Introduction to Motion Control: An IMIS event

Most of us remember the scene of Harry’s arrival at Hogwarts across the Great Lake with Hagrid, as the castle looms out at us from the darkness. Or have that legendary image in our minds of the Imperial Star Destroyer gliding ominously through deep space in Star Wars IV: A New Hope. But we also have most likely seen any of those commercials in which leaves of lettuce, slices of cheese and tomato and pieces of chicken fall exactly in place on top of a loaf of bread in slow motion. Funnily enough, all of these have something in common: they have been filmed using motion control.

What Is Motion Control?

The guys from Mark Roberts Motion Control, Peter Rush and Dorian Culmer, were there to tell us all about it. Motion control is a means to create difficult or “impossible” camera movements and special effects by accurately controlling the trajectory of the camera. Cameras are mounted onto robotic rigs controlled by a piece of software, and they’re able to move at very high speed with incredible precision. Therefore, the same movement can be repeated again and again, for example, to generate special and visual effects.

Although it seems like a pretty modern development, motion control actually started before digital times. Around the 80s, there was a very busy scene in London in particular, to create everything that wasn’t digital. As machines and skills improved in this area, they started filming models – which is how the previously mentioned Harry Potter and Star Wars scenes were made. Models were the main reasons for motion control; first they would film the model, and then they would integrate it with a background and other elements to create a scene.

London became the centre for commercials in the 80s and the 90s, with many big-time directors today, eventually moving on from commercials to film. A higher demand for fast machines surged, machines that could shoot a commercial in 1 or 2 days, or that could film 3 to 4 movements per day. This requirement was different of that in Hollywood, and it was Mark Roberts who started meeting this demand by creating these machines. The first one of the notably mobile machines was called “Cyclops”, which is still a company staple today, capable of filming 3 meters per second with great accuracy using high-end cameras such as the RED Dragon, flawlessly shooting in 6K.

Uses Of Motion Control

Motion control has countless uses, the main ones focussing on VFX creation and live action. Since the camera can follow exactly the same very precise path repeatedly, it is possible to get different layers (actors, background, foreground) that can be overlaid and matched together at the time of compositing. This can also be used to “clone” people, change foreground and background objects, for morphing – which is when one person transforms into another person or thing, a very popular use – or to put things together that couldn’t have possibly been filmed together.

Other uses within VFX include being capable of shooting a scene very accurately so that only one pass might be necessary in post – for example when the camera goes through a glass or an eyeball. It can also shoot forwards, backwards, change the scale (size of the movement) and the time of the movement. The latter is another very popular use, which is combined with compositing to create scaling shots – the most recent example is 2015’s Ant-Man. To create the main effect seen in the film, it is necessary to have exactly the same camera movement for the man and the background to later put them together, otherwise they wouldn’t match. Along the same lines, it is also possible to do scaling by taking footage that has been filmed without motion control, first by tracking the movement to create the initial camera path and then filming the foreground or background with the same path to put the scene together afterwards. Alongside with these, it is also widely used for VFX previsualisations.

Additional uses of motion control include high speed shots, with rigs that can film 4 metres per second (3 metres per second on tracks), which are popular with food commercials, since it can trigger other movements – this is how the ingredients fall on top of the bread. It is also utilised in animation – it is possible to create stop motion or go motion that have complex camera movements – in sports, such as the Olympic Games or Formula 1 and for space research.

Is Motion Control Necessary?

Sometimes it may seem that motion control is unnecessary. Why not fix it in post? Since the quality required in cinema features is an expensive and slow work path, it makes post-production for high resolution sequences also very expensive. It can also be very difficult when it comes to fixing incorrectly filmed VFX shots. Thus, it is normally more efficient to shoot correctly the first time using motion control rather than fixing it in post.

The one thing that motion control requires however, is lots of planning to be done properly. Therefore, the director usually gets together with the VFX Director and the DOP or Operator, and decides if it’s necessary, and if so, how to best work out the shots they need. The disadvantage is that most people aren’t actually aware or don’t know how long it takes to use motion control, or how much money they need to get it right properly. For this reason, if deciding to use motion control, it is best to get someone on board who is properly trained, knows the equipment required, how to use it and how long it will take. This way, the shoot will be properly planned and therefore the production will end up saving more by getting it properly done the first time, instead of wasting valuable resources such as time and money due to a wrong kit decision or last-minute changes.

Juan Cruz is a cinematographer and editor based in London. He is about to graduate from the University of Greenwich in the MSc Film Production.
In his films, he likes exploring technology-related dystopias. He also loves comedy and playing drums.