FORUMS: list search recent posts

VFX shots. Grade before or after?

COW Forums : DaVinci Resolve

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
MichaelMaier
VFX shots. Grade before or after?
on Mar 9, 2013 at 1:08:07 pm

I'm wondering what's the best procedure with VFX shots. If you should grade the plates and then send to VFX or grade after the VFX shots are finished?

I would think grading the finished VFX shot would be better. That way you grade it as a whole. If you grade it before, it would need to be graded in the compositing software to make the added stuff match. Or send it back to regrade in Resolve, which will add another unnecessary compression step, unless it's uncompressed. Not to mention that it would be harder to grade now since you would need to isolate the VFX stuff. Much easier to do that in the compositing software where they are already different plates. But it would be up to the VFX guy to do your grading then.

Like let's say you have a shot where gun muzzle fire, blood hits, dust etc must be added to the shot. If graded after, all that will automatically match the grade of the original shot. If you grade before, who knows how it will look after it's put on. Specially if you are going for a look.

What do you think?


P.S. For noise reduction I normally do after grading. Unless the shot need to be saved and is nearly unusable without NR.


Return to posts index

Clark Bierbaum
Re: VFX shots. Grade before or after?
on Mar 9, 2013 at 3:10:37 pm

Depends! Always a safe answer!

If its only one or two elements in a shot, I like to get the matte and fill and grade the separate elements in context. This works well if you have good integration with the graphics folks, color space, timebase(fps) and TC all need to be right for it to work.

Love the add matte feature of Resolve!

Clark Bierbaum
Color Grading / Post Consultant
GarnetColor.com
Charlotte, NC


Return to posts index

MichaelMaier
Re: VFX shots. Grade before or after?
on Mar 9, 2013 at 3:35:34 pm

Thanks.

But it also means to depend more on the VFX people, which always complicates things. Do you see any problems with just grading after? Grading the finished shots that is.
Besides, I'm not talking shots with only one or two elements.



Return to posts index


Chris Kenny
Re: VFX shots. Grade before or after?
on Mar 9, 2013 at 4:00:10 pm

[MichaelMaier] "But it also means to depend more on the VFX people, which always complicates things. Do you see any problems with just grading after? Grading the finished shots that is.
Besides, I'm not talking shots with only one or two elements."


There are two downsides to grading afterwards. One is that depending on where you take the grade, there's a possibility that artifacts that weren't visible in the ungraded shot — like imperfectly matched black levels for different elements, edges of rotoscoped objects, etc. — may become visible.

The other is that if you're working with raw footage (like R3D or ARRIRAW), whatever settings were used to decode that footage to do the VFX work will be baked into the VFX shot. So, for instance, if you've decided to change the raw white balance of a bunch of shots in a scene, but there's one VFX shot containing elements that were 'developed' with the in-camera white balance, you might have some tricky matching issues.

--
Digital Workflow/Colorist, Nice Dissolve.

You should follow me on Twitter here. Or read our blog.


Return to posts index

MichaelMaier
Re: VFX shots. Grade before or after?
on Mar 9, 2013 at 4:29:20 pm

[Chris Kenny] "There are two downsides to grading afterwards. One is that depending on where you take the grade, there's a possibility that artifacts that weren't visible in the ungraded shot — like imperfectly matched black levels for different elements, edges of rotoscoped objects, etc. — may become visible."


In that case, just send it back to the VFX guy to correct it? :)
Unless I misunderstood you?

[Chris Kenny] "The other is that if you're working with raw footage (like R3D or ARRIRAW), whatever settings were used to decode that footage to do the VFX work will be baked into the VFX shot. So, for instance, if you've decided to change the raw white balance of a bunch of shots in a scene, but there's one VFX shot containing elements that were 'developed' with the in-camera white balance, you might have some tricky matching issues."

I will be working with DNxHD files for this specific project.




Return to posts index

Chris Kenny
Re: VFX shots. Grade before or after?
on Mar 9, 2013 at 5:09:46 pm

[MichaelMaier] "In that case, just send it back to the VFX guy to correct it? :)"

Sure, time and budget permitting.

--
Digital Workflow/Colorist, Nice Dissolve.

You should follow me on Twitter here. Or read our blog.


Return to posts index


MichaelMaier
Re: VFX shots. Grade before or after?
on Mar 9, 2013 at 5:25:19 pm

Yeah, I know. Budget. :(

But for the clips that become problematic, maybe I could ask the mattes to the VFX people to try to isolate the problem? Unless most of the clips would become problematic.

It's starting to look like you either trust the compositor to match the added elements to your graded look or you have a lot more work. Dang!



Return to posts index

Clark Bierbaum
Re: VFX shots. Grade before or after?
on Mar 9, 2013 at 4:02:55 pm

Yes, the experience of the graphics person(s) / companies vary widely! The most important thing I've found is to give them your specs about color space, time base, time code matching and shot naming.

The color space and matching gamma in and out of the efx program is critical, would suggest you test and document the steps and traps.

EFX is hard to do (see) on log footage but if the file they return has been linearized it may be hard to match with the camera original footage. I've had LOG background plates with linear foreground elements, FUN!

Suggest (demand?) to test a clip through the entire process before the project starts, and be prepared to explain why this is so important. Email or other documentation is a great CYA (Cover your A$$) method.

It's always nice to hear from the client they are using someone who gets all of this. I spent many hours dealing with elements from people who don't and it really is frustrating, especially when working for a fixed price!

Clark Bierbaum
Color Grading / Post Consultant
GarnetColor.com
Charlotte, NC


Return to posts index

MichaelMaier
Re: VFX shots. Grade before or after?
on Mar 9, 2013 at 4:33:12 pm

[Clark Bierbaum] "EFX is hard to do (see) on log footage but if the file they return has been linearized it may be hard to match with the camera original footage. I've had LOG background plates with linear foreground elements, FUN!"

I will be working with DNxHD for this specific project.

[Clark Bierbaum] "It's always nice to hear from the client they are using someone who gets all of this. I spent many hours dealing with elements from people who don't and it really is frustrating, especially when working for a fixed price!"

I can definitely relate to that. :(



Return to posts index


jake blackstone
Re: VFX shots. Grade before or after?
on Mar 10, 2013 at 6:23:38 am

"If you grade it before, it would need to be graded in the compositing software to make the added stuff match."
That's weird statement. Are you saying, that VFX guys, when they composite, they don't match the new material to the plate?:-)
And, yes, it is much better to pre grade the material properly and not leave this step to VFX guys, if you don't want to get back horribly graded material with weird color metadata choices and baked-in color. Any VFX artist worth his salt knows how to properly linearize supplied LOG material and then return composited shot back with a proper Cineon curve applied. In Nuke it's super simple. Using supplied mattes is great, unless you have hundreds of them and then you have to manually match them with the material. Once Resolve starts supporting material with alpha channel mattes, then it's different story. Right now I'd hope, that VFX artists would match composted material with pre-graded plates and then just grade it all together.


Return to posts index

MichaelMaier
Re: VFX shots. Grade before or after?
on Mar 10, 2013 at 12:33:21 pm

I was not talking about pre-grading. I was talking about fully grading it, giving it a look and then sending the plate to them. I know VFX artists can match plate colors. But when you already have a stylized look to the plate it makes it more difficult.



Return to posts index

Dan Moran
Re: VFX shots. Grade before or after?
on Mar 10, 2013 at 2:46:50 pm

We grade all the plates first then the VFX artists to comp into it. Sometimes just a tech grade to balance things out and Log C -> rec709 conversion and sometimes we do the look also.

If they can't match then their obviously not a very good VFX artist! Once all the comping is finished then we'll take it back into the grade for a final grade.

Works well in commercials

--

Dan Moran
Colourist
Smoke & Mirrors: London
http://www.danmorancolor.com/blog


Return to posts index


Juan Salvo
Re: VFX shots. Grade before or after?
on Mar 10, 2013 at 6:55:28 pm

This to me is exactly where ACES has so much potential.

Colorist | Online Editor | Post Super | VFX Artist | BD Author

http://JuanSalvo.com


Return to posts index

jake blackstone
Re: VFX shots. Grade before or after?
on Mar 10, 2013 at 10:03:42 pm

I actually prefer the FilmLight's approach with the Baselight Editions plugins, including one for Nuke and upcoming Flame.


Return to posts index

Juan Salvo
Re: VFX shots. Grade before or after?
on Mar 11, 2013 at 6:50:10 am

It's interesting. But then you're stuck in a proprietary pipeline. The whole point of aces is its standardization, it can work on any platform. I'll take a versatile open pipeline any day, you can just as easily use aces with a resolve as you can with baselight, film master, nuke, ae, etc, etc.

That to me is the future, as much flexibility and interoperability as possible. Closed platforms, and pipelines aren't cutting it anymore.

Colorist | Online Editor | Post Super | VFX Artist | BD Author

http://JuanSalvo.com


Return to posts index


jake blackstone
Re: VFX shots. Grade before or after?
on Mar 11, 2013 at 8:30:22 am

Why? Is FCP XML proprietary? Of coarse not. Premiere writes it as well. FilmLight utilizes the same mechanism by handing off all grades and metadata by using XML between various plugins and standalone Baselight. The same way Premiere utilizes FCP XML other manufacturers can do the same with Baselight XML. There is nothing proprietary in FilmLight's approach.
On the other hand, Resolve is completely closed off to any third party plug in developers. And the support of the third party panel manufacturers is abysmal. It sounds pretty bad this way, if I say it, doesn't it?


Return to posts index

Joseph Owens
Re: VFX shots. Grade before or after?
on Mar 11, 2013 at 6:18:02 pm

[jake blackstone] "Why? Is FCP XML proprietary? Of coarse not."

Not what Juan is talking about. ACES is about colorspace/overall color management; all sources are characterized so that they behave or appear to have the same colorometric behaviour. There is some discussion about it being the unifying factor for exactly this grade/VFX trade-workflow. And there is probably enough confusion, for example, about Redgamma and how it relates to 709 gamma or DCI space, which is the danger in the "freelance"/proprietary approach.

BTW, Resolve does support alpha channels now, and I do prefer to treat the fg/bg plate work as layered composites in Resolve. Even if it is a "baked" final, as long as there is a travelling matte or alpha channel, I'm good. It is difficult for most FX people to be able to grade in context, usually because they don't have judgement monitors to work with, and the big limitation -- don't have the benefit of seeing an entire scene - they usually only have the clip with handles - so have no idea where this came from or where its going. Producers may even change their minds mid-post and change the time of day. "Oh, I know, this would work way better if it was golden hour".... or.... "yeah, we ran out of time on set and had to shoot this noon scene at dusk. You can fix that, right?" Sure.

Its also much nicer to be able to re-grade the composite further downstream for overall vignettes, etc. which also tends to support the notion that colorists are edging towards becoming part of the overall FX discipline.

jPo

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


Return to posts index

jake blackstone
Re: VFX shots. Grade before or after?
on Mar 11, 2013 at 6:49:47 pm

No, I think you're confused between XML, ACES and metadata. FilmLight approach doesn't exclude the use of ACES. It works in CONJUNCTION with ACES. Their workflow allows pre-grade of the plate without rendering the material and maintaining metadata rich environment, while using ACES. Then composited EXR shots from NUKE can be open and graded in context with layers, previous grades and metadata still intact.


Return to posts index

MichaelMaier
Re: VFX shots. Grade before or after?
on Mar 11, 2013 at 7:01:13 pm

[Joseph Owens] "It is difficult for most FX people to be able to grade in context, usually because they don't have judgement monitors to work with, and the big limitation -- don't have the benefit of seeing an entire scene - they usually only have the clip with handles - so have no idea where this came from or where its going."

So are you saying that you would rather grade VFX shots after the VFX are done then?



Return to posts index

Joseph Owens
Re: VFX shots. Grade before or after?
on Mar 11, 2013 at 10:32:03 pm

I will grade wherever in the workflow that it makes sense.

If the VFX have not been done yet or maybe we don't even know this is going to be an FX shot, or maybe because I'm the first stop after picture lock, I will treat images prior to handoff -- trying not to compromise any greenscreens so that we're not hooping the matte. Conversely, as long as the fg/bg plates can be separated, and we've agreed to exchange ProRes4444 with an alphamatte, if elements need to be treated differently (grading in contex), as if the completed composite were an original scene -- that's fine, too. Often, if I happen to also be doing the VFX work and I know where the scene is going, I'll do both -- pre-bias the source elements so that whatever is happening to it later its already in its appropriate dramatic role -- its a bit like an actor staying in-character and in-costume between takes. Or maybe I can simply stick the finished composite back in the Final Cut timeline and it doesn't go back to grade. I'll do this with cleanups as a rule -- if all you're doing is a logo or wire removal, the grade is the grade, and if there is something about the shot that needs another tweak ("Can you take out that other truck too?"), then its not a double round trip, just re-do the composite, not *plus* the correction, just to get it back to where you wanted it in the first place. That can backfire, of course, if you compromise an area that you need to borrow for a clean-plate.

So, there is no "better", "set", approach.

You can really help the VFX along if you can set the look of a scene -- for example, if FX is placing a model building or other object into a landscape-- big consequences for how the model is lit, according to time of day. If the modeling department can get that right, we're good to go, but otherwise, if the producer/ post supervisor wants to do some more shading, that needs to be planned (as above), and it is a huge advantage to see that layered final.

And believe me when I say that I do count generations; that dates back to doing multiple effect passes on Super HIgh Band AVR-3 quad videotape, in NTSC, composite baseband. (That means if you haven't figured out how to do it in 3 generations, you need to start over again, because what's left after that is mud.)

jPo

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


Return to posts index

MichaelMaier
Re: VFX shots. Grade before or after?
on Mar 11, 2013 at 10:42:26 pm

Thanks. It makes a lot of sense.

[Joseph Owens] "That means if you haven't figured out how to do it in 3 generations, you need to start over again, because what's left after that is mud."

Ha! Are you talking about the Super HIgh Band AVR-3 quad videotape days or today? :)



Return to posts index

Joseph Owens
Re: VFX shots. Grade before or after?
on Mar 12, 2013 at 4:20:07 pm

[MichaelMaier] "Are you talking about the Super HIgh Band AVR-3 quad videotape days"

1980-1986. But the same limitations still hold true with some of today's lossy DV codecs, which tend to fall apart even faster. ProRes and DNxHD have made enormous strides, though, and 8-10 generations, which aren't really re-compressions, really do hold up well. I really do disagree with attempting to flip back and forth, though, between RGB and Y'CbCr with so-called "Uncompressed" codecs and TIFF/DPX sequential files. Its not penalty-free, considering the re-matrixing and 4:2:2 processing that necessarily have to happen.

jPo

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


Return to posts index

MichaelMaier
Re: VFX shots. Grade before or after?
on Mar 13, 2013 at 2:54:47 am

[Joseph Owens] "ProRes and DNxHD have made enormous strides, though, and 8-10 generations, which aren't really re-compressions, really do hold up well."

What would you consider really re-compressions or not?


[Joseph Owens] "I really do disagree with attempting to flip back and forth, though, between RGB and Y'CbCr with so-called "Uncompressed" codecs and TIFF/DPX sequential files. Its not penalty-free, considering the re-matrixing and 4:2:2 processing that necessarily have to happen."

Totally agree here. I think once you go RGB(DPX) you should stay there.



Return to posts index

Joseph Owens
Re: VFX shots. Grade before or after?
on Mar 13, 2013 at 4:57:43 pm

Its just my internal guideline, and pretty sure that there will be general disagreement.

A recompression for me is a transcode from one codec to another -- even within the same family, where a color-encoding, bit rate, or intra-framing recalculation occurs. To a certain extent, not even the render from a grade application, unless you are changing codec, really qualifies as a full recompression, more like a fractional "generation". All you are really doing is re-assigning the HSL or RGB values of single pixels, and this doesn't really change its relationship to its surrounding value fields (slots in the pixel array) at least in a lossless codec. Things do change, however, when you start merging and blending external picture elements -- blurs, sharpening, mattes, noise, grain... and again if you start geometric manipulation. That's a different set of rules.

I don't necessarily count an export from an edited timeline -- for example, all-ProRes-422 clips on a ProRes-422 timeline to create a single ProRes-422 Quicktime to be a full recompression. For me, it is fundamentally a simple re-ordering of the frames. However, there are codecs that exhibit losses quickly because they recalculate values based on long-GOP i-b-p economics, or chroma subsampling. Non-square resolutions also raise more than the usual amount of suspicion as to whether you are getting back exactly what you put in.

When you simply copy a digital file from one directory to another... that's obviously not a compression generation. If you were to change a few of the pixel values inside a frame... but you don't change the codec, that's not really a recompression, either. If you pull a subclip or merge clips, unless the codec depends on the field sequence order for its bit reduction scheme, that's all thats going to change, not the content or values of the intra frames themselves.

Thats my model, anyway.

Love to hear other opinions.

jPo

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


Return to posts index

Paul Abrahams
Re: VFX shots. Grade before or after?
on Mar 21, 2015 at 5:46:40 am

In a completely non pro situation, which is mine and my partners, we both do the shoot, one directs the other is on camera. My work station is a current imac running Davinci which handles RAW DNG's, I send him the proxies to edit in Adobe on Windows. He sends me the XML I do the grade then I send him the final grade. He then replaces the proxies on the timeline with the Graded files and adds VFX and finishes.

So a basic edit seems to work best as Adobe and Davinci deal with complex transitions differently.

Transitions, stabilisation and VFX seem to be best done after the grade and before the final render.

Hopefully this helps any others in a similar situ, or gives me exposure to be shown a better way which I'm always willing to learn.


Return to posts index

Mike Most
Re: VFX shots. Grade before or after?
on Apr 14, 2015 at 3:42:59 am

>>There is nothing proprietary in FilmLight's approach...

Well, no, not if you're referring to the use of standard XML tags. But the approach is completely proprietary in the sense that the file cannot be properly interpreted and the values properly applied without the use of a Baselight or a Filmlight Baselight Editions plugin.

I think what's being overlooked in this discussion is that the use of ACES virtually ensures that the data being presented to the VFX artist is already in scene referred, linear light space. That is usually preferred in compositing because it behaves in a similar way to real world physics, modeling the properties of "real" light. It also operates in a floating point space, ensuring that no clipping takes place through the various compositing operations. ACES is by design very VFX friendly.


Return to posts index

Markus Manninen
Re: VFX shots. Grade before or after?
on Apr 13, 2015 at 8:03:00 pm

I agree. As a VFX Artist/Supervisor and once in a while Colorist, I find the tech grade to be very helpful. If the timeline allows for showing also what the final grade will look like, great. I often find that not to be the case.

It doesn't mean that VFX Artists shouldn't check their work. However. There's so much we can do in Grading that is non-physical, which would mean a lot of additional work to try to match with very different tools.

_____________________
markus manninen


Return to posts index

Simon Blackledge
Re: VFX shots. Grade before or after?
on Apr 14, 2015 at 10:02:22 am

Before. Pretty much 95%



Return to posts index

Aurie Anden
Re: VFX shots. Grade before or after?
on Apr 15, 2015 at 1:42:27 pm

We work mostly with commercials and this is how we do it too. We do a tech grade first where all shots are nicely balanced. This will be a "safe" grade that leans towards the final look already.

After all vfx work is done, we do a final grade. Step one is to make sure everything blends seamlessly. We use external mattes. After everything looks good and "correct", we have more freedom to play with the look and take it whatever direction the director wants to go.


Return to posts index

Simon Blackledge
Re: VFX shots. Grade before or after?
on Apr 15, 2015 at 4:21:14 pm

But don't you need as much latitude in the plates as you can get ?

A tech grade will goto Rec709 plus its a recompress - unless your going log out with a LUT ?

So you'll be comping on possibly Log-c > Rec709 > Lin > :-/



Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]