How to replace the ground in a video and keep the shadows that fall on it
Ask Vizard Agent to replace only the ground and keep the person, shadows and camera move. It builds a flat tiled texture for the new surface, tracks the ground plane in every frame so the texture stays fixed under the feet, and transfers the original light and shadows onto it so sun patches and the walker's shadow survive.
What do you type into Vizard Agent?
List what must survive, not just what changes. "Replace the road with paving" is satisfied by a flat texture that ignores the light, which is what makes a ground swap look pasted in. Naming the shadows and the camera movement tells Vizard Agent the new surface has to behave like the old one.
Replace only the road surface with clean, light-grey paving. Keep the person, what they're holding, the shadows, the lighting and the camera movement exactly the same, tracked through the whole clip.
What does Vizard Agent actually do?
It treats the ground as a flat plane seen in perspective, and the light falling on it as a separate layer. The new texture provides the material, while the original footage keeps providing the shading and the shadows. In the session behind this article it:
- Masked the ground, generated an overhead paving texture and rebuilt it into a tile layout so the joints line up and no crack repeats.
- Tracked features only on the ground and solved its perspective in every one of 301 frames, so the paving stays fixed under the feet.
- Turned the blurred original ground into a lighting layer and multiplied it onto the paving, keeping the sun patches and the moving shadow.
- Protected a fallen leaf with its own mask once it appeared.
- Found halos on the moving feet came from the layers drifting three frames apart, forced every input onto the same frame count, refined the edges, and told the user plainly where some fringe remained.
When does this not work well?
When the ground is not flat. Steps, kerbs and slopes break the single-plane assumption, so the new surface bends wrongly where the real one changes angle. Busy foreground edges, like loose laces or a trailing sash, also leave some fringe that is hard to remove completely.
Common questions
Why does the new ground slide under my feet? It is not tracked. Vizard Agent solves the ground's perspective per frame.
Will my shadow still be there? Yes. Vizard Agent carries the original light onto the new surface.
Will there be edges around me? Some fringe can remain. Vizard Agent tells you where.