ID channel to mask the smoke

[themaxxer]

Is there a way to render a ID channel like MatID or MultmatteID for the smoke?
what I need is the smoke on a channel to make some color correction in post.

thanks for helping

best regards
themaxxer

[Ivaylo Katev]

I'm afraid there the answer is no.

Regards,
Ivo

[themaxxer]

very bad.
so I turn this into a request!
this is absolutely necessary!

best regards
themaxxer

[Ivaylo Katev]

a'm not sure about the details. you mean a separate render element for the smoke (or not?) but this part with the ID is slightly unclear. can you describe with more details what is the concept, if is not very complicated we can include it in the next service pack.

regards,
ivo

[themaxxer]

I would like to have the option to render a render element like an ObjectID for the PhoenixFD (smoke). It would be nice if it works with the MultiMatteElement from vray.

regards
themaxxer

[Ivaylo Katev]

we will include phoenix specific render elements at some point, but until now only the common render elements are supported in geometry mode.

regards,
ivo

[themaxxer]

this would be great. thanks. in the meanwhile I render a separate alpha channel.

best regards
themaxxer

[Paul Oblomov]

What about atmosphere channel ? It is not smoke or fire specific, but it can help in general.

[themaxxer]

hm, I have made a test but the channel is empty (black). how to use it?

best regards
themaxxer

[instinct]

Well this wont really work if i am not mistaken. If i got the request right you are asking for a kind of Multimatte for the different Channels ?
If so than this doesnt work too well as a pixel may containt a lot of differently weighted fragments for a lot of different channels (at different depths etc)
So when using a matte generated from the fragment weights of a specific channels you will also be color correcting the other Channels in your RGB of course.
So best would be render-elements for different channels that can than be plus-ed on top of each other to generate the RGB so you can treat them
seperately before plus-ing.

Regards,
Thorsten

[themaxxer]

I don't get it. all I want is a simple render element to cutout the smoke separately to make some post production. It is working on alpha channel too, so it should be possible to render to another channel too?!

best regards
themaxxer

[instinct]

K, the problem is that within a single pixel you might easily have smoke and fire generating the final pixel color. So if you cutout with a mask this pixel would still have the fire value in the RGB.
If you have fire/smoke on different renderelements you can really tweak them seperatly. Unless you render to deeppixel formats (and have the tools to work with the data) this is always an issue
sadly.

Regards,
Thorsten

[MathTheRender]

i got the request so; that he wants a the posibiltity to give Phoenix a map id so he has the posibility to do some nice color corrections in post with the matte from the map id.
since he "only" wants to tweak some smoke this would work fairly well. but as i understand thorsten, it would get a bit more complicated if there is a falme with smoke and so on...

so: isen't there any posibility yet to get sort of a mask or a map id for the smoke? i checked the help briefly but couldn't find anything...

im not a pro in compositing as others seem to be in here, but isn't that essential?

[Paul Oblomov]

how to use it?

It works like this in my Vray 12

[alkali]

Couldn't you sort of hack this by applying a Red-only shader to your fire and a Green-only shader to your smoke, and then masking them by channel in your post app?