First off, I’m not much of a baseball fan, and almost never watch it on TV, so this question may seem quite dumb.
Be that as it may, this question is about those display ads you see on the low wall that separates the best spectator seats from the inner part of the playing field. A few years ago, I swear that I heard someone on TV say that the ads you see on a broadcast baseball game are not what you would see there if you were attending the game in person, but are cunningly added to the broadcast signal by the TV station. I can’t remember what show it was, or who said it, but it seemed to me to be a reputable source.
I wasn’t very skeptical of this at the time, but the more I think about it, in retrospect, the more I feel it was a whoosh.
Those ads aren’t really there - you can only see them on TV. In fact, you can only see them from the centre field camera angle. If you watch a few games, you will notice that when that part of the wall is shown by a different camera, you just see a plain green area on the wall where the ad should be.
Some ballparks do have a rotating ad panel behind the plate, and the ads are there no matter what you’re looking at. I’m watching SF @ AZ right now and it appears that the ads are really there.
Some ballparks have a blank green panel behind the plate (or they add a green panel to their rotating ad panel) and a TV station can project an ad on there. It’s basically a realtime green-screen. I believe the technology is called L-VIS. It seems similar to the technology that “projects” a yellow line on an NFL field.
When they first started using L-VIS, it was pretty easy to tell, sometimes the ad shimmied, or it would “project” onto a batter’s uniform if he stood just right at the plate. Later, you could only see a kind of a halo around the batter. Nowadays it’s pretty hard to tell.
The easiest ways to tell are to watch for a camera angle other than the default center-field view- usually that’s the only camera that will show the ad, and sometimes it’ll only show live (as opposed to an instant replay. The other way is to watch the ads themselves. If the Giants are playing in Arizona, and I’m watching my local (SF) broadcast, I know that if the ads I see are for the Arizona Republic and the Diamondbacks ticket office, I’m seeing a “real” ad panel at the park. If the ads are for sfgiants.com and the Santa Cruz Beach Boardwalk, then I know that I’m seeing L-VIS. And you can always watch for a halo effect around the batter when he steps in front of the panel.
Of course, sometimes, like the game I’m watching now, all the ads are for Nissan, McDonalds, and SBC, which are no help at all, though it appears to be a “real” ad panel.
I don’t watch many sports on TV, but this technology has been used extensively during the Sydney and Athens olympics. The flags and names thart appeared on the floor of the swimming pool before each race, for example, were not really there. (This was much more apparent when they did this for track and field events, where it didn’t look nearly as good.)
They also put gold and silver arcs out on the field to show how far the current competitor would have to throw his javeline, shot put, discus or hammer to medal.
Anyhoo, the same technology is being used by the networks to place advertisements.