At an event today in San Francisco, Google made a predicted announcement: 3D maps—not just little buildings drawn with perspective, but genuinely detailed 3D structures and topography—are coming to Google’s maps app. After Google reminisced about how far it has come since purchasing maps startup Keyhole half a decade ago, the company introduced an offline maps feature that will surely please its more adventurous users.

But Google could face real competition for the first time in half a decade, and some of what it announced today will be judged according to how well Google Maps will stand up to that. After all, millions of iPhone users may soon be giving their search data to Google’s “thermonuclear” antagonist, Apple.

Arriving in the third dimension

Peter Birch, product manager of Google Earth, introduced photorealistic 3D imagery in Google maps for both Android and iOS devices. The feature has been around since 2005, but never really succeeded at giving a consistent 3D image, due to a disparity between synthetic and real-life images.

Google detailed how it is planning on bringing better 3D maps: “This starts with planes equipped with custom Google-designed imaging systems, positioned in coordinates,” Birch explained. Then “planes are flown in a tightly controlled area” to get every possibly angle of a building or storefront.

When pressed on the planes, Google Vice President of Engineering Brian McClendon said that the company "has a fleet of planes that fly exclusively for Google.” Drones, however, were not yet in the picture according to McClendon.

From there, Google’s aerial images undergo stereo-photogrammetry—reconstruction of the various images taken from all different directions. Google finds the best color for each pixel on the model to generate a textured 3D mesh.

It’s unclear how quickly this will be rolled out to users, but Brian McClendon admits that bringing the power of 3D in Javascript to devices everywhere will be a challenge for the search giant. “We have to package up that information in a way that is efficient to store and serve up to people anywhere in the world,” Birch said.

Still, the demo promised some very cool future applications. Users interact with the models by twisting their fingers. “The consistency really gives you the illusion that you’re just flying over the city, almost as if you’re in your own personal helicopter,” Birch commented. To get the most out of 3D maps, Google will also include a “Tour Guide” application that will help users explore areas of interest in 3D.

Part of the new 3D project will involve making better indoor maps, pinpointing locations in buildings as much as on a 2D plane.

Privacy may be an issue for the new 3D maps, but Google could get by on the fact that rather than publishing actual images as it does in Street View, the company is making a model from composite images. That doesn’t mean Google doesn't have new plans for imaging the world. Luc Vincent, Google’s director behind Street View, showed off a backpack mounted with Street View technology that will be able to get into new hard-to-reach areas (and cause privacy concerns).

Ignoring a possible slight from Apple

Since MapQuest, Google's competitors in the maps department have been few and far between. OpenStreetMaps is a good alternative, but it isn’t quite as full-featured as Google’s product. Yahoo Maps is a joke. But on the eve of WWDC, the biggest question for Google is how it would handle the loss of Apple’s vote of confidence.

And part of this announcement might be to beat Apple to the punch. In 2011, Apple “snapped up C3 Technologies, a Saab spin-off that had developed automated 3D mapping algorithms and had begun building a database of 3D maps of the entire globe,” Ars Apple Editor Chris Foresman wrote.

The Wall Street Journal confirmed with sources that Apple will likely ditch Google maps for an in-house maps product in iOS 6. That is expected to be announced at WWDC this June. "In the short term, Google will lose some ad revenue and miss out on data about what local businesses people are searching for—which it uses to pitch retailers on buying certain ads," WSJ noted. "Longer term, it is likely to hurt Google's ability to generate map-related revenue, according to former Google employees."

When pressed on Google’s reaction to Apple’s slight, Brian McClendon only affirmed that their years of product development made Google Maps stronger than any other maps product.

Your Android is a paper map

Google also announced offline maps for Android. Rita Chen, product manager for Google Maps, demoed the new feature, which seems genuinely cool. First, you navigate to the place you plan to visit and select “make available offline.” When you select an area, it will estimate the file size of the map depending on the size of the area you choose. If you still have WiFi or Bluetooth in the area, you will see a little blue dot on the map, denoting where you are.

The best part: as you zoom in on an offline map, the map remains clear, not fuzzy, even as you go down to street level. So you can finally throw away that old Thomas Guide.