Battle On

So I found one of the coolest marketing ploys I've seen in a while during one of my Metro Red Line trips back from work. I usually kill time aboard the Los Angeles subway train by looking aimlessly out the window. I was doing just that the other day when all of a sudden the image of the Emile Hirsch as the Wachowski's Speed Racer popped up on the glass. I jerked back in surprise but I didn't dare look away. I knew WHAT I was looking at but not HOW it was occurring. Then I realized the image was actually moving. Like a motion picture. Then I realized the image wasn't being holographically projected onto the window but was instead a series of images, most likely LCD screens, attached to the concrete tunnel wall. I looked at the other windows on my side and noticed the same thing. What was happening was the illusion of movement much like the way a zoetrope works. A rapid succession of images moves in a horizontal direction while the viewer looks through a viewing hole, in this case the window, and only sees one image at a time.

Now here's a math problem for you: The Speed Racer advertisement is located between the Universal City and Hollywood/Highland stops and lasts for about 10 seconds. That distance takes about three to four minutes to cover by the train while it's traveling at about 60 to 70 miles per hour. Each screen is about two feet wide and attached next to another screen. The illusion of movement occurs with viewing 24 frames per second. How many screens are attached to the wall and how long do they collectively span in the tunnel? Most importanly, how much would this marketing trick cost?

Here's another modern example of a zoetrope: