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lamar lowder avatar image
lamar lowder asked ·

Hair in "thick" mode showing segments when using Standard Hair

Hi,

I was recently working on some coral polyp shading and was having great success simply using the C4D hair module and Standard_Hair shader with Arnold parameters set to render "thick".

I've come to notice one problem and that is that you can see where the segments (hair-guides-segments) are in the hairs. I'm sure it's the segments because as I change the number of segments, the exact number of segments are seen in the render.

Have a look at this screenshot and let me know if there is a solution or workaround. I've tried using a standard shader but it just doesn't pull as good of a look as the hair shader. I've also tried setting hair to render as splines.

c4dtoahair
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Peter Horvath avatar image
Peter Horvath answered ·

The Sample rate does not really help here, it just defines the number of control points when exporting a NURBS curve. That's basically the number of segments in case of Hair. I hope we can come up with a fix in the core soon.

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lamar lowder avatar image
lamar lowder answered ·

OK. Found a workaround.

Hair-generate-circle with caps. Hair under connect object then allows Arnold to see the geometry.

Standard Hair still shows segments, however using standard surface set to thin walled and 100% subsurface gets a fairly nice result. The same gradient that controlled the mix of shaders along the hair also controls displacement to achieve the tiny bulbs at the end.

Again, nice result but still not as nice as using the Standard_hair shader.


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lamar lowder avatar image
lamar lowder answered ·

Hey Peter,

Just wondering if it's possible for Arnold to "see" the geometry "created" by the Hair system when set to something like Generate-Type-Circle (box, instance etc.)? Currently, with no Arnold parameters tag, Arnold only appears to default to ribbon renders

That might not only resolve this problem, it would also open up another level of functionality.


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lamar lowder avatar image
lamar lowder answered ·

Thanks for the reply, Peter.

I've tried everything at this point. Generate circle, spline, instances. Nothing seems to work.

Is it possible to add a "sample rate" control similar to the Arnold parameters tag when referencing a spline?

The Arnold hair shader is such a beautiful, unique shader, seems a shame to be limited like that.

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Peter Horvath avatar image
Peter Horvath answered ·

It's a known bug with the "thick" mode, I'm afraid, and I don't know any proper workaround. Maybe someone else has an idea?

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