Selection with GBuffer in combustion

#1

Hello.
I’m very new to combustion but after some manuals I stil con figure this one out.
For instance…I have an RPF and I want to apply a color correction that affects only the more distante areas but I can’t figure out how to select based on the z buffer.
Another similar problem is selecting based on material Id since that channel is not antialiased the coverage channel as to be considerer (object Id selection operator already have this).
I think I have to select material Id (ok…theres a component for that) but then I have to multiply this selection by the coverage channel…right??
So…basicaly I’m can’t make a selection based on gbuffer channels.
And of course…I don’t really know how to work with the various layers in each of these gbuffer channels (the coverage for example…)
Can someone give me some help on this!?
Thanks

#2

I believe that it isn´t possible you to select directly from the Zdepth channel in combustion, more using operators to 'extract" the zdepth of footage or layer and using it as map for Set Matte operator for example can be useful for color correction. You are using the G-buffer extract?

#3

when you import a RTF file you have 3 options:

merged
grouped
nested

When you choose merged your objects will be seen as one footage.
you cant really do an easy color correction to further or closer objects,

its much easier when you choose grouped or nested… all your objects are then different footages. so you could apply different effects on each footage.

#4

Hello
I tried using the set matte but I’m not sure how to use it for this affect.
I just apply the color correction in the setmatte component and then put it on top of the original, right??
Am I missing something or this could be much simpler if there was a “set selection” component!?
Is there any plugin for this?
Thanks

#5

The Set Matte use other layer or footage as alpha channel for the “principal” input. You need extract the Zdepth pass, use the Show G-buffer operator, and connect it to set matte, use operators like invert and brightness and contrast for control the matte. You can select individual objects using the extract G-buffer and edit these objects, after user layers to compose

#6

The compound channel selection works for this. Set the input to luminance and choose the Zdepth footage. If you want to have finer control render out the zdepth in 10 or 16 Bit.
You will get more grey steps than in 8 Bit.

#7

Hi. Thanks
This Compound channel selection is definetly the way to go.
It doesn’t have luminance nor value though…only R,G,B and alpha.
I just used a color component since the zdepth is just a grey scale
Thanks again

#8

og

You can get the same results using the Set Matte, but you it will get one alpha channel not a selection, each method has its advantages and uses:thumbsup:

#9

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.