The front source mesh defines the original shape of the image in each frame of the front clip.

To define the source mesh for the front clip:

1. Go to the first frame of the clip.
2. In the Morph menu, click Front Source.
3. Add a mesh over the area to be morphed and modify its shape to match the image.
4. Make the front source mesh match the image at each frame of the front clip. You can either modify the mesh manually or use the Stabilizer to track the movement in the front clip.