Avoiding VFX Problems on Set: Decisions Before the Shoot Day

I have been called into productions mid-shoot to fix a problem that didn't have to exist.

It happens more often than people realise. A call on the second day of shooting, sometimes the third. The voice on the other end sounds controlled, but a little too controlled. There is a shot that doesn't work. An element that doesn't sit in the plate. A frame that has to be rescued in post somehow — and nobody on set knows quite how.

When I arrive on location or join remotely, my first question is rarely technical. It is organisational: When was it decided that this shot would have a VFX component? Who defined what that component is? What brief did the set department receive?

In nine cases out of ten, there is a pause at this point. Then comes the answer I was expecting — the one nobody in the room is happy with: the brief wasn't as clear as it should have been. Or it came too late. Or it came verbally, to the wrong person.

That is the pattern I describe in this article. It is not a reproach — shoot days are pressure situations, and what goes wrong on them usually has nothing to do with a lack of care. It is an observation, and a recommendation for what can be changed.

The Background Nobody Decided On

An example I have seen in several variations. A scene gets shot — actress speaking, medium shot. The treatment says: "Background: dramatic scenery, added in post." That is all that is documented for this part of the frame.

On the shoot day, the actress stands in front of a wall. The wall is white, because nobody committed to whether it should become a greenscreen plate, a set extension, or a fully digital background. Three very different methods with very different on-set requirements.

Greenscreen needs the appropriate cloth in the right size, lit cleanly, with reference markers. A set extension needs a defined set whose transition to the digital portion is technically planned on the day — camera position, focal length, lens data documented. A fully CG background behind the person needs either a colour-key setup or a roto-friendly separation — and ideally a technical pre-discussion of what is coming next.

What actually happens on set when the decision is missing: the camera operator shoots as she sees fit. The lighting team lights the person, not the wall. Markers don't get placed. HDRI doesn't happen.

I then receive a plate later that doesn't sit cleanly with any of the three options. Greenscreen keying can be forced, but with edges and residual artefacts. A set extension lacks tracking foundation. CG background behind the person is possible, but more expensive to integrate, because the lighting situation and the spill have to be reconstructed.

In my experience, this isn't the expensive variant of a method — it is the penalty fee that comes due because a decision wasn't made in time. A properly prepared set extension costs a fraction of what rescuing an ambiguous plate costs.

My point: the decision "what is behind the person?" isn't a VFX decision in the narrow sense. It is a production decision with consequences for VFX, camera and lighting. It has to be made in the preparation phase — not on the shoot day, not in post, and certainly not implicitly, by nobody saying it out loud.

What I do today, when I am involved in prep, as a first step: every scene with a VFX component gets a written note specifying which method is applied. One sentence per shot. That note goes to directing, camera and lighting — before the shoot day, not on the shoot day. It is a tiny administrative step. It regularly saves the production five-figure sums in post.

The Object That Was Different in Reality Than in the Plan

The second case I encounter regularly: a physical object is meant to be digitally augmented, replaced or altered. A product in a commercial, a vehicle, a piece of equipment, an architectural element. The treatment describes the object — usually in general terms, sometimes with a reference image, rarely with technical specifications.

On the shoot day, the object is on set. And it is different from what was planned. Different proportions, different surface, different size, different reflective properties. Maybe it is the intended product, but in the wrong colour variant. Maybe it is a rental vehicle that doesn't quite match the model I prepared the CG extension for. Maybe it is positioned at an angle that makes the planned augmentation impossible.

I observe a recurring reaction on set in such moments: the production side waits for the VFX advisor's answer, then improvises. "Can we fix it in post?" — that is the standard question. The honest answer is usually: yes, somehow. But more expensive, slower, and with compromises that show in the final frame.

I have experienced multiple times that a digital element calculated in prep for the planned asset variant had to be entirely rebuilt to match the set reality. Materials recreated. Geometry remodelled. Lighting setup rebuilt. That is days, sometimes a week of additional work per shot — work that was not budgeted and has to be absorbed somewhere, often at the cost of final quality.

The cause rarely lies with set itself. It lies in the gap between treatment and reality. Whoever sources the physical object often doesn't know that the VFX prep is built on a specific variant. And whoever does the VFX prep often doesn't know what will actually be available on the shoot day.

In my view this is a classic interface problem — not a technical one. It can be defused by a single routine: before every shoot that involves a central physical asset, a brief alignment between the props/production side and the VFX side. What is actually coming? Which variant, which dimensions, which colour? Are there reference photos of the specific piece, not just of the model?

Five minutes of coordination in prep. Up to five days of saved work in post. The ratio is always the same.

What Departments Don't Tell Each Other

The third pattern is the silent one. No open conflict, no visible omission on the shoot day — the crew works professionally, every department does its job. And yet at the end, the data that post-production needs is missing.

Concretely: the camera department documents its work for itself — focal length, aperture, filters — but not in a form that VFX can use directly. Sensor data, lens distortion profiles, exact distance measurements between camera and main subject: these are pieces of information an experienced cinematographer has, but doesn't automatically record in his standard log.

The lighting team doesn't necessarily know that integrating a CG element requires an HDRI capture of the set lighting — a 360-degree recording of the lighting situation, ideally before the first take of a shot, with a chrome ball or equivalent capture setup. If nobody requests it, it doesn't happen.

Makeup may not know that a certain skin tone on the cheek will later be overlapped by a digital element — and that a green reflection on the skin multiplies the later compositing effort.

I call this the silent pattern because none of these points is a mistake in the classical sense. Every department does its work according to its own standards. What is missing is the cross-communication that says: "For this shot, VFX additionally needs the following information."

In my experience, there are two ways to resolve this. One is the presence of a person on set who actively performs this cross-communication — that is classical on-set VFX supervision, which the next article describes in detail. The other is a written checklist, agreed with the assistant director, that names the required data for every VFX-relevant shot — in the language of each department, not in VFX jargon.

Both ways work. What doesn't work is the assumption that the departments will somehow guess the requirements. They don't — not because they are incompetent, but because they cannot read minds. Nobody can.

What stays silent on the shoot day screams later in post.

What It Comes Down To

When I am called in mid-shoot, I rarely see a technical problem. I see a preparation problem that has fragmented into technical symptoms.

This is not an accusation. Shoot days are pressure situations — time, money, weather, talent availability, all hitting the wall at once. That decisions get deferred under that pressure is understandable. Except: VFX-relevant decisions don't forgive deferral. They get more expensive the later they fall.

My point for producers, agency project leads, directing teams: the most expensive VFX costs don't arise in post-production. They arise in the preparation phase — specifically when three or four decisions that could be made aren't made. Whoever brings experienced VFX consultation into that phase isn't buying an additional service. They are buying insurance against decisions that look harmless on set and turn expensive in the edit.

There is a rule of thumb I can derive from my projects: every hour invested cleanly in prep saves between half a day and two full shoot days of correction work in post. The ratio isn't spectacular. It is just extremely reliable.



Being called in mid-shoot remains part of my work. It doesn't have to be part of yours.