Vray to nuke Velocity Tutorial

[reinaldomoon]

You can't really do this, because you don't have the full information about the object below. You can make a mask for the object above, and blur it with the velocity, but what you will use for a background? I suppose it is up to the compositing program to do some magic there and somehow blend the two objects in a more realistic way.

Yep, this is what we thought, but we don't know how fusion does it, and the cool thing is that looks almost like composited when working with separate layers with vectorblur. Really nice approach they have.
I expected Nuke to do this like fusion but at the foundry they classify it like a Bug, so must be they think it can be done, otherway they would say it will never work, so let's wait a bit and they'll found a way to fix it.

They replied me from the foundry and said it was known bug for some time

"Bug 15350 - VectorBlur does not work properly when object is on top of a stationary object"

In this case I would suggest to try RSBM and see if it gives you better result.

We tried but didn't work either, but thanks for the advice.

Sorry for coming back to you so late .... busy days.

[Morbid Angel]

I mean I know its a pain to separate the objects into layers, but in maya render layers aren't that bad...so its not the end of the world...not like in max anyway

[reinaldomoon]

I mean I know its a pain to separate the objects into layers, but in maya render layers aren't that bad...so its not the end of the world...not like in max anyway

Yeah.

The point is for example some Phoenix liquids we rendered which are twisting and overlapping itself all the time, or for example a character with arms moving in front of him.
You don't always have time to render 3D motion blur. The foundry should act somehow.



Jordi

[Morbid Angel]

Well I gave a quick experiment a try. It may just work for the fluids. Basically you would need to apply an erode/dialte node to the vector and erode it out a bit, then gamma correct the vector to clamp the edges a bit and that may just work, again it wont work on extreme blur, but on a small blur example it worked for me.

Also, Im not sure motion vector on the fluids is a good idea: I think blurring the semi transparent objects can be difficult with vectors, so you would be restricted to general blur of the volume. Why not use 3d motion blur?

[reinaldomoon]

Well I gave a quick experiment a try. It may just work for the fluids. Basically you would need to apply an erode/dialte node to the vector and erode it out a bit, then gamma correct the vector to clamp the edges a bit and that may just work, again it wont work on extreme blur, but on a small blur example it worked for me.

Also, Im not sure motion vector on the fluids is a good idea: I think blurring the semi transparent objects can be difficult with vectors, so you would be restricted to general blur of the volume. Why not use 3d motion blur?

We didn't have time for that.

But in the end worked quite well.

Thanks for the ideas, will test them for sure.

[Fredrik Averpil]

Thanks for sharing!