AI video generators thrive on specificity, but screenplay sluglines were written for human crews, not algorithms. When the same slugline produces shifting lighting and locations shot after shot, the problem isnt the model--it's the prompt translation. This post explains how to turn a vague scene heading into a consistent light-and-location anchor for every frame.

Introduction

Screenplay sluglines open every scene with a simple formula: interior or exterior, location, and time of day. To a human crew, thats enough. A gaffer, a location scout, and a director of photography each read the heading and fill in the rest from experience, reference photos, and the call sheet. An AI video model has none of that context. It generates entirely from the words in the prompt, and when the prompt is just a standard slugline, every shot can look like a different scene.

What Happened

Early in my AI animation project, I generated three shots from a single slugline: EXT. FOREST - DAY. The wide shot bathed the scene in golden hour light. The insert showed flat midday sun. The close-up read like dusk. All three came from the same line of script. The model wasnt confused--the prompt was. The standard slugline format is deliberately vague so a human team can decide the actual lighting on set. For an AI, that vagueness means it invents the lighting from scratch every time, and it invents something different each time.

Why This Matters

When a scene spans multiple shots, inconsistent lighting and location details make the final video feel like several different scenes stitched together. Production costs rise when every mismatch requires a regeneration or a costly reshoot. The fix isnt a better model--its writing down what DAY or FOREST actually means before generating the first frame, then reusing that definition for every shot in the scene.

Key Takeaways

  • Expand each slugline into a light-and-location card before the first generation, not after mismatches appear.
  • Turn DAY into a specific light description: low sun camera-left, hard edge light through foliage, warm color temperature.
  • Turn FOREST into fixed nouns you reuse: moss-covered stone path, birch trunks, low fog at ankle height.
  • Treat the card as locked for the entire scene. If the story needs changing light, thats a new slugline and a new card.
  • This discipline mirrors what good editors already do with shot lists and continuity notes--just applied one step earlier, at the point where the slugline gets read.

Conclusion

You dont need special software to start. Any tool that outputs a standard slugline--Final Draft, Scrivener, Celtx, or even plain text--works. The conversion happens after the slugline exists, not inside the writing app. Start reading your headings the way a gaffer would, before the first generation, not after the third mismatch. Your future self--and your budget--will thank you.