AE transform - looking for discussion place

[Kisiel]

Hi, 

I have a feeling that's not the best place to ask this question, and I would be grateful if someone could point me in the direction of a better one.

I have short handheld footage of a girl standing in front of a flower wall.
The ask is to lengthen her legs, so she appears a bit taller.
Since she does not move, I don't mind stretching the whole image from her waist down, but I don't know how to do it.
I can track her belt in the frame, but I have no idea how to stretch the footage from her waist down, not the rest. 

[Mylenium]

You would likely mask her out, precompose the result and apply a bit of Puppet tool magic to extend the legs. Likewise, you'd then simply patch up the background and then add your modified lady on top. Nothing too special, it just requires a bit of tedious work.

Mylenium