Dear friends,
we present a small advance in Thea material system, useful for those that aim for extra fine details when rendering.
This advance is about the coating absorption that can be wavelength dependent. The central idea is that the user defines now the absorption color at certain depth inside the coating (typically, 100 micro meters) using a standard color/texture control. This color becomes then the dominant one for any reflections coming from layers underneath.
Since the actual distance traveled by the reflected rays varies with the angle, the colored absorption creates a subtle but still observable effect where there is a simultaneous hue and saturation shift. The effect is "indeed there in real life" and can be seen in cases like metallic car paints and tinted wood varnish.
I attach two renders of a model, where you can see the transition and hue shift with viewing angle. This is more evident as you see nearer the edges of the car.
Best wishes
Colored Coating Absorption
- PixelMango
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"Fresnel" option in Thea Materials?giannis wrote:Dear friends,
we present a small advance in Thea material system, useful for those that aim for extra fine details when rendering.
This advance is about the coating absorption that can be wavelength dependent. The central idea is that the user defines now the absorption color at certain depth inside the coating (typically, 100 micro meters) using a standard color/texture control. This color becomes then the dominant one for any reflections coming from layers underneath.
Since the actual distance traveled by the reflected rays varies with the angle, the colored absorption creates a subtle but still observable effect where there is a simultaneous hue and saturation shift. The effect is "indeed there in real life" and can be seen, typically, in case of metallic car paints.
I attach two renders of a model, where you can see the transition and hue shift with viewing angle. This is more evident as you see nearer the edges of the car. Best wishes
- Rombout
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We also get a fresnel ramp texture, did you see other preview?
I believe Thea already uses Fresnel, but now we can manually tweak it with the fresnel ramp texture.
This effect however is what happens when color is seen through a coating at certain angles. Its something different than fresnel i think, not sure here.
I believe Thea already uses Fresnel, but now we can manually tweak it with the fresnel ramp texture.
This effect however is what happens when color is seen through a coating at certain angles. Its something different than fresnel i think, not sure here.
- giannis
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Yes! It is a small addition that is another texture controlled by thickness.Rombout wrote:Is this a addon to the current coating? this also had something about wavelength or thickness
This is not related to Fresnel curve tweaking but to absorption. It has an effect when there are additional layers under the absorving coating. The reflectance of those layers under the coating is then modulated by a combination of the absorption map + thickness + absorption physical formulas.
Best wishes
Science may limit knowledge but should never limit imagination - Bertrand Russell
- Rombout
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Ive tried the current absorption couple times never got it to work or quite understand well how it worked. The manual isnt sufficient in that i believe. Coating layer also has absorption function, is this sort of the same function than?
- giannis
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It is part of the new coating description. Patrick will make a small presentation with upcoming release.Rombout wrote:Coating layer also has absorption function, is this sort of the same function than?
Best wishes
Science may limit knowledge but should never limit imagination - Bertrand Russell
- giannis
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If I am not mistaken, the dominant color on the car comes from the absorption itself; it is not the color of diffusion or reflectance. I will check with Patrick, whether he can quickly make a render without the absorption but my expectation is that you will see a more "flat" gray coloring of the car.GreenUser wrote:Perhaps a picture of the car without the new feature next a picture with the feature on would help show off what it's doing?
Best wishes
Science may limit knowledge but should never limit imagination - Bertrand Russell
- patricks
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on the yellow/orange Lamborghini car, its only the absorption color that we are seeing as the underling diffuse color is white .... just like its made in reality
Greetings,
Patrick

Greetings,
Patrick
" Poets say science takes away from the beauty of the stars - mere globs of gas atoms.
I too, can see the stars on a desert night, and feel them. But do I see less or more ? "
Richard P. Feynman
I too, can see the stars on a desert night, and feel them. But do I see less or more ? "
Richard P. Feynman