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Questions on setting up a greenscreen around a house

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Charlie Knott
Questions on setting up a greenscreen around a house
on Jan 8, 2017 at 3:37:31 am

I am currently in pre-production on a short film of mine that introduces a wide variety of technical approaches, all of which I am willing to test out to see what is achievable.

My story is reflective of what visuals and therefore what technical aspects are involved, so I’ll get straight to what I’m set on doing. The order in which I have written the steps below is what I have found to be good for this project, but I am very open to anyone’s feedback and alterations to them -

- I am filming both interior and exterior (the ext. shots take place on a covered front porch) shots of moving actors, with the hopes that I can set up a greenscreen on set that will allow me to key out the background (i.e., the space outside the window and beyond the porch) in post.
- Using those same angles from the initial shoot of the house and my actors, I am going to film from a dock/pier at the ocean’s horizon line, matched up exactly to the house shots.
- Once I have both the background plate and the int./ext. shots with my actors, I plan on filming a small, 3D printed model house on a plinth floating atop a shallow tank of water, in front of an evenly-lit greesncreen. This is so that I can composite the model house onto the ocean shots with the meniscus of the water from the shallow tank mimicking the ocean waves, thus blending the horizon/depth.

My questions are as follows -

- What material, or combinations of layered materials should I use for the greenscreen house shots? I have tested putting green paper in front of a window from the outside, but the green color is backlit and I see the pulp of the paper backlit as well - this has resulted in a noisy key. I have read some forum posts on other sites suggesting that the greenscreen be moved a few feet from the window, but I don’t have that flexibility due to the way my house is built, and because of the fact that some scenes take place in rooms on the second floor.

- What lighting should I use to make sure that both the key is clean and the scene feels natural, even before I composite in the ocean footage?

What lights should I use on this? I have access to ARRI, KinoFlo and Felloni lightkits with any additional softboxes and duvetyne I might need.

- What keying software should I use? I have access to KeyLight in AE CC 2016, but I have heard that DaVinci Resolve’s keyer is good.

- What camera settings should I use? I am filming with a C100, and I have read to underexpose the greenscreen and/or overexpose the actor’s faces/figures, but I'm not exactly sure on this method.

Any feedback would be amazing. Seeing as I’m filming in summer 2017, I have a few months to do tests and figure this out. Your suggestions are greatly appreciated.

-Charlie Knott

Student Filmmaker at MICA
https://vimeo.com/charlieknott


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Chris Wright
Re: Questions on setting up a greenscreen around a house
on Jan 8, 2017 at 6:41:07 pm
Last Edited By Chris Wright on Jan 8, 2017 at 6:43:09 pm

light the greenscreen and see if your vectorscope target is dead in line 60% to green box. There should be no deviation along this line. If there is, you don't have even lighting. Also, your green ire should be lower than you think, exposing green at its native luminance, 49 ire luma, 55 ire chroma.

soft, even light within 0.2 f-stops across screen with lightmeter
keylight is ok, primatte is better
film with 444 10 bit, if not, then 422 10bit, then 4:2:0(hard to key), don't key with transcoded footage. always key from RAW
light actor separately from screen 8-10 ft away, skin at native iso sensor ire white level/60 ire or 1.5- 2 stops more than screen.
http://www.xdcam-user.com/2013/12/cine-ei-mode-when-recording-s-log23-and-r...
if slog3 doesn't have 10 bit, or you don't have RAW, shoot prolost settings instead.
https://prolost.com/blog/2012/4/10/prolost-flat.html

lighting greenscreen video with a vectorscope and waveform monitor






what clothes to not wear
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uac...

setting up greenscreen
http://tubularinsights.com/7-tips-set-up-professional-green-screen/
https://www.videomaker.com/videonews/2013/11/5-green-screen-tips-to-make-yo...
http://www.pinnaclestudiopro.com/green-screen-tips/


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Mark Suszko
Re: Questions on setting up a greenscreen around a house
on Jan 9, 2017 at 3:46:33 pm

Sounds complicated and interesting - my favorite combo.

Not sure if you mean you're going to put the life-size people into a composite on the tiny house model, or if you mean to see the tiny house "floating" at a distance from the full-size house, seen thru windows in the interior and from the porch... kind of as if everything got flooded except for these two homes?

Instead of paper behind the glass, consider applying matte finish green or blue vinyl or painter tape directly to the front surface of the glass on the inside of the rooms. Stick on a sheet and trim with number ten hobby blade Xacto hobby knives. The vinyl peels off clean afterwards.

I'd suggest blue over green for the windows because any spill /reflection situation using blue screen will look more like ambient daylight leakage, and not be as noticeable, where spilled green is unmistakable. once the glass is taped or vinyled over, it may make sense to add a few small tracking markers to help motion-track mattes inside and out. Though markers may not always be needed since windows are regularly shaped rectangles with easy to see corners to anchor on.


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Todd Terry
Re: Questions on setting up a greenscreen around a house
on Jan 9, 2017 at 4:31:49 pm

I was going to suggest green or blue vinyl, too, Mark beat me to the punch. It's going to give you a nice even look, unlike the uneven mottled look of the paper that you tried... and (assuming this is shot during the day) natural exterior lighting will give you backlighting for the vinyl, and you likely won't have to light it at all.

Where to get such a thing? Go to a sign shop, a place that does vinyl signs and banners. They will have huge rolls of it.

You don't need to ad tracking spikes... as Mark pointed out you'll probably have plenty of tracking points on square windows. PLUS, they wouldn't be right anyway... tracking markers on such a thing would only be truly useful if there were where they would be in real life... off in the distance... not so much when the keying material is applied right to the windows.

Ok, warning, here I'm going off on a tangent......

As for the floating of the tiny model in a tank of water... I hate to be one of THOSE guys that shoots down someone's idea... BUT I'll just say I don't see that working very well (and I'd hate for you to waste a lot of time/money/energy/resources on something that ends up being unworkable). You say the goal is "mimicking the ocean waves, thus blending the horizon/depth." Well, that's going to be a tough order, in that water in a tank is just never ever going to mimic ocean waves. For one, you have a speed issue. As you (hopefully) know, when shooting moving miniatures (or miniatures in moving environments) you need to shoot slow mo in relation to how big your model is.

The formula for figuring out that is by multiplying the frame rate times the square root of the miniature ratio.

What the hell does that mean? Ok, lets say you would normally be shooting 24fps, or working in a 24p project. Then the frame rate is 24. Ok, now lets say you are shooting a 1/50th scale, which might be appropriate for something big like a house (giving, say a two-foot model). Then you would multiply 24 times the square root of 50 (for ease we will round that to 7) to get your frame rate... ergo

24 x 7 = 168

Therefore, when normally shooting 24fps, if shooting a 1/50th scale model you would overcrank to 168fps to get natural looking motion.

Then again, you said "smaller 3D printed model" so maybe you are thinking of something even smaller, maybe 6 inches across. If you had a real-life 100ft house, that would be a 1/200th scale model. Ergo...

24 x 14 (the square root of 200) = 336fps

In that case, shooting 336fps (or something in that neighborhood) would give you natural motion on a 1/200th scale model. BUT... you're never going to get water in a tank to mimic the look/action/waves of the ocean... water just doesn't behave that way. Even if you dyed the water (which you would have to do so you don't see through it), I just can believe you'd get anything realistic looking. And even if it did, you can't shoot that with your C100, you'll need a different camera for that shot that can shoot at a much higher frame rate than the C100 can.

Ok, I won't be any more of a party pooper on that. If you want to do it, try it... and let us see the results.

As for "What lights should I use on this?"... well, it's hard to say. You sound like you have good access to a lot of decent instruments, so you should be in good shape. I can't really recommend particular instruments or setups because we don't know anything about this project, what the story is, the look, feel, mood, or anything. A romantic comedy set in the daytime is going to have a very different lighting plot than a horror story set at dusk... and everything in between.

Good luck!

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Mark Suszko
Re: Questions on setting up a greenscreen around a house
on Jan 9, 2017 at 4:39:44 pm

There are several CGI-based solutions for making the "ocean". And the 3-d printed model may be cute, but can't have the flexibility in resolution of a CGI version. If you have enough scans of a house to model it for a printer, you already have what you need to model it in Alias, Lightwave, etc. and that's where I'd point your project. To keep on schedule, hire out the CGI parts to someone who is already fluent in that stuff.


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Charlie Knott
Re: Questions on setting up a greenscreen around a house
on Jan 10, 2017 at 1:34:32 am

Thanks Mark,

I'm really interested in your vinyl idea. And as for the tracking markers, I think I'm going to use the corners of the windows as you had suggested.

I do have a question though -

- For the porch scene, what would you suggest I do? It's not a big front porch, but I still don't want to wrap the entire outside of my porch in blue. I was planning on tightening the shots for those scenes and more often then not composing the shot to the front of the house, but I was just wondering as to what you might do.

And yes, I am scaling the people down into the model house, but for only the wide shots of the house at a distance. For the main porch shots I am doing an on-set bluescreen shoot. And as for the indoor shots I plan on now using the vinyl for the windows. The point of this film thematically is that a small family idlely sails their boathouse across the Atlantic ocean, all of them wanting to go different places.

-Charlie

Student Filmmaker at MICA
https://vimeo.com/charlieknott


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Charlie Knott
Re: Questions on setting up a greenscreen around a house
on Jan 10, 2017 at 1:24:41 am

Thanks Chris,

Both the tutorials and the camera specs you noted have given me a good sense of lighting my greenscreen and looking at the waveform monitor for colors that could interfere with the key. Also the costume decision seems wise.

However I am going to go with the color blue as others have noted here on this discussion - it seems to give a more ambient approach as to the type of light and atmosphere (background) I want to simulate through the windows.

-Charlie

Student Filmmaker at MICA
https://vimeo.com/charlieknott


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