- “Mary Poppins,” the 1964 Disney film about a flying, magical nanny isn’t just a beloved classic – it’s a monumental movie in the history of filmmaking.
- The film is regarded as Walt Disney’s crowning live-action achievement, as the only Disney film to ever be nominated for the Academy Award for Best Picture in his lifetime.
- What’s often overlooked is that the film was also that year’s Oscar winner for Best Visual Effects.
- To bring “Mary Poppins” to life, Disney hired the engineer and inventor, Petro Vlahos. His innovation eventually became the basis of the modern green screen.
The scene you’re about to watch is perhaps one of the most important and influential sequences in the history of cinema. OK, this could use some explanation. This is a scene from “Mary Poppins,” a 1964 classic directed by Robert Stevenson. It’s a film often regarded as Walt Disney’s crowning live-action achievement, being the only Disney film to ever be nominated for Best Picture in his lifetime. But there’s something else that’s often overlooked about this film. It was also that year’s winner for Best Visual Effects. Now for a film featuring a magical flying nanny, you might not find that to be surprising at all. But it’s this overlooked achievement that helped “Mary Poppins” change the course of film history forever.
Like all forms of art, films have always relied heavily on bringing our imaginations to life. As films evolved, this posed a great challenge for early filmmakers. Imagination had no boundaries – but film did. At the time at least. Early on, simple camera tricks were used to make the impossible look possible. George Méliès, one of the first pioneers in visual effects used a technique known as double exposure mattes to achieve this feat over a hundred years ago. A man with multiple heads. He did it by putting a glass panel in front of the camera and painting black marks over specific sections to block the light. He would then rewind the film, and set up an opposite matte to fill in these blanks individually. Then voila! Despite its many limitations, the double exposure mattes were used for many years, until something a little more familiar to us arrived on the scene.
This is the blue screen, developed by Lawrence Butler and it looks and works similar to the green screen we use today. With the arrival of colour films, Butler realised he could put a subject in front of a specific colour, then remove that exact colour to isolate a subject from its background. The isolated subjects would then be placed on top of a pre-shot background known as a plate to create a single seamless image. This is the start of what we now commonly know as chroma key. This method was first used in 1940 for the film “Thief of Baghdad” but it also came with many issues. The colour blue was selected mainly because it was a colour farthest from the skin tone. But this meant that any costumes or props with a blue hue would simply blend in and disappear with the background. And if the lighting wasn’t perfect, it would end in these blue halos that you see around the actors.
So when Walt Disney acquired the live-action film rights to “Mary Poppins,” they wanted to take the opportunity to push the technology even further. Especially for one particular sequence, where live-action footage merges with Disney’s classic hand-drawn animations for over 16 minutes. But instead of hiring a special effects artist for the job, Disney instead asked for help from the engineer and inventor Petro Vlahos.
So, what did Vlahos do to begin? Well, he got rid of the blue screen. Fully aware of its limitations, he sought for another colour to replace it. His answer? Yellow! Well, more specifically, the yellow hue from sodium gas. The same light you see in street lamps. Vlahos knew that sodium gas produces light at a very exact wavelength, 589 nanometres. In comparison, the blue used in blue screen ranges from 435 to 500 nanometres. By shrinking the range of wavelengths, Vlahos knew he could greatly improve the accuracy when isolating a subject. This already solved many problems from its predecessor. For one, things didn’t have to be lit as perfectly. And there were no limitations on the colours of props or costumes. For example, Dick Van Dyke could wear this blue bow tie and socks, and because sodium gas emits a very specific hue of yellow, he was also able to wear a blazer with yellow stripes. To achieve the effect, the actors would stand in front of a white screen lit by a yellow hue from sodium vapour lights, hence its name, the sodium vapour process. Unlike the blue screen, which required tampering with actual film strips to achieve the effect, Vlahos’ method was completely within the camera. He did this by creating a unique prism that was designed to isolate the 589 nanometre hue from the rest of the colours. This simplified the process of creating a more accurate matte, the silhouette image that’s vital to the process. The result was astounding. Even by today’s standards, it’s difficult to find a fault. Isolating a more specific range of wavelength allowed for a crisper image, practically eliminating the halo effect of the blue screens. You need to look no further than this veil that Julie Andrews is wearing to see how impressive this technology really was. Up until then, isolating a material as fine as a veil was deemed impossible until Vlahos’ new invention. And it was this technological marvel that earned Vlahos the Oscar for Visual Effects. There was an issue, however. Despite multiple attempts to replicate it, Vlahos could only create just one working prism which meant there was only one sodium vapour camera, in the entire world. After showing its capabilities in “Mary Poppins,” other studios and filmmakers fought to use it. And this single technique would go on to be used for almost 40 years, in notable films like Alfred Hitchcock’s “The Birds” and the original “Pete’s Dragon.”
After the success of “Mary Poppins,” Vlahos would go on to further develop and improve the chroma key process. The result was what eventually became the basis of the modern green screen. For this reason, Vlahos is often regarded as the man who made the modern blockbuster possible. Without Disney’s gamble and Vlahos’ ingenuity and innovation, we might have never seen “Mary Poppins” on the silver screen, not to mention films like “Star Wars” or “Jurassic Park.” With “Mary Poppins,” Vlahos not only gifted generations of people with one of the most beloved classics of our time, but a legacy that can make all of our wildest imaginations come true.
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