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New to Arnold - Materials help (Flake and Brush)

12 REPLIES 12
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Message 1 of 13
Willie_Frazier
443 Views, 12 Replies

New to Arnold - Materials help (Flake and Brush)

Hey guys,


I am new to Arnold, though I have been using C4D for 17 years. I picked Arnold up as I have been tasked with making some 'photorealistic' product renders and it seemed that this engine would be a solid way to get there.

However I am really hitting a wall trying to sort our the 2 main materials this object uses. The image I have attached shows both of these in a high res photo of the product in question.

First, we have this kind of 'sparkly' black plastic. From a distance you hardly notice it, but close up, it's quite clearly there as you can see. It has the characteristic of falling off into the darkness, like a fresnel sort of effect. I thought I could get there with the included metal flake car paint material, and I get kind of close, but not close enough. The first problem I have is that I simply cannot get the flakes small enough. Even at .0000001 the flakes seem to big. Oddly they seem to get even bigger when viewed from a distance. The second problem is, rather than disappearing into darker areas, they stay 'bright' making them stand out more... it's like I have the wrong 'blending mode'.

The second material is the brushed or 'scratched' sort of silver plastic. I tried scaled noises but again, couldn't get a small or 'fine' enough result, nor make those scratches catch the light like they do in the photo.

I really hope someone here can shed some light on this. I am feeling frustrated after banging on this for 7 hours and getting nowhere.

Thanks in advance!8407-tex-target.jpg

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12 REPLIES 12
Message 2 of 13

About the scaling issue, does changing the Export Scale in the render settings (e.g. to 1 cm) help?

Message 3 of 13

I did see that mentioned in another thread earlier and I did try changing those settings, but it did not seem to have an effect.

Message 4 of 13
lee_griggs
in reply to: Willie_Frazier

This looks ideal for our flakes shader. Can you upload a simplified scene so that I can have a play with it?

Have you tried scratch maps such as these? It might be worth experimenting with them using specular_roughness, bump and/or coat_normal.

Lee Griggs
Arnold rendering specialist
AUTODESK
Message 5 of 13

Thanks Lee,

Sorry it took me a minute to get back to you, I posted this at 2:30 AM and had just shut down for the night, when your answer came up. This is actually my second time writing the post, as my first go was erased from existence when I was given as sign in page after clicking 'post answer' (yay!)... so here I go again, ha.

Thank you in advance for having a look at my scene. I really appreciate it more than I can express. I will prepare a simplified version and upload it shortly (it's for an as yet unreleased product, so I will just slice a chunk off for you to play with). If I can get the flake size right and get it to falloff like a fresnel, I think I will be in business. It really is a matter of this being my first time using Arnold, so knowing what does what exactly is trial and error, and when I mess with a falloff slider, and see no difference confusion ensues.

I have attached a couple of images to show my current state. These images have the same settings, but the second one is from further away and you can see how the flakes somehow look larger... very odd. Apologies for the small size of the second image's small size, I had to capture an area that wouldn't give away the product.

As for the scratches, I'll have a look at that link. The main issue with scratch / roughness maps are the (rightly) random patterns in them, where as the finish on this looks like someone took a broad, stiff brush and just did a long stroke the length of the top, which is why I thought a procedural approach might be best.

8413-1.jpg


See how from farther away the flakes seem somehow bigger, when one would expect the opposite

8414-3.jpg

Message 6 of 13
Willie_Frazier
in reply to: lee_griggs

As promised, here is a chunk of geometry in a simplified scene. Let me know if it is sufficient. Thank you so much!

Flakes Sample.c4d.zip

Message 7 of 13
lee_griggs
in reply to: Willie_Frazier

How many Camera (AA) samples are you using for the far away shot? Try to increase it to see how it affects the flakes.

Yes, probably a procedural approach for the scratches would be better. Scale in a noise shader in one direction should do this.

Lee Griggs
Arnold rendering specialist
AUTODESK
Message 8 of 13

I want to say 4 Samples on my camera. I’m away from my studio right this minute. I will increase the samples and see what that does, though this is all going to be for close up renders only, so maybe a non issue, but I do want to know.

I uploaded the scene in a comment to your reply from yesterday. I see it there still. 🙂

Message 9 of 13

Same problem here, I was going for this look 8416-1603788713940.png

this image was a snapshot in my archives, the project files seems to be broken, probably because of flakes, I found a work around using voronoi noise (can't get the rainbow look anymore) , but the scaling is also broken I scaled the project, breaking all the lights (good thing there's light manager), but I get the same results. The project I'm doing is terribly simple, but this problem got me to stagnate for awhile


This is as close as I can get

8418-1603790104070.png

Message 10 of 13
lee_griggs
in reply to: Willie_Frazier

It looks like the scene scale is off. It all fits within a default cube. This is why you can't get smaller flakes.

8390-1603800658730.png


Also, the lighting is huuuge compared to the object size. This is why the flakes look flat. If I just put a small point light in the scene you can see how much better the flakes falloff. I would look at chucking out the lights and work on one small light at a time to 'bring out' the flakes and highlights of the object. Tbh, a studio HDR might get you there quicker and then use smaller lights to pick out the hightlights/flakes. Hope that helps.


8389-1603800621586.png

Lee Griggs
Arnold rendering specialist
AUTODESK
Message 11 of 13
lee_griggs
in reply to: jankarl.exe

Can you post this in another question, please?

Lee Griggs
Arnold rendering specialist
AUTODESK
Message 12 of 13

Hey Lee,

Thanks, that did help. Full disclosure, I typically make my own models, but this was a CAD model (Solidworks) provided by the client. So, it was using real-world scale. A default C4D Cube is 200cm all around, this product is only 57.4cm long so yeah it would definitely fit within said cube. I brought in a studio preset, and scaled the object to be proportionate to the objects in that scene, and that made a TON of difference. I had been so concerned with scene scales in the project and render settings, that I didn't even consider just scaling the entire geo up. It goes to show how one can get tunnel vision when trying to suss something out - so your fresh set of eyes was a godsend, and I thank you for them. The light that was there was I think meant to be large, it's like 4 lights in a square placed inside an all encompassing soft box, and it wasn't right for what I needed, but then a point light wouldn't quite do it. I am getting my light setup dialed in pretty well with some smaller quad lights, some of which are encased in soft boxes to make them a little more diffuse.

Once I had that sorted out, other settings that weren't providing any appreciable results suddenly started working. Changing the brightness of the white values in the three settings of the flake capped it off, and I am getting results I am very happy with right now.

At this point, I now need to sort out that brushed texture, and if it's ok, I'd like to keep this thread open just in case I hit any obstacles with that.

I can post some updated screen shots later, and will definitely link you to the final render when it goes live.

Once I finish this, hopefully I'll have a little time to watch the course I purchased from MographPlus (its the only one I could find that wasn't 3-4 years old, but it seems pretty thorough), so I can learn how to actually properly use this engine.


Thanks again!

Message 13 of 13
lee_griggs
in reply to: Willie_Frazier

Glad you are making progress! I also recommend checking out Arvid Schneiders Arnold videos. He uses MtoA but the shading nodes are the same as in C4DtoA. I am sure you can achieve something decent using mix or layer with noise shaders.

Lee Griggs
Arnold rendering specialist
AUTODESK

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