Houdini hair scaling problems

[vurt]

Hi,
I have a problem with hair with a relatively small scale.
Because of the idea and optics, my head has to be around 3cm (which is not extremely small actually).
When I render the hair, the tips become fat, and the roots are regular. When I scale 10x it works fine.
I tried to flip the width ramp in hairgen, and it sort of fixed it, but the roots still a bit wrong. Other render engines are fine with that.
also the root and tip thickness in octane obj params does nothing.

hip file attached


thanks

[galleon27]

Just create a width attribute and set it to whatever you want or just go the the hairgen sop and edit the hair profile. Root and tip thickness in octane obj params does nothing because hairgen creates a width attribute that overrides whatever is in the obj parameters.

[vurt]

Just create a width attribute and set it to whatever you want or just go the the hairgen sop and edit the hair profile. Root and tip thickness in octane obj params does nothing because hairgen creates a width attribute that overrides whatever is in the obj parameters.

Thanks,
the hairgen creates the width attribute tho. I was trying to remap it with attribute remap, and it did not help.
did you use the left or right setup?
since one of them has the width flipped, this was the only way to fix the issue, but not completely

[galleon27]

Just create a width attribute and set it to whatever you want or just go the the hairgen sop and edit the hair profile. Root and tip thickness in octane obj params does nothing because hairgen creates a width attribute that overrides whatever is in the obj parameters.

Thanks,
the hairgen creates the width attribute tho. I was trying to remap it with attribute remap, and it did not help.
did you use the left or right setup?
since one of them has the width flipped, this was the only way to fix the issue, but not completely

I was using the geo1 network. It does seem like there is a bug. It doesn't render correctly. Maybe Juanjo can look into it. For now just go to the hair profile and set the first point value to something really low like 0.000001 instead of 0. It should work like that for now.

I've attached a screenshot of the width attribute and how it renders.

[juanjgon]

Yeah, perhaps Octane has problems with 0.0 width points. Can you please check if avoiding 0.0 widths helps with your problem?

Thanks,
-Juanjo

[vurt]

Yeah, perhaps Octane has problems with 0.0 width points. Can you please check if avoiding 0.0 widths helps with your problem?

Thanks,
-Juanjo

Yes, it seems like it does! How didn't I think about this solution

thank you guys!

[juanjgon]

In the next build, I've added some code to the plugin to avoid this problem:
- Fixed a problem in the hair rendering with very low "width" point values < 0.0001

Thanks,
-Juanjo

[vurt]

In the next build, I've added some code to the plugin to avoid this problem:
- Fixed a problem in the hair rendering with very low "width" point values < 0.0001

Thanks,
-Juanjo

Hey @Juanjo

Thanks for the hair fix.
But it broke everything. You've clamped too high.
I was using the temporary solution with adjusting the minimum scale. But my object is small, I am having 0.00000001 values and it was fine. So I can't go now below your minimum value.
Please fix. Meanwhile rolled back to previous build

Thanks

[vurt]

In the next build, I've added some code to the plugin to avoid this problem:
- Fixed a problem in the hair rendering with very low "width" point values < 0.0001

Thanks,
-Juanjo

Hey Juanjo,

Do I understand right, that if I want to use network rendering feature, this fix won't help, since Network rendering relies on Standalone/Network daemon, that has not this fix implemented?

Thanks,
D

[juanjgon]

It should work. This is a fix in the scene extraction code. The rendering should be the same in the local machine and in the network nodes.

Thanks,
-Juanjo