This masterclass was a lesson on composting, which is the process of combining visual elements from seperate sources into single images, often to create the illusion that all those elements are parts of the same scene. Live-action shooting for compositing is variously called “chroma key”, “blue screen”, “green screen” and other names. Some of the techniques included in compositing are CGI, rotor scoping, 2D/3D mapping, motion tracking, and more. We were to do compositing green screen footage as our lesson.

Things I learned:

Incrementally saving work is better than saving it in the end. Multiple versions lock the project, create time-stamped back-ups, and give the impression of development. A client will feel that more work has been done if they see things like ‘version 1’, ‘version 2′, etc.

VFX is the process of making the impossible or impractical, achievable, and believable. For example, when a scene is of a desert, it would be dangerous, costly, and impractical to actually shoot it in a desert, so the environment is created with green screens.

An asset is a piece of media that can be used in projects. This includes images, textures, videos, animations, logos, and more.

Chroma Keying. Chroma means colour and keying means the selection for removal, so chroma keying is the process of selecting the colour for removal – essentially, green screen. Green and blue are the furthest colours away from skin colour, so they are most commonly used in the film industry. Modern cameras are actually two times more sensitive to green, blue or red than other colours, so that is another reason why green screens are often seen in film production.

There are quite a few things to consider when working with green screens. Shadows can be a problem. It is best to try and avoid a single hard light being shone on the subject, as strong shadows can be created, which make it harder to capture a smooth and even colour. Real light sources can be considered, and are often easier on the actors, giving them a more realistic atmosphere to act in.  Camera layout is also very important; keeping the green screen in shot can be a difficult task, but there cannot be any distractions when shooting the scene. The actors’ costumes need to be thought about as well, considering what is green, what clashes with the screen etc.

 

Do ✔ use a flat, even background. Any colour works as long as it is smooth.

Don’t ✘ wear anything of the same colour as the background.

 

Do ✔ light objects and actors properly to reduce light spill

Don’t ✘ create harsh shadows on the green screen that will make keying harder.

 

We got some footage given to us to practise with and follow along with the demo before attempting something by ourselves. Here is the demo, step by step:

 

1.  Firstly, import all of the assets to the left of the screen. Drag the footage over ‘camera and shapes’ to create a new composition with it as the video layer.
2.  Drag the image(s) underneath the footage as separate layers.
3.  Select the video layer, click effect, keying and then keylight 1.2. This is the green screen keyer.
4.  In effects controls, change ‘final result’ to ‘intermediate result’. This provides better light suppression.
5.  Click on the colour picker and select the green that you feel covers most of the screen. The image that is on a separate layer should now appear underneath.
6.  Change ‘intermediate result’ to ‘combined matte view’  which makes everything monochrome and shows the gradient of the background. The white is what is visible, so if there is any white on the green screen, this should be darkened to black to give a better image.
7.  You can remove any white or grey by going to screen colour, screen matte, and playing around with the settings. For this demo, simply adjusting the contrast was enough to remove the problem.
8.  After this, change back to intermediate result.
9.  Finally, in effect, keying, click on advanced spill suppressor. Then the video is complete.

 

After doing this together as practice, we each got to try it out ourselves. I went to pixbabay and scrolled through their selection of green screen clips and found one of the lying cards which looked really fun. I knew then that my theme would be card games and gambling. Instead of only one, I picked several images. I didn’t want simply a background image, I wanted to have a little showreel of images, the last one being of a woman throwing cards. I thought it’d be really cool if I could get the greenscreen footage to start then, and mimic the effect of her throwing the cards.

I followed my notes from the demo and ran into a few obstacles since I was using more than one image. In the end, the flying cards didn’t start in the last picture. I decided that this would be too boring because you’d be settled on one image and have to wait as the video plays. I thought it was more dynamic and interesting to have the cards flying throughout the showreel, and I really like the result.