We went atop the Santa Bárbara Castle in Alicante to shoot the initial footage ourselves. We didn't have a tripod on hand (which I guess is pretty obvious by how shaky the whole shot is), so we made do with simple handheld pans of the surrounding area. After selecting one of the takes as footage for our final project, we had to make a tornado tear through the scene.

Ideally, I would have done a 3D tracking of the scene, modelled the city out, and properly rendered the tornado between the buildings. But I didn't think I'd have time for all that, so I had to settle for the cheaper option of masking the tornado via Nuke's rotoscoping node (roto_paint).

Everything about the tracking process was a mess. For some reason Nuke refused to do an automatic tracking, so I had to do it frame by frame which was pretty mind-numbing. I was as exact as possible, and still the end result was noticeably flawed.

The Sky, as well as all the colour correction, was also done in NukeX. I'm not entirely happy with the result - I didn't enjoy working with the tools NukeX provides compared to something like Photoshop. I suppose that's a matter of habbit, but I just couldn't manage to create a convincing overcast effect.

Cutting out the sky was once again done via Nuke's roto_paint node, meaning it was affected in the same way the tornado was due to my shoddy tracking skills.

Using a Volume Curve Field, I was able to shape the tornado the way I wanted it, and at the same time give it a "spine" that I could animate. There are probably better ways of achieving a tornado, but this one worked well for me.