Author Topic: Is this possible with corona? (proper brushed metal)  (Read 9757 times)

2018-12-05, 22:11:43
Reply #15

Jpjapers

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I let that link here, really interesting and informative : https://renderman.pixar.com/stories/cars-3

Incredibly interesting! Worth it for the Close up pixar renders haha.

2018-12-05, 23:00:33
Reply #16

Fluss

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I let that link here, really interesting and informative : https://renderman.pixar.com/stories/cars-3

Incredibly interesting! Worth it for the Close up pixar renders haha.

If you read carefully, it's not about close-up but on the contrary for details preservation when an object is far away from the camera. :-)

2018-12-05, 23:20:55
Reply #17

Jpjapers

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I let that link here, really interesting and informative : https://renderman.pixar.com/stories/cars-3

Incredibly interesting! Worth it for the Close up pixar renders haha.

If you read carefully, it's not about close-up but on the contrary for details preservation when an object is far away from the camera. :-)

Good point well made

2018-12-07, 10:34:47
Reply #18

David Males

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Yeah, I would highly suggest avoiding <1 blurring in Corona, it will eventually lead to some sort of visual artifact at arbitrary combination of resolution & glancing angle when you least expect it. It will give you the result you want in one moment and that produce total artifact in slightly changed angle/resolution.
To make CoronaBitmap more useful, a totally different algorithm should have been introduced as high-quality alternative.


Hey Juraj, just noticed this advice of yours - this applies only for normal/bump maps, correct? I mean 99% of people is using 0,01-0,1 blur on other textures to get the detail..
Great stuff anyway! Looking forwards!)

2018-12-08, 15:19:20
Reply #19

Juraj

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Try using 0.01 on already sharp bump/normal map high-res texture, then render said render in high-res (5-8k) and you will start to notice unwelcome surprise at many grazing approaching angles :- ). It's not pretty...

Then again, most people just use all sorts of crap bitmaps in bump, and if you render under small-to-mid res, bitmap filtering will literally erase ton of detail.

There really isn't one good value because it just depends on so many factors. 0.01-0.1 might give you better results in some cases but provide poor issues in other. With default filtering you're at least safe. I can't afford to send render to high-res final and then look in the morning and notice artifacts.

We need better bitmap filtering that doesn't need any sort of tinkering. Something that would finally give CoronaBitmap a reason to properly exist :- ).
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2019-02-01, 19:08:34
Reply #20

Fluss

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I wonder if Fstorm is able to sample bump so good, just because in the video was used its own noise shader? It might be that this trick won't work with regular noise or bitmap texture.

I wondered this too. At same though, someone told me they integrated this ? http://www.cs.ucsb.edu/~lingqi/publications/paper_glints3.pdf

The benefits of that go way beyond anisotropy alone. It simplifies shader creation and gives super accurate result regardless of resolution. Would be super nice to have that.

Juraj, finally took time to plunge a bit deeper in the paper you linked here and damn yeah! That's really cool!

2024-02-20, 15:46:39
Reply #21

lupaz

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I wanted to bump, no pun intended, this thread and see if this will ever be possible in a render engine like Corona.
Is it even possible with Vray CPU or GPU?

What I'm talking about is to have a bump map to create brushed effects like in real life, the way Fstorm does it.

2024-02-21, 11:41:23
Reply #22

Aram Avetisyan

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I wanted to bump, no pun intended, this thread and see if this will ever be possible in a render engine like Corona.
Is it even possible with Vray CPU or GPU?

What I'm talking about is to have a bump map to create brushed effects like in real life, the way Fstorm does it.

To create a brushed metal material, even with extreme close ups, is absolutely possible with Corona (and any modern render engine I believe). It just takes artistic control and depends on how "deep" you want to go. Simple answer will be to use texture with extreme detail, and turn off the texture filtering, so all the detail is taken into account as much as possible (0.01 filter value for Corona). But this can cause heavy flickering of the surface in case of animations. You just have to try it once and see how it "feels". This is the reason textures are filtered by default to be safe.
I know most Corona users do stills, so you are absolutely fine to just disable filtering for textures if you want (even for all of them).

The technical part here is mostly about texture filtering, which different engines do differently or just have different control over it, in connection with the host app as well.
This has actually been to some degree covered by the new "Roughness modulation" filtering mode for CoronaPhysicalMtl - if you use extremely detailed texture for bump, it will turn out to be anisotrophy (how it works in real life). "Roughness modulation" will understand how much of the texture as bump/normal (much calculation) should be considered, and how much of it can be treated as roughness (less complex calculation), depending on the distance from camera (think of it as condensing 1000 pixels of texture into 10 pixels in render resolution). But as it takes much effort and very detailed textures, that is why renders engine have separate, more convenient control for it, to get perceptually the same effect.
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2024-02-21, 21:35:58
Reply #23

lupaz

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Thank you.

Here I did a test in Corona and Fstorm.
250 passes with Corona.
To me it looks like the detail of the texture is lost or clamped in Corona (first image).
In both the mapping and texture are the same.
In both cases I used zero roughness.

The archive is here:
https://we.tl/t-jOyW2VVMkE
« Last Edit: 2024-02-21, 21:46:20 by lupaz »

2024-02-22, 10:14:40
Reply #24

Aram Avetisyan

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Thank you.

Here I did a test in Corona and Fstorm.
250 passes with Corona.
To me it looks like the detail of the texture is lost or clamped in Corona (first image).
In both the mapping and texture are the same.
In both cases I used zero roughness.

The archive is here:
https://we.tl/t-jOyW2VVMkE

I don't think that the detail is lost in Corona.
Even if the material setup is virtually the same, render engine may have different calculation algorithms.
I would say this is simply about artistic control - getting the look you want in any render engine.
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2024-02-22, 14:44:26
Reply #25

lupaz

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Thank you.

Here I did a test in Corona and Fstorm.
250 passes with Corona.
To me it looks like the detail of the texture is lost or clamped in Corona (first image).
In both the mapping and texture are the same.
In both cases I used zero roughness.

The archive is here:
https://we.tl/t-jOyW2VVMkE

I don't think that the detail is lost in Corona.
Even if the material setup is virtually the same, render engine may have different calculation algorithms.
I would say this is simply about artistic control - getting the look you want in any render engine.

Since you guys make videos a lot, I'd be interested to see a video dedicated specifically to creating realistic clean metallic surfaces. Not cylinders but flat surfaces. Thanks.

Edit: Specifically how to remove this clear reflection without using roughness. see attached.
EDIT 2: And without using fake anisotrophy
« Last Edit: 2024-02-22, 15:31:22 by lupaz »

2024-02-22, 17:03:23
Reply #26

pokoy

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Edit: Specifically how to remove this clear reflection without using roughness. see attached.
EDIT 2: And without using fake anisotrophy
Yeah that area is not looking good, same for the harsh reflection/highlight cutoff on the right box. What would be needed to get rid of these?
At least similar fireflies are there in Fstorm too, these would be my main concern in both renderers, wonder if they'd clean up without clamping highlights.

2024-02-23, 16:40:07
Reply #27

lupaz

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Edit: Specifically how to remove this clear reflection without using roughness. see attached.
EDIT 2: And without using fake anisotrophy
Yeah that area is not looking good, same for the harsh reflection/highlight cutoff on the right box. What would be needed to get rid of these?
At least similar fireflies are there in Fstorm too, these would be my main concern in both renderers, wonder if they'd clean up without clamping highlights.

To be fair with Fstorm I only rendered that for 1000 Fstorm passes (not much), while I rendered the corona version for 250 Corona passes (should be enough).
I'm pretty sure Fstorm would eventually clear the fireflies but I don't think corona could.