Third world large gear manufacturing - GIF

[CharlesWaugh]

Political definitions aside . . .

How, when shaping a gear that way (on a shaper) do you get the right tooth form of an involute?
Do they have a master gear form that is on the same shaft as the gear and is then indexed against it?
Kinda like a follower on a metal lather making duplicates.

Clue me in here.

Thanks!