Working with Green screens in Max?

[PiXeL_MoNKeY]

You will probably get a much better response posting this to the AE or Combustion Forums. Unless you are using Chroma Plugin (http://www.breidt.net/scripts/chroma.html) from Martin Breidt this really isn't that Max related. You are really going to have to use the Keyers advanced features to clean up the key. Keylight in AE is good for quick keys, but I like the power and control you have in Combustion's Discreet Keyer. I would strongly recommend trying the other forums for any keying related questions.

-Eric

[RichardBlank]

Thank you Eric.
But my question was not so much about the keying part, more about how you are supposed to work with the alpha channels in Max. And how you'll get them in to Combustion in neat way. Is rpf the answer? Pre-multiplied apha or not, or when?...
I just want someone with experience in handeling this kind of work to share their "exact" workflow. :)

... and I will post this question on the other forums as well...

[PiXeL_MoNKeY]

Your green halo could be a couple of things. How was it rendered out of AE (straight or premultiplied)? Did you set the bitmap alpha settings to be the same as the image? Did you try changing the bitmap filtering and the blur?

On how to get them into Combustion I would try RPF and not render your character in Max. Then in Combustion you can use the RPF options and 3D Layers to place the character where he needs to be in relation to the action. The biggest problem you will have is one person's exact workflow will be different for you as you are doing a different project with different content. Get into the programs and experiment that is how you will learn the best approach for you. There is never one correct answer, instead there are numerous options and you have to pick for the one that suits the job.

-Eric

[Ls3D]

Premultiplied alpha is the likely issue, please search AE premulti and you will find many threads.

-S

[michaeljr]

http://www.mjrworld.com/cgtalk/mJRshadowtestcomp1.avi - DIVX 2.7megs

http://www.mjrworld.com/cgtalk/mJRshadowtestcomp1.zip - 600kb

ok, this is a pretty crappy example and was never intended for public viewing. this was a quick test I did for a larger project I'm working on. (very embarrased to show this) As of yet there is no way to export your 3dsMAX lights into Combustion to get your shadow. So instead of doing the camera and lighting in combustion, it was just as easy to to is in MAX since I had to light the background anyway, just do it and create the shadows in MAX. As simple as using my pulled key footage slapped on a flat and let the MAX lights cast the shadows. Render those out as layers, take them back into Combustion and comp it.

as for you specific problem, if you are using DV it is not friendly to doing greenscreen. nature of the beast. this key I pulled is the best I could get without loosing much of my long, curly hair or the flappy, baggy pants I had on at the time (not going to wear those again they disappear to much) I do have a slight green edge because I forgot to change the edge to white to help blend in the background.

up to a specific point you can move the camera around until you destroy it with perspective.

so key it first in Combustion, then use that footage in MAX, do your background, lighting, shadows, effects, camera moves, peel those out as layers, go back to Combustion and then go from there. you will always have some sort of green edge or another color with DV. it's just the way it works and there is nothing you can do about it unless you use a more expensive 4:2:2 or 4:4:4 setup.

so don't worry about it, do the best you can with what you have and when you show it to people just say you did it with DV and they will understand.

[RichardBlank]

Thank you everyone! This is great help for me. :)

[RichardBlank]

so key it first in Combustion, then use that footage in MAX, do your background, lighting, shadows, effects, camera moves, peel those out as layers, go back to Combustion and then go from there. you will always have some sort of green edge or another color with DV. it's just the way it works and there is nothing you can do about it unless you use a more expensive 4:2:2 or 4:4:4 setup.

so don't worry about it, do the best you can with what you have and when you show it to people just say you did it with DV and they will understand.

Ok Miachael. Lets say that I have keyed it nice in Combustion and removed the all the green completly. What is the best way for me to get exact the same alpha result in Combustion and Max?

[michaeljr]

well since you pulled the key already in Combustion. just leave the background empty, render it out as a Targa 32bit with an alpha in it and take that into Max. apply that as a map, turn on it's alpha, slap it on a plane. and bingo. you have your actor floating in your 3d world. render out the elements you need, take those back into combustion, recomp them and then do your blurs and color changes there.

there is no reason to try to key in MAX, unless it's a realtime siuation where you want to view your actor in a 3d scene while you are filing it. MAX wasn't made for that.

[RichardBlank]

Thank you everyone, I finnaly got the result I wanted!


:thumbsup:

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