd be interested to know how you set that up if you did!

Will Faucher

Thanks, I'm not worried about the diffuse at all right now, just the general shape the snow has. I find it too blocky so perhaps you are right, the edges are too sharp. I'll look into what you said about the snow meshes as well.
As for how I make the snow, I used a shader. No painting was done. I played around with the falloff parameters for the snow material, and when setup right, it nicely catches the edge of your model. Set the falloff type as TOwards/Away and the Direction to "World Z-Axis".

rasmus

Using the green channel of your normalmap as a mask for painted-in snow in the diffuse might also be a good idea. "DepthBiasAlpha" is an Unreal shader thingie, you won't find it in Max - might be a good idea to state software etc for clarity:P

Mark Dygert

There are ways to do DepthBiasAlpha in max its just not called DepthBiasAlpha. Anyway...

It would be good to know what software and the goal of the project, is this for rendering, a realtime engine or maybe just a realtime viewport grab? Since there are half a dozen ways to get the same things done in all the different apps but all are slightly different.

Aside from including your normal map in the falloff blend calculations, you can also draw in snow into your diffuse and normal maps. Keep in mind that snow gets blown around and sticks to things so you might want to factor in common wind direction when doing this.

It could be good to model in the snow accumulation on top of your rocks. It's often not good enough to just model rocks and turn the tops into snow unless its a light dusting.

I also think your blend line is very straight and you should jag it quite a bit to help give it an uneven look. Again half a dozen ways to do this given whatever app and the purpose of the scene.

You can also use vertex paint/color to blend snow and rocks.

If you're using 3dsmax you can also look into plug-ins like SnowFlow which you might be able to optimize down to a workable game mesh, never really tried only used it for rendering.

If you're using 3dsmax this quick tutorial covers how to add noise to the falloff blend line http://www.conceptgirl.com/tutorials/Snow3dStudioMax.pdf This same method can be used in ShaderFX and Unreal but there are a few other ways to do the same thing, it all depends on the scene and whats its for.

Will Faucher

Thanks for the help guys, I'm sorry I didn't specify the software. This will be done in Max, for a rener. Not realtime. I'll look into the methods you mentioned, they seem interesting. Otherwise, what other methods can be used for renders in max? Also, that last method you listed, that's exactly what I did in my frist attempt (screenshot in first post).

Edit: unfortunately, I do not have the means to buy an actual plugin license. This will have to be done freely. This project is for my end of year school project and I need it to be kickass, but I just don't have the money. I have the time though!

Eric Chadwick

The rocks look very low-res for a render. I would look into sculpting and/or displacement mapping. Check out the recent thread on modeling rocks.

Lighting is going to play a huge part in this. You could look into HDR env lighting with mental ray.

Also I would want to see some snow drifts at the bottoms of the rock walls, not just snow accumulation on the tops.

Are you using reference photos?

Will Faucher

Yeah they are still in blockout phase. And I'm having alot of trouble with snow. Enough trouble that I am considering just making a spring scene instead.
As for the snowdrifts, I was mainly focusing on the rocks. Despite the techniques in the new rock modelling thread, I'm having a hard time with those as well. I need more practice, alot more.

Eric Chadwick

Don't be shy about working from reference photos of real places. This is essential. I get the feeling you're just trying to wing it, trying to create a real place without constantly referring to photos. Get some photos of a real place, and emulate what you see there.