[smeyer]

But won't the players have moved roughly as much as the ball from photo to photo (since they're moving at about the same speed)? I suppose as long as the players haven't moved into the space where the ball used to be you could still trivially use that space to replace the ball in an earlier image.

[jessaustin]

This is a guess but maybe if they have multiple moving objects they just figure out which one is shaped like a ball?

[oska]

First, let's assume the ball is shaped like a sphere...

[plucas]

What is its radius in meters? Can I assume it is a unit sphere?