Vray displacement error when adding subdivision

[mans.larsson79PXK]

When trying to render my displacement (32-bit exr) in Vray everything looks okay. (first image)
However, as soon as I apply the subdivision attribute to my mesh, all the negative information in my map gets "clipped" by a smooth, non-displaced, version of the mesh. (last image)
Any ideas as to why this is happening?

[damaggio]

On your displacement EXR file attributes> Vray >Allow negative colors should be enabled...see if that helped and do not filter texture.

[mans.larsson79PXK]

Thanks for your reply!
I'm sorry, I should have stated that I have tried that, but it doesn't make a difference.

[Christoph_Schaedl · Accepted solution]

are you using UDIMS or UVtiles..? in this case you have to set the displacement bounds by hand...

use 5 and minus 5 

[mans.larsson79PXK · Accepted solution]

Thank you!
I had thought about it, but since i couldn't set the value to anything negative I abandoned it.
Here is the work around I used to get a negative value (if there is a more convenient way of doing it I would love to know!)

[TKIO]

Hi mans.larsson79PXK

I have the same issue but am not sure  I understand your workaround.

What's the node between the 'multiplydivide' and the 'shadinggroup'? and what's the value you set in the 'multiplydivide' ? Thank you.

Jacques

[mans.larsson79PXK]

It is the shape node of the object that has the displacement applied to it.

Select the object, and click on "add selected node to graph" in the Node Editor.

Expand the shape node so you can see all of the attributes (make sure you have added Displacement control first and set "Displacement bounds" to "Explicit"). Find "Vray displacement Min Value"
Now create a MultiplyDivide node, and make sure the output is negative, so for example -1 x 5.
Connect the output of the node in to "Vray displacement Min Value"
Now the Displacements min value will be set to minus 5.

I hope that is clear 🙂

[TKIO]

Crystal clear. Thanks a lot!!

Jacques.

[rkdudxkdxkd]

Hi. It's been a long time ago.

But I found more simple way to fix that issue.

In Displacement control, you can control the displacement boundary.

1. Add Displacement control.

2. Change the Displacement bounds 'Automatic' to 'Explicit'

3. Input the number -5, 5 to Min value and Max value.

- You can put the number when you check out the color management.

- And HSV > RGB 0 to 1.0

- I don't know why -5, 5. I just saw that in the Vray official documents.

I've troubled with it for a day haha.

Hope it will be help to people struggling this issue. 🙂