The tech behind Google's Street View

I spent a good part of yesterday tooling around with the new Google Maps Street View feature. It's one of those Web services that just works. Here at CNET, we're also centrally located in one of the few cities (San Francisco) to have nearly all of its main thoroughfares Street View-enabled. The data for four of the five Street View-enabled cities comes from a company called Immersive Media. In addition to these interactive 3D pictures, they use the same technology for videos. Both use an 11-lens camera called Dodeca 2360 that captures an immensely large surface area of images at a very high resolution. This camera is mounted on top of a moving vehicle that both records video and geodata simultaneously. What we're seeing on Street View are image stills from that video, which is how you're able to get a new shot from nearly every point on a recorded route.

One of my big questions whenever these photographic services come out, is how often the imagery gets updated. I had a meeting earlier in the week with the folks from DigitalGlobe, who provide satellite imagery for Google Earth, and several other private and commercial services. They explained that the aerial and satellite maps we see on these services are generally completely redone every year, with the more populated areas getting more frequent flyovers and subsequent refreshes. In comparison, the level of detail and proportionate work that goes into the tech behind Street View is very resource-intensive. According to Immersive Media, they're typically on the road capturing imagery and data 46 hours a day using multiple vehicles with the mounted cameras.

Daniel Terdiman had an interesting post yesterday about some of the minute details these images have captured, and the inherent security issues. Wired is currently running a best finds contest, and earlier today Mashable posted several user-submitted findings that contain some of the more interesting photos found on the service.

One of the discoveries I've made is a relatively easy way to tell how old these photos are: gas prices. In the case of the Street View photo that's at my nearest station, they're selling a gallon of regular for $2.67--this was obviously taken in better times, and using this site we can pin it down to around August of last year. In other cases, the camera might have captured an electronic sign on a bank, or billboard.

While Street View is really neat, what I'd like to see more than anything is using these photos to enhance driving directions, as it's often easier to spot an exit or street to turn on based on what it looks like rather than rely on tiny little green signs. Considering that the data has come from video footage, a quick highlight reel of turns wouldn't be so bad either.