UV Pass/Render Element

[raxto]

It there some workaround how to render UV RenderElement correctly with DMC min/max subdivs 1/4 ?
UV RenderElement = samplerInfo + Extra Tex

thx
Rasto

[t.petrov]

Can I ask you to try to explain what is your problem a bit better?

[raxto]

DMC sampler is affecting all render elements.
But i dont wana affect color of ExtraTex.

Note: ExtraTex have filtering off.

DMC min/max samples 1/4, and TEST have jagged edges.


but when i set DMC min/max samples 1/1, TEST looks ok.

[bigbossfr]

It is because you need more sample for this renderElement.
The best is to create a renderLayers for this, set the AA to fixe, and render.

[raxto]

No, i don't need more samples than DMC 1/1 for this element.
And i don't wana use renderLayers, because i want use renderElement.

[bigbossfr]

No, i don't need more samples than DMC 1/1 for this element.
And i don't wana use renderLayers, because i want use renderElement.

The UV Pass need 32 float image with a lot of "samples" to get "clean" result when you use STMAP.
To do this, you have to separate and "over sample" this pass.

[raxto]

Anybody with real help or workaround ?

same problem here: http://www.chaosgroup.com/forums/vbu...ighlight=stmap

[Narann]

bigbossfr is right, let me explain:

ExtraTex have filtering off so only one sample will be used to determine the color of the pixel.
When you use DMC 1/1 the first sample is launched at the corner of each pixel. No random there. That's why it work.
But once you are in DMC 1/4, the first sample is no more launched at the same position from each pixel.
That's why, as bigbossfr said, you need to be in "fixed" sample to render a such case, because fixed sample.

You should read at this: http://interstation3d.com/tutorials/...yfing_dmc.html

Good luck!

[raxto]

I understand sampling problem, it's ok.

But i don't understand meaning of renderElements.
When you rendering renderElements like UVpass or DEPTH with DMC sampler of not fixed values,
then you can't render it correctly.

Am i right ?

thx
Rasto

[Narann]

I don't really know (I mean, I just think) how VRay launch it first pixel sample but yes, what you say is good.
It could be interesting to be able to "force" vray to launch the first sample of a pixel to the corner of it when using DMC. I don't know if it's possible by design but as DMC1/1 seems to have this behavior it's maybe possible.

Maybe vlado would have a better answer to this.

[raxto]

That's what i am waiting for, Vlado's reply.

[raxto]

Vlado ?

[vlado]

You will need to use higher min. subdivs for the Adaptive DMC image sampler; I can't think of any other workaround.

Best regards,
Vlado

[alainfx]

Hello,

You will need to use higher min. subdivs for the Adaptive DMC image sampler; I can't think of any other workaround.

Would it be possible to have an attribute on Extra Tex, that allow to override those DMC parameters ?
Because the current workaround is to add another render layer (with DMC Min and Max having exactly the same value), which is often tedious.

(we have exactly the same problem, trying to feed a Nuke ST Map with an UV pass generated by VRay)

Thanks.

[vlado]

No, I don't think so; it is a bad idea for a render element to take over the renderer's parameters - it can cause a lot of frustration and high render times (I remember at least several clients had issues with the "consider for antialiasing" option which they left on for point position passes). You can maybe use the post-translate python callback to modify the sampling parameters before rendering.

Best regards,
Vlado