Primary visibility control with maya hair

[xoy]

it appears that vray for maya has problem with 'primary visibility' attribute. either from maya's own shape node or from extra 'vray object property' node, turning off 'primary visibility' leaves strange 'black hole'(alpha area is completely black) that partially represents shapes of some of the selected hair systems. the rest of render visibility attributes (such as 'visible in reflection', 'cast shadows' etc.) doesn't seem to be a problem. does anyone have similar experience? i'm on maya 2012 with vray 2.20.01 on windows 7.

[xoy]

it obviously only happens with 'some' of the hair systems. somehow in my case the 'clump width' attribute of maya hair has something to do with it. i have no idea why but when i set it to zero, then no artifact is there. vray odd.

[yolov]

Hi,

I don't think I fully understand what the problem is. What is it exactly that you're trying to achieve by doing this? With a clump width >0 there are shadows cast from the hairs when they are not primary visible, other than that, we can't reproduce this. Is it possible to send us a scene?

[vlado]

it appears that vray for maya has problem with 'primary visibility' attribute. either from maya's own shape node or from extra 'vray object property' node, turning off 'primary visibility' leaves strange 'black hole'(alpha area is completely black) that partially represents shapes of some of the selected hair systems. the rest of render visibility attributes (such as 'visible in reflection', 'cast shadows' etc.) doesn't seem to be a problem. does anyone have similar experience? i'm on maya 2012 with vray 2.20.01 on windows 7.

In the V-Ray settings, increase the max. transparency levels until the issue goes away.

Best regards,
Vlado

[xoy]

i'm just trying to have separate reflection pass. anyway, i tried to increase the max transparency levels up to 100 then stopped. now with your suggestion i went higher and found the problem disappears around 130 in my case. i just didn't think that i would need such a high number for my usual cases. thank you Vlado.

[xoy]

on further tests it appears that high 'max transparency levels' alone can't fix this issue. in some cases, i also had to increase 'global max depth' very high with vray hair shader disconnected altogether. then i'm rendering maya hair with maya's own shading control instead. i still haven't found reliable reflection pass method with various settings of vray hair shader (translucency used/not used, transparency used/not used etc. within the shader). this artifacts don't seem to appear with mental ray for example. well they have other issues.

[Zdravko]

Is it possible to send us a scene with that issue to: support@chaosgroup.com
Please mention this thread in your e-mail.