How to swap a recurring prop for something else everywhere it appears

Last updated 2026-08-30 · 7 min read

What is the short version?

Replacing one object throughout a video is two problems wearing one coat: making a clean cutout of the new thing, and knowing where the old thing is in every frame. Neither is hard alone and skipping either shows immediately.

1. Go to Vizard Agent and upload the video plus the replacement image.
2. Say which recurring object it replaces.
3. Say the original should disappear, not be covered.

What do you need before you start?

The video and a usable replacement image. Vizard Agent will cut the image out itself, so a plain background helps enormously, and the object being replaced should be visually consistent enough to be tracked across the whole clip.

• The video. However long.
• The replacement. An image, any background.
• The target. Which recurring object goes.
• The behaviour. Should it move as the original did?
• The scale. Same size, or larger.

What do you type into Vizard Agent?

Say "replaced" rather than "covered". Vizard Agent treats those differently: covering pastes the new asset over the old one and leaves its edges showing, while replacing means the original is removed and the new asset takes its place in the frame.

Prompt

Variants worth knowing:

• Same motion path. The replacement follows the original's track.
• A different scale. When the new asset reads better larger.
• Only in some shots. If the swap is not needed throughout.

What does Vizard Agent actually do?

Here is the order Vizard Agent worked in on a real prop swap across a two-minute clip. The check that most people skip is the seventeenth: it put the cutout on a checkerboard to confirm the transparency was genuinely clean.

1. Inspects the attached character image and samples the video's timing.
2. Reviews the sampled frames and the rest of the timeline.
3. Checks the analysis and cutout capabilities available to it.
4. Reviews all the sampled scenes to see where the prop appears.
5. Creates detailed reference frames and asks for a visual overview of every appearance.
6. Creates a transparent cutout of the replacement and inspects it.
7. Refines the cutout against its green background and verifies the result.
8. Checks the transparency on a neutral background, then views the cutout on a checkerboard.
9. Measures the original prop's position through the footage, reviews representative frames for tracking accuracy, and inspects the detected bounds at one-second intervals.

Step 8 catches the thing that ruins these edits. A cutout that looks clean on white can carry a pale halo from its old background, and that halo is invisible until the asset sits on something dark — by which point it is in every frame of the video.

What does the result look like?

A two-minute vertical clip in which the original prop no longer appears anywhere. In its place, at the same positions and following the same movement, sits the replacement asset — composited with a transparent edge so nothing of the old object or the new image's background shows.

The tracking is what makes it read as a replacement rather than a sticker. The new asset arrives where the old one was, moves when it moved, and leaves when it left.

When does this not work well?

Swapping an object everywhere depends on the original being findable in every single frame and on the space behind it being reconstructable. These are the cases where the footage rather than Vizard Agent sets the limit on what is possible.

• Occlusion breaks tracking. An object passing behind something is lost.
• Motion blur has no clean edge. Fast movement smears the target.
• Similar objects confuse the detection. Two yellow things, one intended.
• The background must be rebuilt. Removing the original leaves a hole.
• Rights apply to the replacement. A character you do not own stays not yours.

How do you fix a result that came back wrong?

Name the moment that is wrong and say what should have happened there. Vizard Agent keeps the cutout, all the transparency checks, the measured positions and the per-second tracking detections, so a missed appearance can be added without redoing the cutout work.

• "It vanishes at 0:48." Added from the position measurements at that interval.
• "There is a white edge on it." The cutout is refined and re-verified on a checkerboard.
• "It should be bigger." Rescaled; the tracking stays as measured.

How does Vizard Agent compare to doing it yourself?

By hand this means masking the replacement in an image editor, then keyframing its position across every frame the original appears in. On a two-minute clip that is hundreds of keyframes, which is why most people cover the object rather than replace it.

Common questions

Does the original really disappear? Yes, if you ask for replacement rather than covering. Vizard Agent removes it and rebuilds behind.

What image should I supply? Anything reasonably clean. Vizard Agent cuts it out and then refines the edge itself.

Will the replacement move like the original? Yes. Vizard Agent measures the original's position through the clip and follows it.

How does it check the cutout is clean? Vizard Agent views it on a neutral background and then on a checkerboard, where haloes show.

Can it handle several appearances? Yes. Vizard Agent builds an overview of every appearance before starting.

Why check transparency on a checkerboard specifically? Because a pale fringe left over from the original background is invisible against white and obvious against dark footage. A checkerboard shows both at once, before the asset is in two thousand frames.

What if the object is partly hidden? Occlusion is the hard case here. Vizard Agent reports where the tracking loses the object.

Can I swap several props at once? Yes, though Vizard Agent needs a separate cutout and tracking pass for each one.

Does it work on people? Vizard Agent treats that as a different job, with its own article and its own consent questions.

Can the replacement be animated rather than a still? Yes. Vizard Agent composites a transparent clip the same way it composites a still, following the same measured track, which suits a character that should move rather than merely travel.

How long can the clip be? Two minutes here, and length is mostly a tracking cost. Vizard Agent measures the prop's position throughout, so a longer clip means more frames to check rather than a harder problem.

Does the replacement need a transparent background already? No. Vizard Agent cuts it out of whatever background the image came on, which is why the refinement and checkerboard steps exist rather than being skipped for a ready-made asset.

Does Vizard Agent check the finished video? Yes. It reviews the tracking accuracy on representative frames before delivery.