How to set an object in your own footage on fire

Last updated 2026-08-31 · 7 min read

What is the short version?

The instinct is to hand the whole shot to a generator and ask for fire. That regenerates everything — the faces, the camera move, the background — and gives back something that is not your footage any more. The alternative is to burn one object and leave the rest alone.

1. Go to Vizard Agent and upload the shot.
2. Name the object that should catch fire.
3. Say plainly what must not change: the camera, the faces, the background.

What do you need before you start?

A shot where the object is clearly separable from what is behind it, and a clear statement of what must survive. Vizard Agent builds the mask from what it can distinguish, so an object that contrasts with its background is far easier to isolate than one that blends into it.

• The shot. As filmed, at full resolution.
• The object. Named specifically, not "the thing on the left".
• The rule. What must not be altered.
• The pace. How fast it should catch and spread.
• The sound. Whether it needs fire audio too.

What do you type into Vizard Agent?

Describe the physical behaviour, not the software. Vizard Agent works out the technique itself, so the useful detail is how the fire should start, how it should spread and what should be left behind — and, just as importantly, what is forbidden to change.

Prompt

Variants worth knowing:

• Say how it starts. Slowly from the surface, or all at once.
• Say what is left. Char, ash, or nothing.
• Ask for the light. Orange spill on nearby surfaces sells it.

What does Vizard Agent actually do?

Here is the order Vizard Agent worked in on a real burning-object shot. The whole approach turns on step fifteen onwards: it goes and finds real fire, ember and smoke footage rather than generating flames, because photographed fire looks like fire and rendered fire usually does not.

1. Reads the video's metadata and extracts sample frames.
2. Reviews the frames and checks what the earlier version of the project produced.
3. Extracts a full-resolution opening frame and frames from across the clip.
4. Builds a grid of frames to see how the camera moves.
5. Checks the audio streams and the original volume levels.
6. Searches the stock library for fire footage, then separately for embers, smoke and flame licks.
7. Downloads the fire, ember and smoke clips.
8. Searches for burning and crackling sound effects and downloads them.
9. Crops the object's area and inspects it closely.
10. Determines the object's full coordinates and builds a pixel coordinate grid.
11. Reviews the stock footage as a grid, scaled to the shot.
12. Builds the object mask and verifies it, then refines it twice — once by hand, once by colour segmentation.
13. Tests processing speed, renders trial frames and validates them before committing to the full render.

Step twelve is where the quality lives. Vizard Agent builds a mask, looks at it, refines it, looks again — because a mask that is a few pixels wide of the object puts flames on the background and gives the whole effect away instantly.

What does the result look like?

The shot this page is written from measured 1920x1080, H.264, roughly 30fps, 12.34 seconds with AAC audio. The camera move, the framing, the background and everything not on fire came through identical to the source, because none of it was regenerated.

What changes is confined to the mask: flame across the object's surface, thin smoke, embers, and the orange light that spills onto what is nearby. The crackle sits under the original audio rather than replacing it.

When does this not work well?

Compositing an effect into real footage is fundamentally a masking problem, and masking has honest limits that no amount of processing removes. Vizard Agent shows you the mask it built and where it struggled, rather than presenting the finished shot as though nothing had been difficult about it.

• Objects that match their background. White on white is very hard.
• Fast motion blur. The edge is not where it looks.
• Objects that leave frame. The mask has nothing to track.
• Transparent or fine detail. Hair, mesh, glass edges.
• Long shots. Every frame has to hold, not just the first.

How do you fix a result that came back wrong?

Describe what is wrong with the fire, not with the mask. Vizard Agent keeps the mask, the coordinate grid and the sourced footage, so intensity, timing or spread can change without any of the isolation work being redone.

• "It catches too fast." Re-timed across the same frames.
• "Flames are on the background." The mask is refined and re-composited.
• "Not enough light on the surroundings." Firelight spill increased.

How does Vizard Agent compare to doing it yourself?

By hand this is rotoscoping: masking an object frame by frame, then layering fire elements, then matching the light. It is the kind of work that takes a compositor a day. Vizard Agent builds the mask programmatically and verifies it by looking at it.

Common questions

Why not just generate the whole shot burning? Because you lose the shot. Vizard Agent composites into the original so the footage stays yours.

Can it burn a person? No, and it should not. Vizard Agent handles objects, props and materials.

Does the fire look real? It is real fire, filmed. Vizard Agent composites photographed flame rather than rendering it.

What about the smoke? Sourced separately. Vizard Agent layers smoke and embers as their own elements over the flames.

Can it add the sound? Yes. Vizard Agent sources burning and crackling effects and mixes them under your original audio.

Will the light change on nearby objects? If you ask for it. Vizard Agent adds the orange spill that makes the effect believable.

How long can the shot be? Short is safer. Vizard Agent has to hold the mask on every frame, and longer shots offer more chances to fail.

Can I preview it first? Yes. Vizard Agent renders trial frames and validates them before the full render.

What if the mask is slightly off? Say where. Vizard Agent refines the mask and re-composites rather than starting over.

Does this work for other effects? Yes. The technique is the mask, so Vizard Agent uses the same route for water, frost, rust or dissolving.

What if the object is partly behind something? Harder, but often possible. Vizard Agent builds the mask around what is visible and tells you where the occlusion causes trouble.

Can it keep the original audio? Yes, and it usually should. Vizard Agent measures the original levels first so the fire sits under the existing sound rather than burying it.

Is this the same as a filter? No. A filter changes the whole frame; Vizard Agent changes only what is inside the mask, which is why the rest of the shot survives.