View Full Version : render only a specific surface from the object

12-19-2016, 04:06 AM
Is it possible to render only one specific surface from an object which has more than one surface. Without rendering the whole scene?. As this should save me a lot of precious time.
what i mean is, if i have object with several material on it, and i want to render only one material of them as a separate pass.
is it possible, or any plugin can do that?

thank you

12-19-2016, 07:10 AM
TrueArt's Global Materials could help you slightly.

But I see issue with your true separate pass:
what if material is reflective, refractive, use any ray-tracing.. ?
If the all other surfaces you will make transparent, not visible to ray-tracing functions, then all reflections, refractions (or even shadows) will be gone, and not looking the way they would while normal rendering..

12-19-2016, 06:45 PM
If you are using Octane just select the Object ID pass in render layers. This will give you an extra render pass which assigns a color per surface. Then you can use that particular color as an alpha channel in your compositing program of choice.

12-19-2016, 09:50 PM
yes thank you
this is what i exactly did
i reduced all other materials opacity to 0%
separate the object on different layer
and the problem solved
although it took the same amount of rendering time as rendering the whole scene,
i thought it will take less time, because i am rendering only the wanted material
fortunately i don't have reflections, just a simple scene

thank you all

all done with octane

12-20-2016, 12:40 AM
Separate all of those materials as objects if you can. Not sure about what kind of object you have. But it is taking the same time because you are rendering with opacity. Separating the objects and either turning them off in the Scene Editor or Render Properties will do it. You can also on a per object basis select variations on the visibility in the scene, to cast shadows and not render for instance.

12-20-2016, 04:10 AM
And since you went ahead and made it a separate object, you can use the scene editor (new), go to the Property tab, click on the strip underneath it and choose 'Object' and then choose 'Render Flags'. You can then go down the list checking off unseen by camera for all the other objects.

12-20-2016, 04:21 AM
thanks guys
will try your approach. although i not sure what might cause unexpected dynamic behavior, but will try it any way