- Posts: 7
- Joined: Mon Jun 18, 2018 12:54 pm
- Real Name: Dustin Kerstein
The first way that comes to mind is to use the Trails tool to combine the images. Set the Alpha Gain to 0 in order to get a simple Add (Not the first Gain control; the Alpha Gain slider down below the Apply Mode controls). To counteract the exposure gain, use a BrightnessContrast tool and set this expression on Gain: 1/(time+1)
Gain is simply a multiply, or scale, on the luminance, so this formula will progressively darken the result based on the number of frames that have been rendered. I have added +1 to the time under the assumption that you're starting at frame 0, Fusion's default. If your global range starts at 1, then 1/time is what you should use.
I am not sure how small the number can go before you start running into
Trails is unlike other Fusion tools—its output is cumulative instead of being recalculated each frame, so when you use it, you have to start at the beginning and just let it render. If you need to make a change, you have to return to the beginning of the timeline and click the Restart button to clear its previous calculations.