Proof Of Concept – Colour Keying

I decided I would do a series of short test animations so I could identify and flag the problems that may arise during my short animation. As stop motion animation is a hands-on craft I wanted to test out the various techniques I have been reading about. Earlier in the week I purchased various coloured card and used the bright green one to try and key out and replace the background in a simple animation. The subject of the animation would be a spiderman toy that I found on the street some years ago. It’s an almost perfect subject as the toy has plenty of moveable parts.

Using white tack, I stuck the card to the wall and also the desk using a gentle curve to eliminate the corner. This will give me the best chance of integrating the action figure into a scene once the green card is keyed out. I then used a desk lamp and a smaller conventional lamp (with the shade removed) to light the green screen from either side. This would hopefully obliterate any shadows cast by spiderman. I used my larger, but slightly duller, desk lamp to illuminate the action figure. Both the large desk lamp and the shade-less lamp were wrapped in baking paper to help diffuse the harshness of the light.

I used Dragon Stop Motion to capture the frames for this animation. I tried various software and Dragon was the one I felt most comfortable using. Many of the others felt a bit cheap and didn’t seem to offer the same functions as Dragon does. After some research into it, it appears that Dragon is the choice of many professional stop motion animators, so I’m in good company. The camera is connected directly to the laptop and set up for remote shooting. The camera allows live view so it’s extremely easy to line up shots on a frame-by-frame basis.

I began shooting a simple sequence involving spiderman appearing to wait impatiently and then walking towards the camera and out of the shot. As this sequence was all about the process of keying, I didn’t bother with a storyboard, or even a script of any sort. I just made up the actions as I went along. It quickly became apparent that when I shoot a short animation for real that these elements will be key to the success as I was not sure of how the timing would be rendered. From my years of experience animating with Flash I understand the concept of movement and frames and how to make something move slower or faster over time, but to actually do it by hand is completely different when there is no reference to work from.

In total I spent about two hours shooting 106 images at 12fps, producing nine seconds of rendered footage. I learned more in those two hours of hands-on experience that I did in days of researching. I used the white tack to keep spiderman’s feet firmly stuck to the ground, which was fine for the first part of the animation but when it came to making him walk I found it really hard to unstick him without upsetting the other limbs and had to try match up the newly unstuck spiderman with the previous frame. When walking I couldn’t keep him balanced on one leg so you can see in some frames the piles of white tack under his lifted foot and I’m holding a screwdriver at his head to stop him from falling over. If this was my final important animation I would not have been so crude. Also, as it turns out, old spiderman was not the perfect subject for stop motion because although he has many moving parts, they were so rigid that when I moved one piece, the rest moved with it. It may be a case of dismembering him and removing dirt/grit, but right now I don’t have time to perform surgical operations on plastic action figures.

I then exported the stills as a Quicktime movie and opened it in Adobe After Effects. As I’m a total newcomer to After Effects this is kind of where I’m at at the moment. I quickly tried out the keylight effect to remove the green screen and it only worked okay. I may need to tweak the settings but it seems that the green screen either wasn’t lit correctly or that spiderman was too close to the green which reflected back onto him. I will do some more playing around with this and do some research to see how to go about actually removing and replacing the green background.

The plan was this weekend to borrow a video camera and film a bustop so I could drop my animation of spiderman waiting into it, to have him waiting for a bus, walking away and then have a bus pull up. I tried to borrow one of the university’s Flip cameras as they are small and portable and would do the job nicely. As it turns out, they are only available to the third year students. This annoyed me because I feel fourth year students should get preference on what technology to use for their dissertation. I ended up being given a bulky Sony video camera, bag, cables, booklet and charger for my nine seconds of footage! To add insult to injury, when I got home I found that the camera takes tapes and I wasn’t given any to record on. That was Friday afternoon and the school office was shut. So I will have to wait until Monday to get a tape so I can film.

Here is the green screen footage and I will post more when I get  working on it.

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