Creating a wet look with specular/gloss maps

PHaynes888

Hi all

I'm at the stage with a project where I have a more or less textured tyre for a car and I need to create the specular and gloss maps for it. I need the tyre to appear wet as in the final scene it's going to be raining, however I'm struggling to achieve the right results. Currently it looks like this:



It seems that the specular levels are underpowered and the spec and gloss maps combined are over-riding the detail in my base texture. Also it doesn't look wet, just a bit faded.

So I'm wondering if anyone can point me in the direction of some good tutorials for this kind of thing, or offer up any advice? I'm still at the stage where I'm not quite sure how bright either map should be, or how to get that pinpoint wet area look on the model. Do I also need to be using reflection maps?

This is essentially what I'm aiming for:



Cheers for any advice!

r_fletch_r

firstly you need to use an environment map, secondly you need a high gloss fresnel type reflection. what are you rendering in?

bugo

fletch is right, you wont be able to make it that real without a cubemap.

Ace-Angel

Decent cubemap which is mostly bright, proper Normal map details for the tire rough effect, low Roughness values alongside a monstly 'mono' spec map.

PHaynes888

Ok cheers guys, I'm rendering it in Max, I'll look into cubemaps though I'm going to have to look up what a high gloss fresnal type reflection is Also it looks like I'll have to try some extra roughness/the mud into the normal map somehow

Another question, where does the environment map get applied in Max? Is it the same thing as the reflection map?

Ace-Angel

Yep, that's the one.

You can take a really noisy bump/normal map and tile it as a generic detail texture on your model with masks here and there as to break up the uniformity.

As for the Fresnel thing, I'm not sure how you would do it in Max...I guess you could choose 'Fresnel' under Specular? Although I'm not sure it applies the rest of the math correctly and all.

PHaynes888

That detail map idea sounds like the way forward, the text on the tyre is currently the only thing in my detail map, so I suppose if I add subtle noise to that too it will produce the desired effect? Does the noise have to come from a normal map or can it come from another texture?

Ace-Angel

Grayscale map inside a Bump slot will do just fine.

Computron

Helder Pinto has a Eat3d Training DVD that might interest you. He makes a tire material and all the necesary textures and shader parameters like IBL cubemaps.

PHaynes888

Ah that would help actually, I forgot all about those, Helder works in the same company as I do so I think these are hosted on our servers somewhere, I'll check them out

Computron

Lol, How many Cryteks are there?

PHaynes888

How many offices? A few around the country I work in the UK one

I'll try some of the suggestions in this thread this week when I have time and will update with progress

PHaynes888

Ok so I've abandoned the idea of making the tyre wet as I've realised/been told that CryEngine handles all that within the shader parameters. With that in mind, I've tried to create a specular map and in the alpha channel of that I've put the gloss map (as I've been told is the way to set these up for CryEngine). I've also imported the tyre into cryengine, and I have some more issues:



As you can see in the image, there is a visible seam running around the edge of the tyre. I only have one light source on the mesh, but whereever it's placed the seam is visible. Also there are some over-riding areas of glossiness that make parts of the tyre seem really contrasted (such as at the bottom of the tyre).

I'll put my specular and gloss maps below in case anyone can identify the issues. Also these are my first attempts at specular or gloss maps, so they are most likely riddled with problems as even though I'd read up on them I'm not sure I fully understand the end result. If anyone can share any tips on making them better/more suitable for a tyre then it'd be much appreciated!

SPEC:



GLOSS:

pior

Your spec looks like a diffuse and your gloss just like a spec
You need to ask yourself why are some materials different from others. For instance, the white lettering has no reason to have a brighter spec value than the tire - it is just matte paint after all. If anything, it could even be darker than the rubber, spec-wise.

In general gloss maps work best with very flat values. Adding too much detail in them (like what one would put in a diffuse and/or spec) creates a very weird look in the end. Metal start too look like dirty plastic, and so on.

That being said, that CE shot with the rain looks quite convincing

PHaynes888

Cool, thanks Pior, I swopped the gloss and the spec around for now then and darkened the text

I got rid of the weird edge seam problem too, I had read online that to enable the gloss map as the alpha of the spec map you had to enable the tick box in the shader params in CryEngine 'PerPixel spec shininess', yet that causes the seams. Probably something wrong with my gloss map then I guess?

Ark

You'll probably also want to darken the diffuse map since the surface will receive less diffuse reflectance and more from specular reflectance.

[HP]

Your normal map is inverted btw, flip the green chanell!

And your gloss is wrong, darker values means rougher surface (drier) and brighter values means more glossy reflections (wetter) so with that being said, your gloss map is wrong.