In-depth Review: Apple's iOS 6 Maps & the alternatives 2: Maps and visualizations
Views from the street
Sometimes a standard map (even with 3D models of buildings) isn't enough to visualize a location or find your bearings. In some cases, an abstract map representation is less useful than seeing an actual photograph of what an area looks like, taken either from the street or from overhead. In many cases, both types of imagery can be used together to orient oneself or navigate a complex intersection.
In iOS 5, Apple provided both "satellite" images (often actually taken by airplanes) and Street View vantage points for specific locations, both from Google servers. Google has spent years collecting Street View panoramas every few feet along most major roads.
While no longer presented in iOS 6 Maps, Google's Street View is still accessible to iOS 6 users, both via third party apps and from Google's own web app. Rather than attempting to duplicate Google's Street View, Apple's new Maps provide a different kind of photorealistic perspective.
3D Satellite views
In iOS 6, Apple presents its own "top down" satellite images. In place of street level views, Apple developed technology (based on its acquisition of C3) to take existing satellite data and build 3D topographical images out of it.
When you turn on "3D" with Satellite images selected, you actually get a topographical map, with a greater range of perspective possible compared to the Standard road map. This works pretty well for landscapes, making Apple's 3D Satellite views an interesting way to compare the flat perspective standard view with how the earth actually looks (below).
Using this sophisticated software to create a 3D perspective for existing satellite images technically works anywhere, even in North Korea.
In cities however, Apple's automated 3D satellite perspective images appear relatively flat, just like the flat satellite images Google supplies in its Android app when looking at street perspectives. In some places, Apple's 3D rendering software depicts structures or landscapes incorrectly.
3D Flyover views
To improve upon this, Apple acquired C3, the company Nokia partnered with to deliver its experimental Maps 3D project. Similar in some respects to Google Earth, the technology builds detailed 3D maps of buildings and other man-made structures, a feature Apple brands "Flyover." Unlike its competitors, Apple integrated its Flyover feature directly into the mobile Maps app as a feature of the Satellite layer.
Turn on satellite images and you can activate Flyover (anywhere that "3D" is replaced with Apple's buildings icon) to get an even better real-world depiction of what things look like at closer zoom levels. This was also never supported in iOS 5 Maps.
While Flyover does a good job of automatically rendering mountain landscapes in perspective, it can't automatically build photorealistic models of cities, bridges and other small-scale man-made structures. Apple has to manually build models of cities, and this currently limited primarily to US cities (although support for Flyover is quickly spreading).
Apple's Flyover works in places its "3D Buildings in Navigation" does not, such as Portland, Oregon, which currently lacks grey 3D models in Standard view, but does have hand-drafted, photorealistic buildings in Flyover (below).
Flyover vs Google Earth, Nokia Maps 3D
Google Earth and Nokia's Maps 3D provide similar views to Apple's Flyover, but only Earth is available on iOS. Nokia offers its beta Maps 3D in 25 cities, but the feature is limited to desktop browsers because it requires a special plugin to work. Nokia also has a slower, plugin-free version but it isn't supported on iOS either; both work from the desktop version of Safari.
While based on the same underlying technology as Flyover, Nokia's Maps 3D are neither as fast and efficient nor as easy to navigate as Apple's multitouch Flyover. Even in the few cities where it has modeled buildings, Nokia's Maps 3D representations are a lot less detailed.
Google Earth offers significantly lower quality renderings and appears to be based on more outdated satellite images compared to Apple's Flyover. Google only supports 3D buildings in a few cities. The product was originally intended to be a cool way to visualize the planet from pieced together aerial photographs, rather than being a functional tool for navigating around, so it can be difficult to zoom in for street level views.
While Apple's Flyover images were a particular subject of complaint for Apple's new iOS 6 Maps, neither Nokia nor Google offer photorealistic 3D city models integrated their mobile maps products for Android or Windows Mobile, and both suffer from significant visual glitches, even in areas where they are supposed to be complete.