Scattering directionality for translucency

[Eneen]

Hi,

I don't have corona yet, but I'm considering switching from Maxwell.
I have question. In Maxwell it's possible to set asymmetry for thin-sss to achieve look of synthetic fabrics and leaves (with slight negative values). How can it be done in Corona?

Best regards.

[Ludvik Koutny]

Any examples with pictures would be helpful for us to understand what exactly you need.

That being said, in Corona, you can map both translucency (thin SSS equivalent) amount and color by any bitmap. So you can map translucency amount of leaf with a map of leaf veins, or translucency amount of fabric material with a map of fabric pattern, to have varying translucency amount across surface.

[maru]

Hi, here is an example of using translucency:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000515643

You can also download Corona demo. :)

[Eneen]

Here you can see two maxwell images with very simple material to illustrate thin-sss asymmetry (only clipping texture used). One has 0.0 and other -0.3. On first back of leaves are evenly illuminated, on other leaves on left side are brighter then on right. I hope that clarifies what I mean.

[Ludvik Koutny]

Oh yes. That's a simple translucency parameter in CoronaMTL.

[Eneen]

But will "scattering directionality" work for translucency with single plane geometry?

[Ludvik Koutny]

I guess you could map translucency amount slot with falloff map :) I doubt whatever directionality in Maxwell is, it enhances realism in any way.

[maru]

This looks similar to directionality in Corona's volumetric scattering effects. I also thought about faking it with falloff map.

[Eneen]

It is directionality in scattering, though in maxwell thinsss and sss work in really similar way. This IHMO will be hard to fake using falloff, as it is controlled by light-object-camera angle, not only object-camera.

[Ludvik Koutny]

It is directionality in scattering, though in maxwell thinsss and sss work in really similar way. This IHMO will be hard to fake using falloff, as it is controlled by light-object-camera angle, not only object-camera.

Could you post any real scene pictures where changing of directionality in thin SSS mode Maxwell material increases realism or improves the look? I am still having hard time understanding why would i want to ever use anything like that...

[Eneen]

@maru: it seems it can be done by adding some refraction with nd 1.0 and 0.1 gloss, but I have to test more.

[maru]

I'm afraid you should not use refraction for leaves/other objects with no thickness.