[Micha]

Hervé, to be totally honest, I don't really understand your problem on metals, so I post a little test. What do you think about ?

I started this post, because I think Metals in Maxwell looks to simple. Please read my first post. The default metal material seems to use only reflections. But if you look around you will see a "diffuse" glow behind the reflections in many used metals. This glow can not reproduce per plastic shader, because it follow other laws. Here should be used a other surface model as diffuse.
NL says, Maxwell will be physical correct, so I hope we get a better metals.

[Micha]

... here an example from my biased renderer AIR. I have written the shader some months befor, because I was missing the diffuse metal effect in this render engine too. Now, I hope the great simulation machine Maxwell could do it too. My example is not perfect, it is only one GI bounce used.

The first image show, like Maxwell works - pure reflections. The second image show, how a used oxidated metal should look - a combination of a special diffuse effect and reflection.
Most, the diffuse metal effect is subtle and not easy to see, so I render an image without the reflection part - image three. Good to see, I have not used the simple diffuse of a plastic.

[Micha]

... one fact from my diffuse metal shader more. As I was search for a way to get a diffuse metal, first I have tested to use the reflection blur function. But this way is very expensive, much samples are needed for a noisefree image.
Than, I start to experimenting with the diffuse function (renderman) and find, that it is much faster. So, what we need for Maxwell is not a layer material with two reflection layers, we need a illumination model for diffuse metals in combination with reflections.

[tom]

It's called Maxwell Plastics

[Micha]

Tom, I have the feeling you are married with Maxwell. You try to sell a plastic as metal. This is not serious. A diffuse calcultion can not replace a "diffuse metal" calculation. I'm not sure which illumination model should be used here, but the plastic diffuse is not the right answer. This is only a temporary solution. I say it, the standard diffuse dosn't based on the reflection law.

Tom, what you could do is, to talk with the developing team about the problem of the metal.

[Mihai]

The question is, would a highly reflective plastic, as reflective as a metal, look any different than a metal?

Personally I prefer the layered approach because of several reasons:

- true to how it is in real life, metal could have a layer of "smog" together with oxidized metal

- often we would perhaps like to mix a clear plastic coating with a metal base underneath, so having a separate "metal diffuse" would only be confusing.

- how do you know that these layers of dirt or/and oxidation have the reflective curve of metals? Perhaps this layer reflects light more like a diffuse plastic, since light actually penetrates and scatters around in it?

[tom]

Tom, I have the feeling you are married with Maxwell. You try to sell a plastic as metal. This is not serious. A diffuse calcultion can not replace a "diffuse metal" calculation. I'm not sure which illumination model should be used here, but the plastic diffuse is not the right answer. This is only a temporary solution. I say it, the standard diffuse dosn't based on the reflection law.

Tom, what you could do is, to talk with the developing team about the problem of the metal.

Micha, it seems like you stick to names too much Don't break my heart by calling me a fanboy. I'm serious about technical things. The word PLASTICS does not represent a plastic substance itself, you should use it for such situations just because it has 2 reflection components which you need. Well, I see you still think there should be a missing and/or wrong thing. I have a question to you: Do we really need to build everything with seperate shaders? What will you think if I say they are all working with the same principles? Do you know, even a metal has a transparency? What if you have one common set of settings for representing everything one day? Stay tuned...

[Micha]

The question is, would a highly reflective plastic, as reflective as a metal, look any different than a metal?

No, I know, that plastic and metal have different IOR, but this parameter is missing. If somebody use a plastic as metal, than it is not physical correct.

Personally I prefer the layered approach because of several reasons:

- true to how it is in real life, metal could have a layer of "smog" together with oxidized metal

- often we would perhaps like to mix a clear plastic coating with a metal base underneath, so having a separate "metal diffuse" would only be confusing.

I don't understand. For what did you use it? Or did you mean a metalic carpaint?
An other nice example of diffuse metals are used coins. But here you find no plastic coat. I think, we need a textured metal material with a diffuse base and metalic reflection. For example you need it for a knight's armor. Look at the image, this is not a textured plastic.

- how do you know that these layers of dirt or/and oxidation have the reflective curve of metals? Perhaps this layer reflects light more like a diffuse plastic, since light actually penetrates and scatters around in it?

In many cases the dirt and oxidation have reflective curves. It is viewable. If you have a feeling for the effect (look at my seperate rendered metal layers), than you will see it. But you are right, this effect can shift to a simple diffuse effect, for example very strong oxidated aluminium. It could be great if we could select the illumination model. I think, other matured render engines allow the user this selection.

[daros]

I agree. Maxwell metals are theoretical metals with 0 diffuse light reflection.
By using plastics you loose anisotropic reflections.

[aitraaz]

but, i mean, anisotropy is related to microstructure i thought...metals (brushed metal), plastics (cd's), cloth (fibers), wood, paper, etc...not specific to one category, eg., metals...maybe the material layering could solve that...

[Micha]

Tom, I have the feeling you are married with Maxwell. You try to sell a plastic as metal. This is not serious. A diffuse calcultion can not replace a "diffuse metal" calculation. I'm not sure which illumination model should be used here, but the plastic diffuse is not the right answer. This is only a temporary solution. I say it, the standard diffuse dosn't based on the reflection law.

Tom, what you could do is, to talk with the developing team about the problem of the metal.

Micha, it seems like you stick to names too much Don't break my heart by calling me a fanboy. I'm serious about technical things. The word PLASTICS does not represent a plastic substance itself, you should use it for such situations just because it has 2 reflection components which you need. Well, I see you still think there should be a missing and/or wrong thing. I have a question to you: Do we really need to build everything with seperate shaders? What will you think if I say they are all working with the same principles? Do you know, even a metal has a transparency? What if you have one common set of settings for representing everything one day? Stay tuned...

Tom, if you would be a perfectionist, than your heart would break by the simple Maxwell materials. I have look on so much metals as I was working on my shader, because I has try to understand, how it look. And now I see this metals here. It's like plastic metal armatures in the bath room - it's a fake.
I don't want to get seperate shaders, I hope to get a full functional metal shader with some presets. A texture is a must. I know, in the moment we can not choose the color. Maybe, I should start here.

My motivation to post here is not to say, forget Maxwell. No, I want to get more from this great engine. It's like tuning a motobike - he, the special air filter and the dynojet kit bring it. Upps, wrong subject.
If you say, all material work with the same priciples, than I belive it. But I know, they don't use the same parameter. And here we should get more control.
Also, I have posted so much examples of metals with so much live inside, that I wonder me how you can ignore this and say, this plastic rendering with a plastic coating is it. I don't speak about the textures. I think, the rendering of my biased renderer should show, what I mean - this magical glow of bright reflections. I spend so much time to explain how we could get a better metal, but I feel I waste my time here.

[Frances]

Tom, I have the feeling you are married with Maxwell. You try to sell a plastic as metal. This is not serious.

Bathsheba tweaked my ear for even suggesting it.

[Hervé]

sorry to jump in, but I have read somewhere that wood also needs a very special shader..... sure if you have super waxed wood you'll use plastics.... but it is far the case with other woods, and the way they reflect light...

[Micha]

Herve, please look here:

http://www.maxwellrender.com/forum/viewtopic.php?t=7399

At the moment I can reproduce two effects, the wrong and the right. But I have a trace. I hope I can post a result in some minutes. Seems to be a bug.

[Mihai]

I think, the rendering of my biased renderer should show, what I mean - this magical glow of bright reflections. I spend so much time to explain how we could get a better metal, but I feel I waste my time here.

Well I think it's great that you are looking at things in so much detail and try to bring up these points. What I don't agree with you is sometimes you jump too quickly to a conclusion and sometimes the conclusion is...uh...biased
What I mean by that is you immediately want a material implementation in Maxwell based on your old renderer. You say, it should work like this, because my old renderer works like this. I'm saying forget all that, forget about the blinns and the phongs, and instead take the realistic approach, first identify WHY a worn metal looks the way it does, what are the reflection curves of a plastic vs a metal, why is it different and so on. NL should then proceed to give us shaders based on those measurements, not some old implementation.

If you want a worn chrome metal for example, then have a shader which at it's base is a brand new chrome, and on top of that add a layer of dust or oxidation. This way you will get the most accurate look, more accurate than you could ever achieve with your example in your old renderer. I'm exaggerating here a bit, because honestly if you can tell real chrome from plastic chrome just by looking at it, then you have very special eyes