Help with Black painted metal

[Torsten]

Hi Guys,

I am having  difficulties in achieving a black painted metal. I have attached a reference. The material i want to create is the black metal of the kitchen. I attached a screenshot of my test render and material settings. As you can see it is nowhere near the nice black as the reference material. The diffuse color is set to 2 (0-255), low reflection and matte glossiness. There is a small bump achieved by a noisemap.

Does somebody have tips, or a setup how i need to set the material to get it more soft black? Or is the only way to tweak the levels in postproduction? The scene is lit by an overcast hdri.

Thanks in advance

[romullus]

Set fresnel IOR back to 1,5 - 1,6. It's paint you are trying to recreate, not a metal.

[PROH]

Make your model less planar - make some subdivision in the mesh and apply a subtle noise. This will make softer diffused reflection. Neither your reference nor any other metal cabin will be as "straight" as your model :)

[maru]

I would say less reflectivity, lower fresnel, and less glossiness. The material in the photo (if it's the one you are after) is almost matte.

[Torsten]

Thanks guys for the input,

With some material tweakings you mentioned i managed to get similair dark results as in the picture. see attachment. The reference isn't that black too.

But now the thing i am missing in the material are the nice shiny highlights on the edges. This makes the material in the reference really vibrant and alive. My material, by lowering the reflectence, is too dull. I have tried in previous to overlay  a shiny coat with blend material, but this never really worked. Any ideas?

Thank in advance

PS I have Chamfered all the edges of the geometry, so that should not be the problem

[PROH]

I still think your model is to planar/straight. This means that the light/reflections won't variate the way it does in your reference.

[romullus]

Try to increase reflection to 0.5 - 0.7. It's way to low in your material. Alternatively you can plug fallof map into glossiness slot (front - 0.4, side - 0.8 - 1.0, falloff type - fresnel)

[Torsten]

I really appreciate you guys helping me out. I attached some more reference images, updated render and material settings. I raised the reflection to 0,5, and used a fallof curve to the glossiness slot (see attachement). I also subdived the mesh and added a noise to it. As you can see, the diffuse colour is very much lightened by the reflection pass. I think it is much better than the first try, but it still doesn't really resemble the reference.

[Rimas]

You won't get any highlights on edges if they're perfect 90 degree ones in your model. Add a chamfer to all corners or use a rounded corners feature in the material.
Remember - NOTHING in this physical world is perfectly sharp. You will even see a highlight on the edge of a sharp blade and that's because it is still not a perfect 90 degree angle :)

I can't clearly see whether the edges in question are rounded or not, but just putting it there.

Also make sure the lighting can affect them - if there's nothing to reflect - they won't reflect and give you that highlight.

On a side note - we photographers fake a lot of things. What you see in the photos shadow/tone/highlight-wise may be a composite of several images with different lighting to achieve a more pleasant look. Just a thought :P

[Rimas]

To elaborate - here's a picture I took a couple of months ago:



This is a composite of around 4 pictures with different lighting to achieve highlights where I wanted them. Sometimes we dodge/burn areas to achieve/enhance shadows and highlights. Be creative - not everything is possible with a single render without stacking and/or editing!

[Torsten]

Thanks Rimas for your insight and your example. Maybe it is the lighting, and is an HDRi not sufficient to achive these nice hightlights. I just figured that the reference also only have daylight, but i know i can't be sure of that. My goal is to come as close as possible to the reference, without too much postproduction. And i think my material could still do better, i am only not aware of what it could be. I attached a screenshot of my geometry. I chamfered all edges, but maybe they are to small.

[Rimas]

I think the problem with your material is that you put fresnel in the reflection glossiness value whereas I'd put it in the reflection color. From what I see the material is barely reflective at all when viewed straight on and then gets a bit more reflective as the angle increases - this is the fresnel affect. In theory the IOR value should deal with the BDRF curve anyway, so you shouldn't even need anything there for a simple real-world material.
I'll have a quick look if I can replicate the material myself :)

[Rimas]

Hey!

Had a quick play with 3Ds MAX and I think this could be pretty similar to what you want:



Obviously this is just a test scene out of boxes and cylinders and I haven't got your lighting setup, so it's best if you have a look at it yourself. Obviously you will need some sort of texture to it to simulate scuffs/bump or whatever you need on it, but the base shader should hopefully be close.
I've saved the scene as a MAX 2014 file for you, you can grab it here:
www.clikcreations.co.uk/corona/MatteBlack.max

Have a look at the materials provided (there are two, one is coated blend, one is not), test them, see if they shed some light on this. Hope it helps!

[Torsten]

Hy Rimas,

Thank you so mcuh helping me out. In attachment i have your material in my scene. I like the material. Simple and it has a nice feel to it. But i think the nice highlights are still missing.
I am also wondering if your setup is physically correct. If you use a custom fallof map in the reflection I think you need to turn off the IOR (set it to 999)? Otherwise you have two different reflection maps working at the same time?

[Rimas]

Agreed that it's definitely a fudge. But if you disable fresnel and just use the custom fall-off you'll just end up with a very reflective material (just tried it to confirm), which this doesn't seem to be.
The highlights, like I said, need to come from a strong light source and you need to play around with that. Make sure the HDR you're using is set up correctly (not clamping anywhere), choose the right one for the job.
If your reference was an actual photo - the photographer may have used a diffused flash to place those highlights in, etc. Getting highlights where you want them is not always an easy feat :)

That being said, I've updated the file for you:
http://www.clikcreations.co.uk/corona/MatteBlack2.max

It looks like this now in my scene:



Mind you - I have changed my chamfers to be a bit wider, I've made sure my smoothing groups have chamfers separate from the rest of the model (gets rid of bent-looking flat surface shading due to normals being averaged together with chamfers) and I've placed strong lights where they (I think) were needed).
I've also changed things around in the material, scrapped the fresnel map altogether.
Have a play around, let me know if it works for you :)