What were the hardest shots to accomplish on Deathly Hallows, Part 1?
Tim Burke: I think the hardest things were the characters. The creatures and Dobby. People had to relate to Dobby, to empathize with Dobby to believe he would die. People are used to seeing good and bad CG characters. If Dobby didn’t look like he had a soul, we would have lost the emotional moment at the end of the film. I thought Dobby would be the hardest character, but with the skills of our brilliant animators at Framestore, he wasn’t that difficult to execute. And we had brilliant reference performances, which helped us nail the characters.

How did the role of visual effects change in this film compared to earlier films?
We’re definitely doing more. The set design has become more expansive. The production scheduling and knowledge of how we could film on green screen using exterior partial sets on the backlot has changed. Especially on the last film. Because of the complications of scheduling two films, we had a lot of location work and couldn’t go on location. [Production designer] Stuart Craig has become familiar with us, so he created partial sets and we created digital sets. So, that’s something production has taken on board. And, because we’re able to do more rigid body dynamics and destruction work, we have no miniatures at all now.

For Part 2, we’ve done away with Hogwarts. It was such a major job to stage the battle of Hogwarts, and we had to do it in different stages of production. We had shots with complex linking camera moves from wide overviews, to flying into windows and interior spaces. So we took the plunge at the end of 2008 and started rebuilding the school digitally with Double Negative.

It’s taken two years – getting renders out, texturing every facet of the building, constructing interiors to see through windows, building a destruction version of the school. We can design shots with the knowledge that we have this brilliant digital miniature that we can do anything with. With a practical Hogwarts, we would have shot it last summer and been so tied down. Instead, as David Yates finds the flow and structure, we are able to handle new concepts and ideas.

Have these changes affected your role as visual effects supervisor?
It’s dawning on me that supervisor is the wrong name. Given the level of what we do now, we’re directing the effects and to direct the effects, you have to understand what the director wants. It’s like composing music. David [Yates] uses words to describe things that are not visual. Ridley Scott draws sketches that I can almost hold up at the end of the day and say we did what he wanted.

David is more enigmatic. He would say, “The horcrux needs to be malevolent.” So you have to take a big leap. You have to get inside his head to know how to interpret that. Sometimes, you have to know how to interpret silence. Maybe silence isn’t a good thing. And I had three producers to interpret, too.

You will finish the last Harry Potter film in a couple months. How does that feel?
It didn’t sink in until June last year, when I slowly started seeing different departments leave. We were in our offices working on Part 1, and the art department left, the construction department left, but we were working flat out. We were on our own in a building that was being knocked down because Warners is turning it into a film complex. We left just before Christmas.

I took a tour before the end. The sets were overgrown with weeds. I watched the diggers come in. The reality of leaving the studio where we made the films and seeing it knocked down was so sad.