How to make a Green screen and keying in AE

Introduction

If you already have a green screen and want to go straight to the AE tutorial click here.

In this tutorial you will learn about different types of green screens you could use, setting up lighting and how to key in AE or other keying software.

Why Green? Green screen is a newer concept, whereas bluescreen is a old concept going back to when they filmed the original star wars. Green screen is easier for keying a person, because there isn’t much green in a person. In some circumstances blue is better, but we will be using green. You can use these same techniques for blue.

What you will need (all discussed below):

Green screen
Lighting
Software
Camera
Tripod

Types of Green screen you can make

Purpose made:

Purpose made muslin and plastic green screens are available online. They are going to be the best green for keying but are quite expensive. Below are other options you can use which are cheaper!You can by purpose made green or blue paint for keying, but it is quite expensive.

Paint:

To find the correct colour I bought three sample greens for £1 each from the dulux website. I then painted a small block of wood with the three and chose the colour that I thought would be the best for keying. I thought Green Parrot 1 was the best suited for green screen. I chose Egg Shell as this is matte and not shiny like the other option. I bought the Dulux paint from B&Q but you could buy it form a hardware store which was about £8 for a litre, which was enough to cover the piece of wood I had.

A shiny surface would reflect the lights and would effects the keying. You can paint on to any flat surface, which isn’t textured. A textured surface creates small shadows and won’t key as well. For example you could paint on to a wall, cardboard or wood.

Painting on a wall

If you have a wall that you don’t mind painting creates a very good green screen.

Painting on wood

You can use MDF wood which was about £5 at B&Q. It was 2m by 1m and 12mm thickness. Wood is good for using as a floor green screen as it strong and won’t squash if you want to stand on it.

Painting cardboard

I found an old big box, flattened it and painted my paint on that. As you can see for the image it rips quite easily but is more portable than wood.

Felt

Felt is a good fabric for green screen because it doesn’t crease that much. I bought my felt from John Lewis, department store, but you could buy it from a fabric store or online. It is quite expensive about thought, about £7 per meter. You might want to sew to make up the width.

Green screen comparison chart:

Lighting

If you are indoors, to get the best result is to close all the curtains and make sure there is as little external light as possible. If shooting outside if possible have the sun behind the green screen, this means your actor is in the light and no shadows are on the green screen.

When lighting your set, the type of lighting you want is soft light instead of hard lighting on your subject and green screen. Soft lighting creates less of a shadow on the green screen. To create soft light you have to cast light indirectly at the green screen. It is best to use white paper, foam boards or light coloured walls to bounce the light off. As for lights you just need three or four household lights. I bought three from Ikea, they were seven pounds each. I chose then because they came with poles to change the height of them, so you can have a variation of high and low lighting.

Setting up the camera

Its best to have the camera on a tripod, to keep it stable If you have a wide angle lense use it when shooting on a green screen or if not tilt the camera 90 degrees, so it is on its side. This way its more suited to fitting a person from head to foot.

Keying in AE

Below is a video of how to key green screen in Adobe After Effects. It uses a plugin called Keylight 1.2, it is by far the best best plugin for keying with so many options and features. It comes free with CS3 professional and CS4 professional.

Other software that supports keying:
FXHome CompositeLab Pro £89
Final Cut Pro £799
Sony Vegas

Get Adobe Flash Player to view this tutorial or go to effectportal youtube channel.

Submit your green screen videos and comment below!

If you have CS3 or previous click here to see differences to CS4.

More

Techniques when using a green screen:

• Make sure your actor on the green screen isn’t wearing any green, or that will be keyed aswell!
• Try and make as least shadows as possible on the screen.
• Take off any glasses because they are difficult to key.

Improvements you could make:

• Have a go at the CG Stage tutorial which uses the green screen technique to composite a person on to a CG stage
• Camera move with background aswell
• Add another duplicate person in scene/shot using compositing software

If you have a green screen or just made one send us a picture of it or the results you have got from it and I will put it here to show people other ideas.

Downloads

Green screen AE Project: (11.4KB Adobe CS4- not tested on CS3 or previous)
Zip file of raw green screen movie (.mov) 46.1MB

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