How to add something to your footage that passes behind the person
Tell Vizard Agent what to add and what it should pass behind. A composite is a stack of layers, and by default the new element sits on top of all of them. So the person in the water has to be cut out as a separate foreground layer before anything can swim past behind them.
What do you type into Vizard Agent?
Say the depth relationship out loud, in the same sentence. "Add two sharks" gets you two sharks from Vizard Agent, correctly lit and convincingly animated, gliding across the front of the swimmer. That is not what anybody means by adding sharks to a pool. If you have a moment in mind, say that too.
Prompt
What does Vizard Agent actually do?
Generating the addition is the easy half. The half that decides whether anyone believes the shot is which layer ends up in front. So the person is masked frame by frame as a separate layer and the addition is rendered beneath, and the moment an arm crosses it is what sells the shot. In the session behind this article it:
- Extracted representative frames, checked the available editing routes and generated two realistic sharks lit to match underwater footage.
- Extracted each shark as a silhouette with transparency, verified the alpha was clean and corrected the cutouts where the larger silhouette had been clipped.
- Found the stretch with the most space around the swimmer, composited the sharks in and compared the rendered frame with the original at the exact overlay point.
- Switched to a direct render when concatenating the whole video timed out, keeping the original audio.
- After the first version was rejected on depth, built an animated mask of the swimmer and tested his layer over the sharks, checking the alpha format.
- Rendered with the swimmer in front, applied the mask to the full clip, confirmed the depth on a mid-section frame and re-checked the audio sync.
When does this not work well?
Some subjects can't be masked cleanly enough to carry depth. Splashing water, hair, spray and motion blur all produce edges no mask follows exactly, and a mask that flickers at the edge is more distracting than a composite with no depth at all. Low contrast makes it harder, and fast camera movement means tracking as well as masking.
Common questions
Can it add more than one thing? Yes. Vizard Agent prepares each one separately so they can be scaled and placed independently.
How do I check the depth quickly? Ask Vizard Agent for the one frame where the subject and the addition overlap.
What if the mask flickers? Tell Vizard Agent where, and the mask is rebuilt over that range.