Ric Forster - Writer & Filmmaker

Thinking Straight VFX: Motion tracking and inserting digital flags

An update on the post production on my short film Thinking Straight – the edit is pretty much locked and I’m just tidying up the sound mix, along with creating a few little visual effects…


The final shot calls for Dilly and Sam to head off holding hands down Canal Street – the hub of Manchester’s lgbt nightlife.


There’s usually a number of rainbow flags on the street’s lampposts, but for some reason these were missing on the day that we filmed there. It was a shame as it’s really important to the story of the film that the girls walk down the iconic road, where they’re finally “out” together.


Here’s a still from the original scene:


I decided to take a shot at adding in the flags in post.


Starting in Photoshop, I added in some photos of flags on top of the street image. The shot contains quite a bit of movement; a pan and jib up. The challenge was getting the flags to move in sync with action on screen. To do this, I used match-moving software to track hundreds of tiny details in the scene, creating a path of movement that the flags would be able to follow.


Here’s the final result:


Not perfect, not very flashy – but I think hopefully it does the job.

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