Want to know exactly how many people saw your ad on TV? Want dynamic insertion? The answer has long been "tough luck." But now it's possible … in Kansas City.

Adweek has learned that Google will be rolling out a TV ad-tracking system similar to the technology used to measure ad views online, giving the company a more accurate idea of how many people are watching the ad inventory it sells in Kansas City than traditional panel measurement ever could.

This is a big deal: TV measurement has been changing rapidly in the past few years, but the traditional gross ratings point, which relies on a panel of Nielsen viewers small enough to create problems for networks without multimillion-viewer bases, is still the industry standard. Relatively few households have Nielsen boxes; every household with Google Fiber, obviously, has a Google Fiber box. And that box can put the ad in whenever it's timely, and tell the client about it.

"Fiber TV ads will be digitally delivered in real time and can be matched based on geography, the type of program being shown (sports, news, etc.), or viewing history," the company explains in a blog post set to go live this afternoon.

"Like digital ads, advertisers will only pay for ads that have been shown, and can limit the number of times an ad is shown to a given TV. We're excited to see how this test progresses, and we're looking forward to hearing from local businesses and viewers along the way."

Viewers can opt out of being shown ads based on their viewing history, the company says.

The ads will show during existing ad breaks in much the same way that local buyers like car dealerships or restaurants can buy airtime from a national cable provider in a specific market (Time Warner Cable has specific advertising time reserved in Cincinnati for people who just want to advertise there, for example). But these ads will show on both live TV and DVRed programs—in other words, if you save Sunday's Walking Dead until Wednesday, you might get ads for a sale at the Oak Park Mall that starts on Thursday.

"The tracking at this point is pretty unsophisticated," says a source familiar with the deal, explaining that Google is trying to be extra cautious with user privacy on this initiative. Advertisers will pay based on the number of times the ad was shown—the people who watched aren't fed back into a database and matched up by data and purchaser info. But direct, one-to-one measurement of viewers is still a giant step forward on television.