JB: Trolley Shot Tracking & Overhead Signage Replacement

As the title of our production is 'Aisle 4', it was important that we ensured continuity throughout our opening sequence.
As we wanted a freezer aisle as our location, we were only able to use the 8th aisle in Tesco. This meant that we would have to replace the numbering in post-production, as it was not practical to manually change the signage in the store whilst there.

Luckily, only one of our shots featured the overhead signage that we wanted to change, and as we had affixed the GoPro to the inside of the trolley for this shot, the framing does not change throughout the footage. This meant that it would be relatively easy to reapply the bars of the trolley after replacing the numbering.


So that we did not have to regularly re-export our footage, I used Adobe's Dynamic Link feature to replace our GoPro shot with an After Effects Composition onto which I could make our alterations.

After exporting a still from the start of the footage which includes the whole '8' section of the signage, I replaced the number in Photoshop matching the perspective as best as possible in Adobe's Myriad Pro font - which matched the style used by Tesco. I could then crop this still to isolate it to just the number, and reimport it into After Effects.
Using the 'Track Motion' tool, I chose two points on the signage that remain visible throughout the entire sequence in order to track scale, perspective and position across our clip. This tracking data was then applied to a null layer, to which the number was parented. As a result, our new number followed the original sign accurately!

After Effects Composition - with tracked motion.

• Tweet
• Like It
• Google +