A net movement can be small even when large quantities travel in both directions. If a film replaces two opposing flows with one narrow arrow, it may hide the activity the story is meant to explain. Decide whether the approved graphic reports movements separately or only their net balance before commissioning the animation.
The European Commission's material-system report describes Sankey diagrams with arrow widths proportional to flow quantities. That makes the definition of each quantity consequential. A width can represent a documented transfer, a calculated balance or another approved measure, but the audience should not have to guess which one it is.
Define the arrows before arranging them
Ask the source owner for a table identifying each origin, destination, quantity, unit and period. Include return or recirculating movements where they are part of the approved account. A diagram that looks like a simple left-to-right journey may not preserve a system that sends material back for another stage.
Consider a hypothetical packaging supplier explaining deliveries and returns. One arrow for items sent out and another for items returned describes gross movements. A single arrow for the difference answers a different question. Neither representation should be chosen merely because it produces a cleaner composition.
If the film uses a net figure, label it as a balance and explain what has been combined. Do not animate it as though that exact quantity physically travelled along one route. Arithmetic cancellation and physical transport are different kinds of information.
Keep recirculation from becoming new supply
A return loop can pass through the same processing stage more than once. If the animation treats every pass as a new external input, viewers may overestimate the quantity entering the overall system. Ask the specialist which boundary the totals refer to and how repeated movement should be described.
The film does not need a complete operational model. It needs enough context to prevent the selected flow from being counted twice in the viewer's mental picture. A clearly identified system boundary and a restrained return path can be more useful than a dense network of animated particles.
Avoid making particle speed carry a second quantity unless that meaning is explicitly defined. The arrow width may already represent the approved flow amount. Faster movement can imply higher throughput or shorter travel time without either being part of the evidence.
Review the totals with the flow owner
Ask the reviewer to trace the featured stream through the finished sequence. At each split or return, can they identify what the width represents and which total it contributes to? A visually smooth merge should not conceal a change of unit or reporting period.
When a shorter version removes a return branch, reconsider the headline and total. The original claim may no longer be understandable from the remaining diagram. Simplification should preserve the accounting question, not only the most attractive path.
Bring an approved flow table to Live Images when scoping this kind of explanation. The production can clarify movements and balances while leaving system measurement and reconciliation with the responsible technical team.
Prepared with AI assistance for Live Images. Planning guidance is general; suitability and production scope must be agreed for your project.