VrayDisplacementMod subdivs post 3.30

[windowlicker]

I'm having some problems with huge memory consumption (and loooong render times) when using displacement after installing 3.30.

After opting to use the "automatic" subdivs setting for vray, the displacement subdivs are grayed out. This just doesn't feel right. It's a very different kind of subdiv, afaik, which doesn't affect the DMC in any way. Therefore it should still be able to set manually.

It also seems impossible to get it back. Clicking "use local subdivs" in the render settings changes nothing, and the disp. subdivs box is still grayed out.

What do?

[vlado]

After opting to use the "automatic" subdivs setting for vray, the displacement subdivs are grayed out.

There's no relation at all between displacement subdivs and the sampling subdivs. The displacement ones are certainly not greyed out when you click through the "use local subdivs" option, at least not here.

The displacement subdivs are only greyed out if you use 2D displacement (because they are irrelevant in that case), or plain 3D displacement (because V-Ray has always ignored them, even in older versions, all the way back to V-Ray 2.x). They are only valid for subdivision displacement.

So I think the problem is somewhere else. If you turn off displacement globally, does memory usage go down?

Best regards,
Vlado

[windowlicker]

Alright, thanks for a quick response.

In this case, I use 3D displacement. Haven't noticed that box being grayed out before 3.30.
But the help file is wrong? It states "Max. subdivs – this controls the maximum sub-triangles generated from any triangle of the original mesh." Found here.

Everything works fine if I turn displacement off globally. Or rather, the renders finish in time.
I submitted renders with displacement on and off to our farm, so I can't give you the numbers on mem usage right now. All I know is that the renders that stuck had maxed out on mem. Some were struggling with the IM calc, even after 10 hours! Some were rendering the final image, but very slowly. I will do further tests to check mem usage when I have time.

[super gnu]

sounds like you have your max edge length too low. try turning it up. obviously too high and it will look crap.

another good trick is to stick a "subdivide" modifier on the mesh before displacing. divide it relatively finely. gives less work to the displacement modifier to do.

[svetlozar.draganov]

In this case, I use 3D displacement. Haven't noticed that box being grayed out before 3.30.
But the help file is wrong? It states "Max. subdivs – this controls the maximum sub-triangles generated from any triangle of the original mesh." Found here.

Would you please give us more information about why do you think that the help file is wrong?
That value wasn't greyed out in previous versions - that is correct.

All I know is that the renders that stuck had maxed out on mem. Some were struggling with the IM calc, even after 10 hours! Some were rendering the final image, but very slowly. I will do further tests to check mem usage when I have time.

This is actually a normal behavior when the RAM is filled up to 100%, the render becomes extremely slow or the scene crashes with Undandled Exception error.
Try to decrease Displacement settings like super gnu suggested.