Getting black alpha when I render with VRayHairNextMtl transparency?

[shaneasimms]

When I take distance along strand from a VRayHairSampler node, and remap to black/white (effectively trimming the hair), then plug into transparency, the beauty renders as expected, but the alpha returns black in the transparent areas, even though there is geometry in that area that renders fine in the beauty. How can I fix this?

V-Ray Next for Maya v4.12.01.29159
Maya 2018.4.P07

[Morbid Angel]

I think I had this before - the transparency is inverted value of opacity, so black is 100% opaque and white is 100% transparent, try flip the ramp and see if that helps.

[shaneasimms]

I think I had this before - the transparency is inverted value of opacity, so black is 100% opaque and white is 100% transparent, try flip the ramp and see if that helps.

This is not the issue I'm having - the transparency is behaving exactly how I expect. The R, G and B channels render exactly how I expect them to, but the alpha has black areas where there shouldn't be any. This seems like a bug, as the transparent area of the hair should render what is behind it in the alpha, not cut it out, like a holdout.

[hermit.crab]

You are most likely reaching the maximum transparency levels and the background is returned instead. Try increasing the 'Max transparency levels' amount (Overrides>Materials) to a higher value and see if that solves the issue.