Hairs with VOP 'cast shadow' OFF = render time increase

[circus studio]

Hello,

In Maya, I have a hair system from Yeti and when I put a 'vop' on the hair shape with 'cast shadow' unchecked my render time explode.
If I make the hairs more transparency (opacity < 0.05) it's faster than 'cast shadow' off in the vop.
Is it normal for you?

Thank you,

Best regards

Edouard

Vray next 1.1 used.

[vlado]

Can you share a scene that we can profile? I'm not sure yet if it's normal or not.

Best regards,
Vlado

[Zdravko.Keremidchiev]

The render time difference is expected. This happens due to ray calculation accumulation. For example, if Cast Shadows is enabled a ray calculation will stop in the first hair it hits, but if Cast Shadows is disabled the ray will go through all the hairs on his way and will cause many more calculations. That is why if you reducing the hair count will reduce the time difference.