There are a number of ways to get ripples in AE. You would need to rotoscope the dog so that he's not rippling and then mask him out as he runs "into" the portal. Not sure how to rotoscope? Read this: After Effects Help | Managing and animating shape paths and masks
1. Is there a way to make a selection for rotoscoping without using the Pen tool, in a similar way to the Quick Selection tool in Photoshop?
2. Is the idea that as soon as the ripples begin I need to rotoscope each and every frame of the moving (not static) dog to prevent it from rippling? So if there are 10 seconds of rippling I need to make sure there is a mask on the moving dog for 30frames x 10 seconds?
You can use a Rotobrush or Roto by hand. 10 seconds is an awfully long time to be staring at an effect like a dog jumping through a wormhole.
And even better technique would be to green screen the dog and shoot a clean plate for the wormhole. You just need to match camera position and angle for that to work.
If you are going to Roto then it's a really good idea to shoot a clean plate also. That's why even the big boys with lots of experience hire a visual effects supervisor.
MAybethen it's a really good idea to shoot a clean plate also. That's why even the big boys with lots of experience hire a visual effects supervisor.
Maybe this simple Roto demo will give you an idea of how to do this by hand.
And, remember, you don't have to rotoscope the whole dog - just the part that would be affected by the effect. If you plan with a storyboard and a good edit in mind, you won't have a whole dog for ten whole seconds. As Rick said, that's a LONG special effects shot.