what do you need to know to create the original footage for a chroma key shot
These days, we all know the fantastical backgrounds in large blockbuster movies await underwhelming on set. Only with green screen (and major help from visual effects artists and compositors), filmmakers are creating worlds with an unbelievable sense of actuality.
The technique backside green screen actually dates dorsum to the early 1900s. Blue screen was more popular at get-go because it worked better with celluloid motion-picture show. Green screen is more than common and practical now with the rise of digital filmmaking. And you lot, dear filmmaker, can take advantage of its increasing accessibility.
WHAT'S Green SCREEN & HOW DOES IT Piece of work?
Greenish screen is a visual effects (VFX) technique where ii images or video streams are layered—i.east. composited—together. Retrieve about backside-the-scenes clips or bloopers reels from Hollywood movies. It'southward hard to miss the sheer corporeality of green you meet on prepare.
Dark-green screen basically lets you drop in whatever background images you want behind the actors and/or foreground. It'due south used in picture show production (and also in news and weather condition reports) to relatively simply identify the desired background behind the subject/role player/presenter. When a background isn't available—like a fictional, conflicting, historic, futuristic or fifty-fifty just difficult-to-admission location—green screen comes to the rescue!
Subsequently the footage is shot, the compositors take over:
- The new groundwork is composited (i.e. ii images or video streams are layered together) into the shot.
- The chroma key singles out the selected colour (usually the green) and digitally removes it past rendering it transparent. This lets the other image to evidence through.
- When used with more sophisticated 3D techniques, this process tin can add whatsoever new element (smoke, burn down, rain, etc.) to complex moving shots.
AN Important Notation: WHY Dark-green?
Technically, you can use any color background. A vibrant, almost neon green is the standard choice because it'due south strong and usually a distinctly different colour from anything on the field of study (east.g. the player's clothes, eyes, hair, accessories).
But green doesn't piece of work for everything. Yous wouldn't be able to film Kermit the Frog against a dark-green screen—he'd disappear! In this case, y'all'd typically use a blue screen, the "second-in-line" colour.
The fundamental rule is no matching colours! The groundwork has to be a completely unlike colour from the bailiwick. Otherwise, if let's say your player is wearing a bright green tie in front end of a greenish screen, he'll end upwardly with a transparent strip downwardly his chest where the tie is supposed to be!
HOW TO SET UP A GREEN SCREEN SHOOT
- No green or reflective surfaces.
- Avoid dark-green like the plague. Don't have the subject habiliment or concord annihilation light-green or else the areas volition be transparent in one case chroma-keyed.
- Cogitating materials are also a no-no. Shiny objects (e.g. glasses, large jewelry, props, etc.) volition pick up the dark-green from the screen and will also be rendered transparent. Very small jewelry is usually okay though.
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- Have makeup available.
- Actors can look pale and sickly against a green background. You might need some makeup adjustments.
- Allow depth.
- For a full shot of your actor, yous'll need to support the photographic camera to permit the full figure shot plus a good separation betwixt the field of study and the green screen (normally at least six feet to avoid "spill").
- Depending on the lens, you'll typically want 25-thirty feet depth for a full-length shot that doesn't shoot off the edges of the background.
- Use a "coved" greenish screen for best results.
- To testify your player/subject area from caput to toe, the green screen has to continue down the wall and onto the floor under their feet.
- A cove (a curved corner where the wall meets the flooring) will smooth out the transition from wall to flooring. You want to avoid shadows and hard lines that cause slope changes in the green background.
- Lite evenly and softly.
- Low-cal the green screen as smoothly as possible to give an even texture and gradient. The more than even the lighting, the better and easier information technology'll be to dispense the cloth.
- Proceed the green screen itself as clean and smooth as possible to maintain a consistent colour range. If the screen is fabric, make sure in that location aren't whatever wrinkles. If painted, proceed extra paint on hand to touch upwards whatever scuffs and scratches.
- Light separately.
- The green background should be lit separately from the subject to avoid: a) the field of study casting shadows on the groundwork (causing uneven slope) and b) a green hue billowy off the subject, which will crusade bug when removing the groundwork.
- This is also why y'all'll want at to the lowest degree six feet separation between background and subject.
- Go on the camera even so.
- For unproblematic green screen shots, proceed the camera completely static. Lock downwardly the camera and so the subject doesn't await like it'southward vibrating or bouncing against the background when the photographic camera moves fifty-fifty slightly.
- Zooms too look strange. Your subject will await like it'south shrinking or growing in relation to the background.
- You tin employ move command and motion trackers for more sophisticated 3D shots, merely it's a lot more than work for the VFX team.
- Employ Blush Central software that works for you lot.
- Research and consider software based on the shots needed, the editing system, budget, and user feel. Your options for Chroma Fundamental software will essentially depend on the type of shot.
- There's gratis, user-friendly software for simpler shots, only they probably won't exist able to pull off the more sophisticated effects you see in feature films.
And that's pretty much all you demand to know to go started! It might seem complicated, but these tips will help your shoot go smoothly. So go ahead and set your story on an conflicting planet. With time and practice, filming with greenish screen can open up an entirely new, almost unlimited, creative playground.
Whether you're pursuing a VFX career or want to be a 1-human being moving-picture show machine, check out our 3-Month Compositing Certificate program. You lot'll learn and exercise everything covered in this article and so much more.
This short, intensive plan is for anyone (fifty-fifty with absolutely no VFX knowledge!) who wants to hit the ground running as a junior compositor in Vancouver's booming VFX industry.
Source: https://infocusfilmschool.com/filming-green-screen-guide/
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