3. Green Screen

Green screen is used in almost all films in recent years. It is used to be able to put subjects in almost any location a person can imagine.

I chose to do this work on my own as it wasn't as big a task as the visual effects composition.

Before I chose how to light my scene, I needed to decide on a back ground. The back ground I chose is lit from the left, with lots of shadows on the right-hand side of objects. I lit my set accordingly, so I would match the scene. I had an idea of myself staring into the camera as it slowly panned out revealing more of what was behind me, in this instance; as the camera would pan out, it would reveal more and more destruction.

The camera I filmed on was an HDV camcorder, mounted on a dolly. I chose to use the dolly to pan out rather than just zoom out so I could maintain eye level with the camera. The only set back of using this HDV camera was it captured with the file type ".mov" which I was unable to import to either After Effects or Premiere Pro, so to solve this, I converted the footage into a loss-less file type that was compatible with the software I would be using.

To key out the green background; I used Premiere Pro's ultra key tool. I found this to work a lot better than After Effects' key light tool, as with it; the shaded side of my face became transparent. Adjusting the pedestal feature within ultra key, I was able to get a near perfect colour removal.

Original Footage -- No Key

Ultra Key added, but shadow of me and seem of curtain
still visible

Ultra key active, pedestal setting at 100% removes
original background completely

The background I chose was of multiple destroyed skyscrapers settling in rubble, however, I wanted to make it look as though they had only recently been destroyed, so to do this; I wanted to add flames and explosives to different areas of the image to represent that they had been purposely destroyed, rather than destroyed by the elements over time. As my footage panned out; The back ground would have to as well, so to do this I key framed it's scale and blur from start to finish  to match the perspective and focus of my footage.

Even though I lit the set correctly, I still looked very saturated in comparison to the background, so I lowered the saturation enough to look like I could have been in that environment. The image also had a very small fraction of blue in it, so I used the fast colour corrector tool in Premiere Pro to add a similar amount to my footage.

Once this had been done, all that was left was to add the flames in the background, and to do this; I used after effects. As the background was now a moving image, I would have to track points within it for the flames to follow. I added individual coloured pixels to the background using photoshop, so that the motion tracker tool could determine what to follow easier.

Video co-pilot is a tutorial website that teaches it's users to use after effects and make they're own effects. It provides users with ready made effects available to add to their own clips, e.g. stock footage. Stock footage is a pre-keyed clip of things like fire, water, explosions, smoke, and many other things. I used some of these clips in my green screen to create the effects.

Once the final video had been made, it was brought to my attention that it looked like it could be used as a teaser trailer for a TV show. So to make it look more like an advert, I created a TV bumper which pops up to show the name of the show and the time it is aired.

Here is the completed video:

I really enjoyed making this video as I learned to use many new tools in after effects. If I were to film anything like this again; I would talk in the video. I think this would make it look more realistic because even though the video I recorded is actually moving, I only have very subtle movements which looks almost like a still image, whereas if I spoke; it would be obvious that it is a video clip.

2. Tracking

Motion tracking is used in films to allow an effect that wasn't originally in a piece of footage, to follow a subject point through a clip. It is easier to track a point that contrasts well compared to a point next to it, i.e. a black spot on a dalmatian.

For my tracking video, I had an idea of super powers. My first means of doing this involved tracking flames to points on my arm that I would mark with coloured spots. I did film this and edit it using after effects, but I was really unhappy with the results. It was a measly six seconds longs and as you can see, the stock footage I used was very cartoon-like and unrealistic:

After seeing this, I thought I'd try using lightning bolts whilst filming against green screen, using after effects.

I used pieces of coloured tape around both of my middle fingers to track and they worked extremely well against the green background. 

Once I had tracked both points, I parented two null objects to them. To add the electric, I used an effect called "Advanced Lightning" and used the two-way strike. This is where things became difficult.

There are two points in the two way strike: Origin and direction. Normally to make objects move with the now-tracked null objects; I would use the pick whip tool to parent an the object to the null, however, as this is an effect, and not it's own footage; I was unable to do it, so I had to use the expression pick whip to parent each point of the lightning to the POSITION of the null-- not to the null itself. 

Once I had figured this out, it became a lot more straight forward, with only minor tweaks needing to be made to the behaviour of the electricity.

Here is the finished video: 

If I were to film something like this again, I would spend more time on it to rotoscope around my hands, as in this footage, the electricity overlaps onto the back of my hands, making it look less realistic.

(Background for video created by Ben Reeves)