Ignore render elements on objects with matte obj/-1 alpha

[Neilg]

Quite often we render passes by setting everything else to be a matte object and rendering it on it's own (glass, fur, fine displacement things etc) but i've noticed that it calculates it over the entire scene and can add a couple of hours to the rendertime of a still just to do the matte/-1 parts of the image.

We've often got vray dirt in an extra tex and reflection/refraction elements set up, so having to calculate these over 90% of an image which we don't want to use adds a lot.

We already use regions and some workarounds, but it'd be nice not to have to worry about it.

[tashko.zashev]

Hi,

I think this could be avoided with few settings, especially for this case.
Reflection/Refraction amounts of the matte surfaces (Wrapper material) can be set to "0" in order to exclude them from the calculations and render elements.
Forthe AO pass, you can unckeck "affect matte objects" option in the V-Ray ExtraTex.

[Neilg]

Forthe AO pass, you can unckeck "affect matte objects" option in the V-Ray ExtraTex.

Never even noticed that box before, huh. Thanks!

[m_hinks]

Hi,

I think this could be avoided with few settings, especially for this case.
Reflection/Refraction amounts of the matte surfaces (Wrapper material) can be set to "0" in order to exclude them from the calculations and render elements.
Forthe AO pass, you can unckeck "affect matte objects" option in the V-Ray ExtraTex.

Regards the Wrapper setting, that could be very time consuming if you have many materials, could that same setting be added (if its not there already!) to the object properties, then you could make the change once when setting them to MS in the first place?

Just found the "affect matte objects" and has just saved me hours!!

Mark

[tashko.zashev]

Hello Mark,

Both, Wrapper material and Object properties should have similar options, thought.
Also you can see this script here, it's very useful:
http://www.chaosgroup.com/forums/vbu...aterial+script

[m_hinks]

Yes I use that script a lot. So which option should be changed if doing to via the object properties?

Thanks

[tashko.zashev]

If no Reflection/Refraction are required to be shown or calculated over the matte surfaces, their amounts in the V-Ray object properties window could be set to zero.

[m_hinks]

Ok, and that will also remove the matte objects from the elements?

[Neilg]

It does, I just did it.
I also checked on 'no GI on other mattes' and I think that removes the matte objects from the GI pass - i'll have to test if it does anything else funky. Works fine for what i've just done though.

They still show up in z-depth & rgb elements but they dont take any time to render anyway.

[m_hinks]

Just done some tests, and I tried leaving all the Vray object properties, and just setting the matte objects to not visible to camera on the max object properties, and it has a very similar effect. And can use the cast/receive shadows to remove those, the mattes still render correctly in reflections of other objects. And the mattes are not in the alpha, so that might be a better option?

I'd be interested to hear others views.

Edit;
This option is good for a scene with for example a load of glass that you want objects reflection in, but not render the objects. If you reverse the setup, and have say traffic in a MS environment, you would want shadows reflections etc affecting the MS environment, so it looks like they are both good but for opposite situations.