FORUMS: list search recent posts

Shooting an old train on Green screen

COW Forums : Adobe After Effects

<< PREVIOUS   •   FAQ   •   VIEW ALL   •   PRINT   •   NEXT >>
eli rezik
Shooting an old train on Green screen
on Jan 11, 2017 at 6:14:13 pm

Hello everyone,

In a couple of weeks I'm going to shoot a short film in an old train cabin. of course we are shooting in a stand still train, and using green screen for the outside.
however before I go any further, I'd like to consult with you about preparing for this shoot.
The director really likes the dirty windows of the train, as seen here.



Now the window already has some ND cover on it, and the dirt does alter the real colors of the outside. Should we clean the windows and add this dirt back in after effects later? or will it be ok to shoot this way.

other than this, it's a night ride and a night shoot, and the director really wants reflections. now I've never dealt with reflections and green screen before. how much of a problem is that? I know it's impossible to fake such reflections in after effects.


Thanks for the answers ☺

Eli

http://www.youtube.com/elireo


Return to posts index

Dave LaRonde
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 6:29:02 pm

You might be successful shooting this as a practical effect, with a mechanism moving various lights against a black backdrop. No After Effects work necessary, and you can see the shot immediately after you get it.

I would recommend running tests, of course......

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


Return to posts index

Walter Soyka
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 8:55:10 pm

[Dave LaRonde] "You might be successful shooting this as a practical effect, with a mechanism moving various lights against a black backdrop. "

Check out how they mixed green screen and practicality for Girl on The Train (last paragraph):
http://www.studiodaily.com/2016/10/studiodaily-dossier-the-girl-on-the-trai...

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive [twitter]   |   RenderBreak [blog]   |   Profile [LinkedIn]


Return to posts index


Simon Ubsdell
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 9:16:35 pm

It's always a good idea to have a really strong sense of the lighting you want even in a green screen situation.

It's never an easy accommodation to pull off but this is a nice example of how you can add greater realism and dynamism to the lighting which is often the biggest problem with green screen.

Simon Ubsdell
tokyo productions
hawaiki


Return to posts index

Simon Ubsdell
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 6:29:22 pm
Last Edited By Simon Ubsdell on Jan 11, 2017 at 6:56:31 pm

It is perfectly possible to pick up nice reflections and dirt with a good keyer from well shot footage.

But the issue that so many people are running up against these days is that they are shooting highly compressed formats and then wondering why they can't get subtle detail into their keys without horrible amounts of noise creeping in and ruining the whole thing. Reflections need very clean source footage to key properly.

So the most important question you need to be asking is how much noise you are going to get off the camera.

Looking at the combined RGB output is not going to give you a good picture because you're not seeing the true horror of what's underneath. Keyers need nice clean signals in all three channels and this is where the compression artefacts really kill you. Make sure to run some camera tests where you analyse each channel for noise. If you see blocky artefacts, your key is dead in the water before you start. If one channel is noticeably noisy, you are entering a world of pain.

Simon Ubsdell
tokyo productions
hawaiki


Return to posts index

Greg Gesch
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 7:00:43 pm

Hi Eli, this may be of some use.

http://www.videocopilot.net/tutorials/advanced_soft_keying/


Return to posts index


Simon Ubsdell
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 7:09:10 pm
Last Edited By Simon Ubsdell on Jan 11, 2017 at 7:11:27 pm

It's a nice tutorial as always from Andrew Kramer, but the important thing to notice about it is that it requires a very, very render-intensive denoise process to be able to handle the reflections in this scene. (And that's just a tiny clip not a whole film.)

And this is for the reasons that I gave in my post above. Compressed footage is always going to create horrendous problems for subtle keying effects like reflections.

Simon Ubsdell
tokyo productions
hawaiki


Return to posts index

eli rezik
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 7:13:45 pm

Thanks for the quick replies everyone

We will be shooting with a mini Alexa - Log C. So Noise shouldn't be much of an issue, or am I wrong?

http://www.youtube.com/elireo


Return to posts index

Dave LaRonde
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 7:16:23 pm

What will the recording codec be? Log C is just a color space. It's not an indicator of how much image information will ultimately be recorded.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


Return to posts index


Dave LaRonde
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 7:14:51 pm

[Simon Ubsdell] "Compressed footage is always going to create horrendous problems for subtle keying effects like reflections."


Amen, Brother!
People these days think, "Oh, it's 4K footage! Our troubles are over!"

If it's highly-compressed 4K, you're going to have the same keying woes people had with DV. Just at a higher resolution.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


Return to posts index

Simon Ubsdell
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 7:21:19 pm

[Dave LaRonde] "People these days think, "Oh, it's 4K footage! Our troubles are over!""

I couldn't agree more.

4K is the work of the devil and the compression issues are simply not understood by the majority of people shooting it.

As a keyer developer myself, I have seen some real horror stories from users who haven't realised what they were getting into until it was too late.

I blame the ridiculous marketing that has completely white-washed this issue.

Simon Ubsdell
tokyo productions
hawaiki


Return to posts index

eli rezik
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 7:30:00 pm

Ok so after checking with the Director of photography it's going to be
Pro-res 444 - 2K - Log C.

http://www.youtube.com/elireo


Return to posts index


Simon Ubsdell
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 7:43:43 pm

I don't know enough about the Alexa Mini to say for sure, but that sounds as though it should give decent enough results if it's identical to its big brothers.

Don't forget that ProRes (even 4444) is a compressed codec so it's not without issues of its own.

I cannot stress too strongly the importance of running tests and looking with an extremely critical eye at the cleanness of each channel.

Also bear in mind that an underexposed green screen is going to be a lot noisier than a well lit one, but your director might be wanting a subdued look which is going to fight with that. There are plenty of complex and not necessarily easily resolved factors you need to take into consideration here.

Simon Ubsdell
tokyo productions
hawaiki


Return to posts index

Richard Herd
Re: Shooting an old train on Green screen
on Jan 12, 2017 at 12:48:35 am

[Simon Ubsdell] "underexposed green screen"

Getting back to the basics. What does underexposed mean?

Let's make it easy. We have 5 stops of latitude: 2, 2.8, 4, 5.6, 8

IMO "underexposed" means everything darker than 2, and overexposed means everything brighter than 8.

Supposing we place the talent at f/4, in a reflection heavy environment, at what f/stop should we light the greenscreen?

Thanks!


Return to posts index

Simon Ubsdell
Re: Shooting an old train on Green screen
on Jan 12, 2017 at 5:21:36 pm

The very authoritative VES Handbook of Visual Effects (pp.111-112) recommends something rather different from what you often read from DOPs and others, which is that you should aim for a half to one stop of underexposure in relation to the foreground.

"A common misconception is that backing brightness should be adjusted to match the level of the foreground illumination. ... To reproduce the full range of transparency, the green screen should be fully - but not over - exposed. In other words, its brightness should match the green component of a well-exposed white object like a white shirt, roughly defined a the whitest white in the foreground that still has detail."

My take on this is that it's complicated ... a lot more complicated than can simply be explained here.

Simon Ubsdell
tokyo productions
hawaiki


Return to posts index


Simon Ubsdell
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 7:38:52 pm

The other thing I would say about this video is that it shows very clearly how unsuited Ae is to even slightly complex compositing situations.

You are far better off working in Nuke or Fusion if you're doing anything except the simplest key.

Getting great looking keys is all about being able to have total control over how the comp fits together, especially in terms of splitting off processes to deal with particular issues of particular areas of the frame. All of this is still doable in Ae, but it's a real pain and seriously clunky. And the clunkiness means a lot of the time you are not going to push for perfection because it's just too much work.

Simon Ubsdell
tokyo productions
hawaiki


Return to posts index

eli rezik
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 8:05:48 pm

Well I've been working with after effects for the past 7 years and never really used fusion or nuke.
How hard of a transition is it?

http://www.youtube.com/elireo


Return to posts index

Simon Ubsdell
Re: Shooting an old train on Green screen
on Jan 11, 2017 at 9:02:37 pm

I would say that the benefits of using Fusion (which you can get for free, unlike Nuke) would outweigh any learning curve for this kind of job.

But then I started on Fusion at a time when Ae barely existed, so I guess I am not the best person to ask.

If you are staying in Ae, I hope you won't mind my recommending that you look at Hawaiki Keyer (which I have developed with my brilliant partner, Rob Mackintosh), which in addition to creating great-looking keys with the minimum of guesswork, brings you a whole range of advanced compositing features that are not available in any other keyer at any level, and which will have another feature-rich update fairly soon. There is a free trial version so you can experiment and see whether it is useful to you.

Simon Ubsdell
tokyo productions
hawaiki


Return to posts index

Blaise Douros
Re: Shooting an old train on Green screen
on Jan 13, 2017 at 6:54:46 pm

You might also try shooting with a full blackout outside of the window, and using a simple blending mode to overlay your "outside" footage. That would preserve your dirt and reflections.

Or, go old-school (which is back in fashion now) and shoot background plates for your exterior, and fire that footage onto a projection screen outside. You could even run the same clip a half second ahead on a second projector shooting in the window, out of focus, to simulate the effects of that lighting on the actor.

Like Oblivion, on a smaller scale. And you don't need the huge screens, because you're only seeing out of a single window.







Spend a bit more on set to get it practically, save a headache in post.

It would be worth shooting tests, if you can swing it. Quick and dirty, same interior lighting setup, grab two or three shots per setup, and change the exterior setup between takes. Then you can walk in to the shooting day confident.


Return to posts index

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