Author Topic: New Corona Physical Material (PBR) playground!  (Read 19738 times)

2021-04-08, 03:23:00
Reply #150

cjwidd

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Not having any visibility into the actual mechanisms controlling the sheen layer - a sort of analog to the falloff map - it seems like:
  • 'glossiness' parameter is sort of controlling the "coverage" of the sheen effect
  • 'amount' parameter is sort of controlling the "opacity" of the sheen effect
Curious if that is a reasonable way of thinking about it(?)
« Last Edit: 2021-04-08, 03:33:05 by cjwidd »

2021-04-08, 10:08:57
Reply #151

cjwidd

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I spent a lot of time experimenting with the new 'sheen layer,' and for some reason I had it in my head that the sheen layer was intended as a sort of catch-all method to address fabric shading in Corona Renderer without falloff maps; to obviate the need for falloff maps in fabric shading. I think that was a gross misinterpretation on my part because the sheen layer really is not flexible enough in its implementation to address very many fabric types - it is equipped to address velvet, satin, silk, etc.

2021-04-08, 11:42:54
Reply #152

GeorgeK

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I spent a lot of time experimenting with the new 'sheen layer,' and for some reason I had it in my head that the sheen layer was intended as a sort of catch-all method to address fabric shading in Corona Renderer without falloff maps; to obviate the need for falloff maps in fabric shading. I think that was a gross misinterpretation on my part because the sheen layer really is not flexible enough in its implementation to address very many fabric types - it is equipped to address velvet, satin, silk, etc.

The primary goal of Sheen is an easy simulation of the effect of subsurface scattering in the fibers, so any further customization options would highly likely deviate from sheen itself (and physical correctness). With that said we are always open to improvements or further feature requests that could potentially make it much better/flexible.
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2021-04-08, 12:03:15
Reply #153

GeorgeK

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One thing which was always a difficult approach for me was, light behind frosted glass.

In the attachement you can see an example of Roughness 0 to Roughness 0.01.
I quite not understand why a frosted glas can block soo much light. I understand that at some point like 0.4-0.6 you lose a lot but why already at 0.01? It seems like it clamps right above 0.

This behavior is also happening with the LegacyMtl. Can somebody maybe explain if this is intentional? Thank you.

I am afraid this is a known issue with fake glass (no caustics enabled) but also a bug that we are planning to address.
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2021-04-09, 00:37:34
Reply #154

cjwidd

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The primary goal of Sheen is an easy simulation of the effect of subsurface scattering in the fibers, so any further customization options would highly likely deviate from sheen itself (and physical correctness).

Is that to say the sheen layer is meant as a sort of artistic embellishment, or is it offering a physically correct look by default?

2021-04-09, 16:16:08
Reply #155

Juraj

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The primary goal of Sheen is an easy simulation of the effect of subsurface scattering in the fibers, so any further customization options would highly likely deviate from sheen itself (and physical correctness).

Is that to say the sheen layer is meant as a sort of artistic embellishment, or is it offering a physically correct look by default?

Truth be told I don't know myself how to use it properly :- ).

One important aspect I found, is that it's good idea to "map" the intensity of the effect, instead of using pure numerical value. No fabric is smooth enough to create the sheen effect uniformly, the effect follows the structure so the structure needs to be converted into map that drives the effect intensity.

How that conversion should be done, is purely artistic interpretation. It's one of those "fake, but not fake" approaches to PBR that is necessary because real fabric is incredibly complex and mapping shader to a flat plane does pretty bad job most of the time, making "pure" PBR approach impossible. Just like Ambient Occlusion being mapped onto Albedo is necessary for most scanned materials (like rocks, grass, etc...)
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2021-04-09, 22:43:47
Reply #156

cjwidd

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One important aspect I found, is that it's good idea to "map" the intensity of the effect, instead of using pure numerical value. No fabric is smooth enough to create the sheen effect uniformly, the effect follows the structure so the structure needs to be converted into map that drives the effect intensity.

Ah I see, this is very helpful, thanks!

2021-04-09, 23:15:56
Reply #157

GeorgeK

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One important aspect I found, is that it's good idea to "map" the intensity of the effect, instead of using pure numerical value. No fabric is smooth enough to create the sheen effect uniformly, the effect follows the structure so the structure needs to be converted into map that drives the effect intensity.

Ah I see, this is very helpful, thanks!

Sheen also cooperates very well with displacement, it also seems to do lovely for certain fruits (or seeds) that have fuzzy skin :).
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2021-04-10, 01:03:23
Reply #158

cjwidd

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it also seems to do lovely for certain fruits (or seeds) that have fuzzy skin :).

Would love to see some example renders of this effect in action if any are available

2021-04-11, 16:39:34
Reply #159

GeorgeK

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it also seems to do lovely for certain fruits (or seeds) that have fuzzy skin :).

Would love to see some example renders of this effect in action if any are available

So far I've been applying Sheen to peaches and some watermelons, works great with Kiwi too but needs some more tunning along with scattering.
The biggest benefit as I see it, it's that I had to only work with 60k fibre strands instead of 600k for Cscatter, the rest of the colouration that I wanted is coming from Sheen. I will post some examples again at a later date for release highlights.

But for the moment, in the Kiwi case, I exaggerate the effect a bit to notice its strengths and weaknesses on the model, a mask always helps:
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2021-04-12, 23:03:51
Reply #160

cjwidd

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Really looks good +1

Any chance you could do a 5-10min walkthrough of how you approached the shading of this asset, e.g. fibre modeling, scattering, shader setup, etc.

2021-04-14, 12:22:01
Reply #161

GeorgeK

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Really looks good +1

Any chance you could do a 5-10min walkthrough of how you approached the shading of this asset, e.g. fibre modeling, scattering, shader setup, etc.

Surething! I will try and make a short guide-approach :), I will also fix scatter base inconsistency with sheen (highly likely this will result in a feature request).
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2021-04-15, 08:55:52
Reply #162

cgiout

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Hi guys. Any chance to have also an upgraded material library with brand new physical materials in the future?

Thanks
Raf

2021-04-15, 09:05:21
Reply #163

cjwidd

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Surething! I will try and make a short guide-approach :), I will also fix scatter base inconsistency with sheen (highly likely this will result in a feature request).

Nice, looking forward to it!

2021-04-15, 09:28:33
Reply #164

GeorgeK

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Hi guys. Any chance to have also an upgraded material library with brand new physical materials in the future?

Thanks
Raf

This is also being addressed, please stay tunned.
For solutions and troubleshooting please visit - [link]
Please submit your tickets here - [link]