I asked Russ Wharton to detail exactly how he has gone about increasing the size of the worm in one shot from Gone Fishing. Here’s what he has said… Interesting if you are into digital VFX…Anyway, here are his words…
If you know you need a bigger worm before you film, then film the actor without the worm (have him hold a small white headed pin instead) and film the worm full frame against a keyable background (like a greenscreen). Then the worm can just replace the pin. Job Done.
If, however, you decide you need a bigger worm after the fact, then this is one way….
— Not full details here (to keep it short and sweet) but enough to follow along —
For this tasty meal you will need the following ingredients:
We need to scale the worm. Which means we need it separate from its background.
Backgrounds blend into foreground edges, even more so with motion blur. You can pull out this bleeding with keying tools and colour correction but sometimes (as in this case) it doesn’t leave much foreground to work with :o(
Scaling softens the image.
Speed of movement won’t be accurate, big things have weight and move slower.
Build a Superworm!
Take some neat (no mo blur) frames into photoshop and use to create just one new superworm image. Scale where poss and clone in some detail so we’ve got a nice sharp 200% worm to work with. Save out a .psd image with an alpha channel.
Animate the worm – put this image into AE and deform it over time (slightly embarrassed to say I used the new puppet tool – I thought this was a bit pointless when I saw they introduced it in the new version, but for this it was perfect!).
Copy the original worm motion for this. Then slow it down! Our 200% superworm will be weightier than its smaller sibling. I slowed it down by a third.
Tip – If you want an easier animating life, have one of those fancy computer things do the work for you (that’s what they’re for). Use motion tracking to follow the plate your matching (in this case the hand) and you’ve already got half the movement done! Very useful on slow moving objects, where hand animated imperfections show up easily.
Clean the background plate: anywhere the old worm shows up behind the new one you’ll have to remove it! Its sometimes easiest to use an earlier part of the footage where the plate is clean as source.
Add edge feathering/light wrap — Remember the background bleeding that was such a problem in the first place? Well now we need to put it back! Using a duplicate of the background plate that’s been cut out by a feathered edge matte of the worm.
Add a touch of motion blur and season to taste (depends on the shutter speed used when filming).
Put anything back on top of the worm that needs to be there — like fingers and grass. Again, use cut out duplicates of the background plate.
Finally, add a sprinkling of minor colour correction (to the worm, don’t touch the plate) and leave to render for about 10 mins (depends on oven speed).