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Blue Screen Grading - best practices for balancing blue screen plates.

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andrew smith
Blue Screen Grading - best practices for balancing blue screen plates.
on Sep 5, 2012 at 6:16:04 pm

Hello

I am curious about getting some advice on best practices for grading blue screen plates of footage to make everything match in Resolve V9. I am being told the AE or Smoke/Flame artists would be taking my graded blue screen footage and doing the key/comp/etc on that end - any advice on how best to manage this type of grade would be great - i will be getting 10-15 different blue screen plates of footage to balance and grade.

I believe they usually would use a smoke artist for this but are unable to on this job and wanted to do it in Resolve.

Curious what suggestions people may have for this type of Resolve work. I have had to do balancing before with footage that had different actors in front of a solid color wall (white, pink, etc.) but those were not to be keyed or composited afterwards - nonetheless I did find that type of balancing work alone to be pretty challenging seeing how after a few hours of grading actors in front of a white background the eyes start to do funny things with tints of blue or red and finding a perfect balance between shots so they all look the same.

Any help would be great.
Thank you
Andrew




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Joseph Owens
Re: Blue Screen Grading - best practices for balancing blue screen plates.
on Sep 5, 2012 at 6:59:19 pm

Depending on what the actual environment/content looks like or is supposed to represent, many times the purpose of green screen is to convince the audience that what they are seeing is a single composition. So after you have roughed in your plates, either by linking an alpha channel or extracting a matte from the blue/green/whatever foreground and connecting that to the appropriate plate layer, then you are simply grading to achieve what we always do.

Its very similar to grading around a foreground character or object with a secondary or power window, except the elements come from different sources/shots. It gets trickier if you are compositing action footage in front of synthetic scenery. Film grain, electronic noise, lens DOF, all these factors contribute to the authenticity of the complete shot. Then there are other issues such as perspective changes, lighting direction, shadows... it becomes an iterative process sometimes, since all you are supposed to be responsible for is the general feel between the elements so that they seem to be appropriate for their settings, but if care has not been exercised in designing the effect elements in the first place, all you can hand to the next step is the best compromise.

So your actors were shot under flat studio lighting (daylight) with a different camera, (say a 5K EPIC) than the bg element, which is a middle of the night alleyway that has a single (and flashing) practical emergency light offscreen (by a run and gun, handheld H264)? That would be fun. Ka-ching!

jPo

"I always pass on free advice -- its never of any use to me" Oscar Wilde.


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andrew smith
Re: Blue Screen Grading - best practices for balancing blue screen plates.
on Sep 5, 2012 at 11:09:27 pm

Thank you for the response Joseph.

I am just a little confused by this: "So after you have roughed in your plates, either by linking an alpha channel or extracting a matte from the blue/green/whatever foreground and connecting that to the appropriate plate layer, then you are simply grading to achieve what we always do."

I am not sure I understand what you are suggesting for workflow precisely in Resolve..do I have to do a temporary key of the blue background and THEN grade everything to match or is there other methods - regardless can you explain?

Thank you!




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Joseph Owens
Re: Blue Screen Grading - best practices for balancing blue screen plates.
on Sep 6, 2012 at 2:23:27 pm

[andrew smith] "do I have to do a temporary key of the blue background and THEN grade everything to match "

Perhaps you are not aware that Resolve can create a composite preview of the combined greenscreen layers. At that point, you are grading "in context", instead of comparing one plate to the next with stills, etc. You do still have separate control over both the background and foreground, as they are separate elements, but balancing elements within a scene, whether they are qualified by a secondary from within an original shot or the result of a matte inclusion is exactly the same grading task as any other.

This is covered in the manual... about 14 pages are dedicated to this operation. In the Resolve 9 pdf, it starts at about pg 487.

jPo

"I always pass on free advice -- its never of any use to me" Oscar Wilde.


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andrew smith
Re: Blue Screen Grading - best practices for balancing blue screen plates.
on Sep 7, 2012 at 3:40:52 am

I am aware that you can do this in Resolve yes.

I was curious to know if this is the recommended method of grading material of this nature - both for blue/green screen as well as just some other solid background wall for example. How have you typically graded blue screen material to all match? Would love to get some feedback from you and anyone else who has had to deal with his material in Resolve.

I appreciate you pointing out the page in the new manual, I will checkout that section now.
thank you
Andrew




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