When John and I were filming Football For Zombies, we realized one of the scenes we would need in the short would be a field goal. The image of a football sailing through the goalposts is an iconic image. Since we were zombies, a football wasn’t good enough. We needed to have a head going over the goalposts.
We had a couple of head sprites we used in some animations from previous films, but given that we were making up Football For Zombies more or less on the spot, it would be too difficult to use those heads for anything other than sailing over the goalposts. We also wanted to show us shambling with the head and spiking it in the end zone. Mixing the head in with a moving body would be doable, but not under our time and budgetary constraints.
As luck would have it, my wife, Susan, had crafted us a head prop that we had planned on using in another video and never got around to using. The prop even came with a bloodied stump for a neck. This was going to work just great for carrying it and spiking it. Getting it to sail over goalposts was a whole different issue. We couldn’t just toss it over the post, that wouldn’t quite give us the shot we were looking for and the head was pretty delicate and wouldn’t likely survive the toss. So really kicking it was out as well.
We took a photo of the goalposts and figured we’d wing it in post production.
Goal Posts – They look so innocent
First, to maintain some level of continuity, we needed to get a head we could layer over the goalposts. No problem, I pulled out one of our green screens, unfolded it , set the head on it and shot some photographs.
Our fabulous head prop
Since both photos were of a much higher resolution than the 1920×1080 used for an HD video, I then cropped and resized the images, maintaining the necessary aspect ratio. I then opened Adobe After Effects and created two layers – one for the head and one for the goalposts.
We have to start from somewhere
I then applied the KeyLight effect, masking out the green screen from the head.
That’s looking a little better
I was then able to resize and reposition the head and then perform a simple animation where I put the head on an arc going over the goalposts. Notice the head actually starts outside the frame so it gives the appearance of moving in.
Just like we kicked it…
I animated the size of the head so as it moved from right to left it shrank, giving the illusion of sailing into the distance by keyframing the scale.
Giving the illusion of depth
Lastly I added some rotation. Now it looked like the head was sailing over the goalposts. But there was one problem. Since the head was layered in *front* of the goal posts the portion where it was above the crossbar was fine, but when it should have dropped *behind* the crossbar, it stayed in front. Doh!
To fix this, I added another layer using the picture of the goalposts and place it in *front* of the head.
It’s all in the layering
I masked out everything but the crossbar.
Now, when the head hits the crossbar it passes behind the crossbar layer, giving the illusion of passing through the goal. He shoots – he scores!!!