glossy reflection

[urbanite]

Hi

I do not why but glossy reflection in some vray materials in the scene are taking a lot of time to render. I took some tests and two materials with exactly the same settings in reflection and glossiness slot but different diffuse (material vs color) produce very different rendering times - color in diffuse slot (for example aluminum look) is taking much much longer than wood material next to it.
VRay 2.0, IM (very high settings)+LC (store glossy reflection)
DMC min 1 max 8
color threshold 0.005
materials reflection sub 16
hdri and sun shadow 64 (IM store with irridiance map turn on)
Image resolution 4000x3000. Cropped version attached.
Huge part of this scene is covered with aluminum material and I was shocked how much time it is taking on 24 core machine compare to the parts where other materials were used and they had glossy reflection. I have tried different settings I have found on vray forum, tried BF but without success.
Any help much appreciated.
Regards

[tricky]

Not sure I understand entirely, but glossies can take quite a while to render. Have you tried interpolated glossies on the 'slow' materials? (then you have IRmap like sampling controls)

[Neilg]

Turn the reflection depth down on that material.

[3DMK]

Hi

I do not why but glossy reflection in some vray materials in the scene are taking a lot of time to render. I took some tests and two materials with exactly the same settings in reflection and glossiness slot but different diffuse (material vs color) produce very different rendering times - color in diffuse slot (for example aluminum look) is taking much much longer than wood material next to it.
VRay 2.0, IM (very high settings)+LC (store glossy reflection)
DMC min 1 max 8
color threshold 0.005
materials reflection sub 16
hdri and sun shadow 64 (IM store with irridiance map turn on)
Image resolution 4000x3000. Cropped version attached.
Huge part of this scene is covered with aluminum material and I was shocked how much time it is taking on 24 core machine compare to the parts where other materials were used and they had glossy reflection. I have tried different settings I have found on vray forum, tried BF but without success.
Any help much appreciated.
Regards

DMC min 1 max 8 - This looks like the setting that makes the difference in render times for you materials.

Here's my theory on it--
A texture map has a lot of noise in it.
A flat colour has no noise in it.

Vray is taking your AA to the max samples [8] on the metal as Vray sees much more noise in the reflection as it is blended with a diffuse colour with no noise. That is: reflection noise is more prevelant when mixed with a noisless diffuse.
Because wood tex has lots of noise Vray expects the end result of mixing reflections & the diffuse to also have a certain amount of noise, so less AA subdivisions are used

Hope this helps