Radial anisotopy

[boxfx]

In the attached scene I have a swirled, radial, anisotropic reflection on a round label. It works 99% perfectly, but where my rotation texture flips back from black to white at the 6 o'clock position, you can always see a line in the reflection. Does anyone have a suggestion on how to avoid this?

[jobigoud]

How about using a procedural version of this angular gradient? This way whatever location is sampled it should always resolve to one side or the other, instead of interpolating between the two as it's doing here.

[boxfx]

That should be the solution in theory, but in practice it doesnt work due to the srgb/linear interpolation of c4d's gradient. Left is the pixel based texture, right is the c4d gradient shader. The incorrect gamma input skews the anisotropy off into a curve. Gamma adjustments on a colour correction node cant fix it. Octane doesnt support the different c4d gradient interpolation modes (smooth, linear, cubic etc) so you can't fix it that way either.

[SSmolak]

How about blur a little gradient image on this skew or bake C4D nodde gradient ?

[boxfx]

If I bake the c4d gradient... then A, I still have the gamma problem with it bending the reflections, and B, that turns it into pixels internally, so Im back at my original problem of there being a seam at the start/end because the black to white transition will blend via sampling.

[aoktar]

That should be the solution in theory, but in practice it doesnt work due to the srgb/linear interpolation of c4d's gradient. Left is the pixel based texture, right is the c4d gradient shader. The incorrect gamma input skews the anisotropy off into a curve. Gamma adjustments on a colour correction node cant fix it. Octane doesnt support the different c4d gradient interpolation modes (smooth, linear, cubic etc) so you can't fix it that way either.

The attachment swirlcurve.png is no longer available

There's not any sRGB interpolation. Because it's not baking the gradient to images. It's using some OSL script to simulate the gradient and you can see the exported node in this picture.

[bepeg4d]

The OSL translation is setting the gradient interpolation to Cubic, so you need to export the material in .orbx from Node Editor, open it in Standalone to change the interpolation to Linear, save the material in LocalDB, and import it back in c4d:

In this way the interpolation is correct, and the gradient stays procedural.

Here is the .orbx mat:

RadialAnisotropyLinear.zip

(87.33 KiB) Downloaded 81 times

ciao,
Beppe

[jobigoud]

Does it need to go through the Gradient map? Can the gradient OSL be exposed as a separate texture, similar to the "Gradient generator" texture in standalone?

[aoktar]

Does it need to go through the Gradient map? Can the gradient OSL be exposed as a separate texture, similar to the "Gradient generator" texture in standalone?

Yes of course it can be used