matte and phantom?

[robertoandrea]

Hi guys,

I have a simple question. I can't understand when i want to get render in mantra forced matte and forced phantom options. i get render separate every time for example if have destruction scene and if i want to get render that rbd, dust, debris, smoke etc. Do i need to put something forced matte and forced phantom in mantra settings? are they so important?

thanks...

[LaidlawFX]

Forced Matte allows you to purposely subtract that object from being rendered in effect blacking/clipping out that object from the render. The Forced Phantom does a very similar thing except, the object will contribute to bounce passes and reflections. So it will render as it is fully in the scene but be clipped out at the very end. Where as matte clips it out at the very beginning of the render. They really just matter for what types of render passes you want to send to comp. 

[robertoandrea]

these are just better to get render pass?

what if i don't have pass? do i still need them?

[davpe]

it is very simple man. you've got a scene and you've got some objects in it. now if you just want to plain render everything you see, there is no need to put anything into matte or phantom. but if you want certain objects to be invisible in your image but still you want to consider them for render computations, that's when you use phantom or matte. difference is just how they affect an alpha channel (matte cuts out the object from the rendered image, phantom doesn't). 

[LaidlawFX]

Yeah no need if you are not comping.