How to add a shadow to a green-screened person so they stop floating
Ask Vizard Agent to add shadows and say the footage must stay as filmed. It cuts the person out as a mask, tracks both shoe soles in every frame, and casts a shadow from their own silhouette in the direction the scene's other shadows fall, with a soft dark patch under each foot, onto the untouched footage.
What do you type into Vizard Agent?
Say that only the shadow should be added, so nothing else in the shot gets regenerated. If something passes behind the person, like a vehicle, mention it, because a real shadow would fall across it too. Vizard Agent reads the direction of the sun from the shadows already in the scene.
Add shadows to the person. Keep the footage, the face and the sound exactly as they are.
What does Vizard Agent actually do?
It builds the shadow rather than asking a model to imagine one, because a generated shadow has no reason to stay attached to the feet or to agree with the direction of the sun. In the session behind this article it:
- Tried a generative edit first and rejected it: the clips came back at a different frame rate, details changed, and one shadow slid under the shoes at a different angle from a pole's.
- Cut the person out as a mask only and measured both shoe soles in every frame, 93 frames in one clip and 150 in the other.
- Projected a shadow from the person's own silhouette along the direction of the pole's and the truck's shadows, added a soft contact patch under each sole, and weakened it where the ground was already in shade.
- Found the composite running two to three frames late by matching output frames to source frames, fixed the timing so every sampled frame matched, and confirmed the audio was identical.
- Cast part of the shadow onto a truck passing behind the person, and told the user that clip still looked less natural because of how the original was keyed.
When does this not work well?
When the ground is uneven or the person leaves it. A shadow cast onto a flat plane looks right on pavement but wrong across steps, grass or an angled wall, and jumps make the contact patch hard to keep convincing. Then the shot may need relighting rather than a shadow layer.
Common questions
Why not just generate the shadow? Generated shadows drift. Vizard Agent builds one from the outline.
Which way will it fall? The way the scene's shadows fall. Vizard Agent reads them first.
Will the person change? No. Vizard Agent adds the shadow to the untouched footage.