To the people who knew about it, great! But for all those who learn new things about sport every day, this is for you. The advertisements we see on the small boards around a football stadium on television can be filtered according to the country and ads. How is it done?
This technology is called the virtual replacement perimeter technology.
The Twitter user @UltraLinx made the observation, here is how he explained how the technology works.
The camera is placed on a “virtual head” which reads the positioning and alignment data. The lens of that camera is calibrated with the camera body and sensor, along with the software, so that the virtual software can be adjusted for any variance for offset off “zero” when the camera was mounted.
Think of a virtual 3D box, and they just tell the computer where to put everything relative to the camera. Data is fed from the camera to a computer running the virtual software. After the calibration, the virtual operator will load in the graphics they have been given, created to whatever specifications. They then use various keys to mask out what they want and don’t want the virtual graphics to appear on.
This same technology is not only used to make virtual billboards, but distance lines (e.g. horse racing), stat overlays, on-ground logos, and images…up to and including whole studios.
Have a look at companies like Broadcast Virtual, Statcast3D, and Zero Density for more examples. Even MLB Advanced Media does some amazing stuff. As others have pointed out, the top left is what people in the stadium see, this is not green-screen, just a key overlay. You can tell this by the shutter speed between the camera and the signage being different.
This is one of the ways of using the technology and doing, there are multiple other methods to use this technology. Technology plays an important role in numerous aspects of sports, and now its causing a paradigm shift in the world of sports advertising.