For all the fans out there who have no idea, can you explain to us a little bit the process of making the visual effects for a movie? What do you work on and how long does it take to complete a scene?

The process is very long and tedious in most of the cases. Depending on the shot, we start with illustrations that come from the art department or with the video of what was filmed on set with the actors.

In the case of the dragon I started working with some illustrations and comments from the director. With all that information we started to experiment with different techiques to achieve in 3D everything that started with a sketch.

In other cases, like with the sand tornado, I started with a video coming from the set with the actors. On this video we insert our effects and we present them to the director who makes tons of comments, revisions and changes. After several tries and millions of particles we manage to finish the scene.

My effects for the dragon scene appear onscreen for less than a minute and it took me to make them over five months. It's the same in the case of the sand tornado.

What was the hardest scene to develop?

I'm not sure about the situation with the other studios that made other effects for this movie, but I can say that the extensions in the sets for the Ministry of Magic and staircases of the school were the most complicated ones to finish. They went through a great number of revisions and adjustments to manage the correct lighting.