frosted silver materials

[Kinetic99]

Hello and thanks for your time.
Is there a way to make a frosted silver material so that if the silver reflects back as black, the frosted material reflects back as almost white? So it scatters the light. The more abrasive the frosted silver material, the more scattering.
The opposite would be true, so if the silver material reflects the light source back as white, then the frosted silver material would reflect back as relatively darker.

the best example I could find is this silver coin on the right side. The background is mirror silver and it reflects back as dark, but the frosted silver is whiter. the top image shows the opposite.

Also notice that there are some nice white speckles or flakes that add detail to the frosting.

Ultimately I want to create a gradient like frosting so I can use a grey scale image or something to control the amount of "frosting".

thoughts?
K

[benb32]

It doesn't look like "frosting" in the true sense of the word... the silver exhibits glossy reflections, reflecting the environment. The key light is above and slightly behind the coin display - the top row of coins are angled upwards so there is nearly a direct reflection of the light - the bottom row angled downwards, so only the surface features/detail of the embossed face reflect the light, the rest of the environment being dark. There's appears to be a lot of microfacetted detail on the embossing (not present on the surrounding flats), which gives the sparkle/roughness. Unless you're going recreate the roughness from the embossing with geo (one material for the entire coin), you'll want to have a different materials ID for the face with increased roughness.

Either way, to get close to your reference image, the lighting setup of your scene will be as important as your materials and geo.

[Art48]

It doesn't look like "frosting" in the true sense of the word... the silver exhibits glossy reflections, reflecting the environment. The key light is above and slightly behind the coin display - the top row of coins are angled upwards so there is nearly a direct reflection of the light - the bottom row angled downwards, so only the surface features/detail of the embossed face reflect the light, the rest of the environment being dark. There's appears to be a lot of microfacetted detail on the embossing (not present on the surrounding flats), which gives the sparkle/roughness. Unless you're going recreate the roughness from the embossing with geo (one material for the entire coin), you'll want to have a different materials ID for the face with increased roughness.

Either way, to get close to your reference image, the lighting setup of your scene will be as important as your materials and geo.

I'd say exactly the same. Metals are very sensitive to lighting.

[Kinetic99]

You're exactly right.
The term "frosting" was just a loose term to label it something, but what it is really is a micro-sub-surface or superficial noisy pattern that scatters any light hitting it. So up close, its like a noisy-pit-holed pattern (similar to a noise bump map), but pulled back or at normal view, its a whitish-silvery appearance with a some speckles reflecting in the light. The more noisey the sub surface roughness is, the whiter it appears in a dark-lit environment, but the darker it appears in a fully-lit environment. Here are the best examples I could find on the internet. I've tried silvery materials with noise bump maps, with the same noise bump map in the reflection glossiness slot @ 0.8. The results are good but not exact. I did not play with the roughness.
Are there better ideas on how to recreate this material so that it looks as accurate as possible at a close up view and far view?
thanks for your time. K

[Kinetic99]

Oops, here are the images

[Art48]

Have you played around with the VRayStochasticFlakesMtl?

[Kinetic99]

Have you played around with the VRayStochasticFlakesMtl?

I have but it was harder to control and my render times increased too much. I need something with more control so ultimately I can create a gradient of "frost" from black shiney silver to white "frosted" silvery material.

[Art48]

I would research exactly how this stuff is made up and how it looks under a magnifying glass and try to model/shade it EXACTLY as the real world thing. Usually VRay does a very good job of then doing EXACTLY the stuff that the real world thing does. It could also be that the material was coated in something after it was made rough and the stuff attacks the surface differently when it's roughed up than when it's polished thus varying glossiness, too etc. Try to get a sample coin or research the science behind it.

[Kinetic99]

I would research exactly how this stuff is made up and how it looks under a magnifying glass and try to model/shade it EXACTLY as the real world thing. Usually VRay does a very good job of then doing EXACTLY the stuff that the real world thing does. It could also be that the material was coated in something after it was made rough and the stuff attacks the surface differently when it's roughed up than when it's polished thus varying glossiness, too etc. Try to get a sample coin or research the science behind it.

Thanks, those are good and true points and its true, there might be something on a coin for example that make it glossier. But I have done that. - to be exactly like it is in real world. Essentially, its just a noise map with varying amounts bump intensity. That would perfectly emulate the micro pattern but it doesn't produce enough of the effect (more white scattering). I need something else I think.

Perhaps its a light energy thing: Is it possible to increase the amount of light energy in the scene with out, so perhaps there are more rays and therefore more light scattering effect, without blowing out my whites? I'm using Irradiance map and Light cache. So far I have not seen any effect on frosted silver materials.

[benb32]

Bump should get fairly close, but you might get closer by increasing the tessellation on the embossed face and using a very fine displacement (to try and model the real world properties, but do appreciate that getting it right can be difficult). If displacement is out of the question due to increased memory/render time, go with the noise map but make sure it is high contrast and apply it in part to the reflection slot. Do observe the bright rough glossy reflections are greatest on the embossed parts with the hight angle of incidence in relation to the key light and camera - you might try to mix the noise with vray dirt in an inverse way i.e. is brighter where the face meets the flat surface.

From your last post it may well be the detail of your noise maps are being lost by using the ir map as primary. Can't recommend enough that you use BF + LC. For any scene with detail, you would have to raise up the the ir map so much it will actually end up being slower than BF + LC...

[Kinetic99]

Bump should get fairly close, but you might get closer by increasing the tessellation on the embossed face and using a very fine displacement (to try and model the real world properties, but do appreciate that getting it right can be difficult). If displacement is out of the question due to increased memory/render time, go with the noise map but make sure it is high contrast and apply it in part to the reflection slot. Do observe the bright rough glossy reflections are greatest on the embossed parts with the hight angle of incidence in relation to the key light and camera - you might try to mix the noise with vray dirt in an inverse way i.e. is brighter where the face meets the flat surface.

From your last post it may well be the detail of your noise maps are being lost by using the ir map as primary. Can't recommend enough that you use BF + LC. For any scene with detail, you would have to raise up the the ir map so much it will actually end up being slower than BF + LC...

Super great ideas. thanks. will experiment some more. I have used the same bump and instanced it over to the Refl-glossiness with some good results but some of the sparkle is lost. I'll try it in the reflection slot alone but slightly more white overall so I don't loose my reflection dots where there is black.