Notes on the History of Compositing

Compositing is when various images are used to create an illusion that the elements are a part of the same scene.
Un Homme De Tetes (The four troublesome heads)

• Melies 1898 film used a double exposure technique to create the composite shot. 
• Parts of the exposure where matte paint is used (black).
• Melies is a pioneer of visual effects.

The Great Train Robbery 

• Edwin S. Porter created this film in 1903 using matte painting technique that Melies used.
• Porter used double exposure.

Matte Paintings

• New techniques for augmenting sets were developed in the 20th century.
• The 'Glass shot' was developed by Norman Dawn, it was a plate of glass he started on.
• The problem with this technique was that the paintings needed to be ready on set but Norman Dawn got round this by re-exposing. 
• The technique has been used since the early 19th century. 

The Glass shot 'Soldier Jack'

• Cheaper
• You have limited movement of the camera. 

Black Screen

• Frank Williams patented the 'Black Matting' process in 1918.
• The process used a black background and exposure.

'Sunrise: A song of two humans' (1927)

• Ground breaking when it was first shown to the world. 

Blue Screen

• A major issue of the black screen process was that shadows were lost.
• The Dunning process used coloured lights to identify subjects (yellow)  and background (blue) enabling a clean separation. 
• It can only be used with black and white films.
• Colour film was becoming more affordable to make.
• In 1940 Larry Butler devised a process that would allow the creation of travelling mattes. 
• Three strip process, they are combined using an optical printer. 
• The best method until the 1950's. 
• Petro Vlahos invented the 'Sodium Vapour process'
• Sodium Vapour lights= 589.3 nm/s
• With this information Vlahos created a special camera film. Which has a prism within it.
• Only Disney has these cameras. 
• It wasn't very cheap to rent off them.
• Vlahos spent 6 months working on improving the blue screen method, eventually he developed the 'colour difference matte process'
• The colour difference matte was so successful that it remained popular for the next 40 years. 
• Technique developments meant that effects could be processed faster but very little changed until the      advent of digital compositing.

Blue becomes green

• Green became more and more popular colour to use green screens. 
• It was easier to lights than blue, green registers brighter on electronic displays and was a less common colour in clothing/ costumes.
• Many digital camera sensors capture twice the amount of green as they do blue or red (bayer pattern) making it easier to key a green screen. 

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