Tuesday, August 23, 2011

Stop Motion Animation Tightens Up with Intelligent Linear Rig

Production of the Glendogie Bogey stop motion animation was a smooth operation thanks to a clever design based on a HepcoMotion® linear actuation system. This film project, funded by BBC Scotland, was the sequel to the BAFTA-nominated production called Haunted Hogmanay. The story is about two friends that go in search of a fearsome monster called the Glendogie Bogey who lurks in caves under a golf course. Actors Rachel Stevens and Peter Capaldi provide two of the voices.

The film was the brain child of the Edinburgh based, Ko Lik Films, a company that specializes  in stop frame animation. This method involves clay models being moved, frame by frame, to create a sequence of fluid movement -- a time consuming task that can require as many as 25 camera shots to complete one second of film.

The production company was originally using a rig with a camera mounted on a hand wound helical screw, allowing the camera to be moved along the scene set. However, the process was neither accurate nor flexible, and resulted in increased production hours and compromised cost-efficiency. The company therefore sought the help of engineering designer and model maker, David Campbell and his colleague Michael Gormley.

“We explored proprietary motion systems for Ko Lik but they were too costly and over-specified for its needs,” said Gormley. “So we set about designing a system ourselves. And although what we came up with was a fairly straight forward two-axis system carrying a small load, there were several factors that made it a nifty bit of kit.”

The linear motion solution designed for the project was comprised of two PDU (profile driven units) by HepcoMotion with a SmartDrive stepper motor and controller. Designed to straddle the set it was a fairly long-winded development. “We had to translate exacting production needs into design engineering and both HepcoMotion and its motion control partner SmartDrive contributed a great deal in this regard,” added Gormley.

The rigidity that the HepcoMotion profile driven units provided was a crucial factor in the design. As the system is cantilevered, the vertical axis had to provide solid support for the motorized X-axis onto which the camera is mounted. Michael and David also had to contend with an element of bounce within the system but the rigidity of the beams and use of the motor to counterbalance the camera and camera head at extremes of travel ensures that this effect does not compromise the camera’s positioning accuracy.

The ability to move the camera a set distance to within .1mm accuracy, and most importantly provide a datum, was key to the rigs success from a production cost standpoint. When a sequence has been shot, the content is reviewed for quality, and if part of the scene needs to be re-taken, it is now easier for the production team to re-shoot because the exact camera position is now known.

The SmartDrive controller also provided other highly valuable automation features. Knowing what distances to move the camera to achieve the required visual effect is a complex task. Before using this linear motion design, a combination of mathematical calculation and intelligent guesswork on the part of the production team was needed.

“On the new system we have fed these algorithms into the controller so it has executable routines that the camera operators can just run,” explained Gormley. “It’s completely transparent to them.”

Gormley praised both HepcoMotion and SmartDrive for their ongoing advice on this project.

“In the greater scheme of things this was a fairly small job but both companies were only too pleased to give us the benefit of their knowledge.”

Learn more about profile driven units by HepcoMotion exclusively offered by Bishop-Wisecarver on our website: www.bwc.com

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