impossible to get a good looking Brushed metal

[fraggle]

Hello,
I'm struggling to get a good looking brushed metal,like copper, brass, titanium with a grain 220 (as per the image attached). I tried to add a VrayBump node but the result is really not convincing at all.
I tried also to add a Vrayblend mat to a vrayscan base mat, but that's not convincing as well.
I spend on vrayscan because I was thinking that it will be a shorcut, but after weeks of tweaking, I'm wondering if it would not be looking better to start from scratch.
Any help is welcome or metal scanned material with brushed grain will be more than welcome.
Thanks

[Ivaylo Katev]

Hi, what materials you are using as starting base?

[fraggle]

I tried with several material:
Metal_matte_2_s
Metal_matte_6_s
Brass_matte_7 et 5
copper_matte_7_s
copper_matte_8_s
aluminum_gloss_brushed (but it looks like aluminum and the brushed didn't match a metal grain 220)
gold_gloss_s (by lovering the IOR and adding a bump)
http://prntscr.com/lcmu9c
http://prntscr.com/lcmv71
http://prntscr.com/lcmw13

[Ivaylo Katev]

Using bump to achieve brush like effect is not a good solution, for two reasons
- This will significantly slow down the rendering speed, because the image sampler receives non consistent results from each traced ray.
- The appearance of real brushed metal is not exactly the same as bumped flat metal, because in the bumped surface the ray may hit with equal probability a point with positive or negative inclination toward the camera, that is not the real case. In real brushed metal the distribution is highly asymmetric, i.e. you see mostly points with normals against the ray.
The grain size should be not a problem, it can be matched by simple rescale of the uv coordinates.

[fraggle]

Sure, I agreed, but using a vray blend material to add brushed reflection is not convincing too.
For the UV, as zoon as rescaled, the brushed effect just don't look anymore like a brushed metal and when increased, it looks better but fake
http://prntscr.com/lcngpv

[fraggle]

Still fitting to get a good looking brushed scan material. Adding a coat on top with a brushed reflection (fresnel on) work better but the rendering time for such a simple tree node is unrealistic and non compatible with production (20mm for 800x800 on 24 cores)
http://prntscr.com/ld7oop

[Ivaylo Katev]

i think we just have to add more brushed metals, but for now you can start with brushed aluminium and use the "paint" option to replace the color.

[fraggle]

i think we just have to add more brushed metals, but for now you can start with brushed aluminium and use the "paint" option to replace the color.

For sure that will be a better option, but when?

[MANUEL_MOUSIOL]

having the same issue right now. fraggle how did you end up creating the shader?

[kosso_olli]

Are there any news to this?
Also, the library on the Chaosgroup site is still bugged. For instance, a search for material type "metal" and tag "brushed" returns not results, although there clearly is a material called "Aluminum gloss brushed" in the metal section.

[hermit.crab]

To upload additional materials in the VRScans material library, the resources, which have to be scanned, must be provided by either clients or users (or from samples we come across) so that we can freely use, scan, and upload them. You are more than welcome to send us material samples (at your expense), which fulfill the necessary requirements and are not tied with an NDA contract, for us to scan and upload them for free. Contact vrscans@chaosgroup.com for additional information.

[MANUEL_MOUSIOL]

Wow, that's a new stance. It's nice that we can send something in. I offered that on the past but never heard back about it. Now we HAVE to send something in to get updates to a paid service. Very sad to hear.
"Samples we come across" sounds like definitely you are not pursuing your promise to update the library frequently.

[hermit.crab]

MANUEL_MOUSIOL The post was meant for the scanning of a particular material (brushed metal in this case). We are working on improving the material library by supplementing an array of additional shaders, while the upper-mentioned statement is a bonus method of doing so.

[MANUEL_MOUSIOL]

I see. Got it. Thanks for the clarification!

[kosso_olli]

You are more than welcome to send us material samples (at your expense)

What exactly is this expense? Only the cost of sending these non-tied samples to you or the cost of digitizing them at your office as well?