Hair alpha transparency

[damaggio]

I'm replacing the shaders on a Rippley's hair game model from Alien but i cannot get the alpha from the Targa to go into Opacity of the Vray mtl...I'm sure Vray can interpret an embedded alpha on targas...could anyone shed some light into this please?
Maya 2016 Vray 3.15 PC dual Titans.
Thanks.

[damaggio]

Actually I just resolved the issue, it's not connecting the Out Alpha... but Out Transparency to Opacity.

[damaggio]

Okay I'm back again with a related problem, please look at the attached jpg, I have one Vray setting that is fast for preview GI is enabled, but whenever I choose a different method Adaptive, Progressive or something else it seems that my hair transparency becomes inverted, I just can't pin point the setting area that is giving me this issue.
Please take a look and see what could be wrong here.
Scene is affected only by the Vray render settings , no changes are made to shaders nor textures.....Targas are being used here.

[vlado]

Which exact V-Ray build? Can you post some simplified version of the scene so that we can take a look?

Best regards,
Vlado

[damaggio]

Thanks Vlado, yeah I can but in the morning, is late here in LA and i'm shutting it off.

[damaggio]

Here Vlado, I Archived the reduced file, see if you can troubleshhot this one.
Thank you.

[damaggio]

And here's a settings comparison I was trying to pin point the differences...

[damaggio]

And my Vray version is 3.15 windows 7 maya 2016.

[yolov]

Which 3.15 build are you using? Can you get us the date and build number (it's printed in the maya output window right after vray is loaded on Maya startup)?

[yolov]

Seems to be the secondary ray bias (vray tab > global options advanced). Set it back to 0 and it will render fine.

[damaggio]

Great Alex , that was it, setting to zero resolved, although I don't know what secondary ray bias does, i'll check the documentation , so it's not a bug on this attribute right?...and why one would need to raise that value beyond zero...don't know how I mistakenly set to 0.100 .
My version is V-Ray: V-Ray for Maya version 3.15.01, revision 26541 from Dec 13 2015, 07:20:18
Thanks for the help guys.

[Svetlozar Draganov]

Secondary Rays Bias helps a lot in scenes with overlapping faces, please check the examples bellow:
http://docs.chaosgroup.com/display/V...ondaryRaysBias

If the scene renders fine(no artifacts from overlapping faces) it is recommended to keep this value to 0.

[damaggio]

That's great Svetlozar, makes more sense now, I really appreciate the link.
Cheers.