Flame: Camera Zoom Stabilization

I was recently asked to try and smooth out a camera zoom. The zoom was very steppy
due to it being shot during a snow storm with the camera operator wearing gloves.
I had never attempted this before but figured it must be possible using 2 point tracking.
After a bit of experimentation I finally got it to work. The trick was to use 3d z space
to nullify the zoom and then add a 2d scale to put a smooth zoom back into the shot.

1. Enter Action with your shot as Front, Back and Matte. Turn the matte off for the layer.

2. Add another axis and name it ‘track’.

3. Select the ‘track’ axis and enter the tracker in track mode with Scale turned on.

4. Do a 2 point track, selecting points that are as far apart as possible to get the
most accurate scaling data.

5. Exit tracker

6. In the channel editor select ‘axis1’ position z. Enter the following expression:
-(track.scaling-100)/100*camera.position.z This will nullify the zoom.

7. Still in the channel editor select ‘track’ scaling and copy and paste it onto ‘axis1’ scaling.
This will re-introduce the zoom. Now you can use the average tool in the channel editor to smooth out the zoom or change it completely.

 

Submitter: Alan Fairlie