(Do not share this, it is your paid privilege!)
This did not go perfectly, some of the fish became invisible. I have to figure out why. I suspect it has something to do with contrasting colors. Even though the effect is called "green screen" I can actually use any color, and I think it will help if the special effect color is the exact opposite of the subject's colors. It's also unfortunate iMovie's green screen effect is a lot more primitive than any Hollywood quality green screen effects.
I used a flat piece of green paper because any shadow cast by the paper or any reflection will confuse the computer. It had to be very flat, cast no shadow on the table, and reflect no light. This also makes it tricky to mount the subject because certain angles are better for the green screen but not necessarily better for physical stability or filming comfort. I wanted to pull the fish but the fish itself would cast a shadow on the paper. That's why I pushed the fish instead.
I wanted to avoid robots and similar effects but it seems I may have to experiment with those as well in case the green screen does not work out.
- i v