MapBox Rethinks the Satellite-Based Map, with Beautiful Results

By Wesley Fenlon

What could you do with five billion pixels?

The Google Maps update announced at this week's Google I/O Conference integrates the satellite view of Google Earth. It's 3D! It looks great! Of course, if you look closely, Google Maps' images will still have plenty of imperfections. At the street view level, photos are often blurry or awkwardly stitched together. That's the price we pay for total coverage, and the good news is that quality is constantly improving.

Making smarter maps, with more usable data, is Google's primary goal. The mission of another mapping service, named MapBox, is something very different. MapBox wants to make their maps gorgeous. The best looking on the web. And they're doing a pretty damn good job.

Image credit: Mapbox

Wired recently wrote a behind-the-scenes look at MapBox, a small team of about 30 using open mapping data to build a prettier, if not better, map. Their service is currently used on Foursquare and Evernote, and they've had other partners in the past. While MapBox isn't as big as Google Maps or Nokia Maps, they're gaining a foothold, and their use of totally open data allows for a lot of flexibility. The best part of the story is how they're getting that data, and what they're doing with it, which is where MapBox really differs from Google Maps.

MapBox's satellite imagery comes from NASA's LANCE-MODIS system, which is public domain. Here's challenge one, as Wired explains:

“ 'For the new release we’re processing two years of imagery, captured from January 1, 2011 through December 31, 2012,' says [MapBox's Charlie] Loyd, 'this amounts to over 339,000 16-megapixel+ satellite images, totaling more than 5,687,476,224,000 pixels. We boil these down to a mere 5 billion or so.'

"The first problem is even getting the data. It’s all available in the public domain, but just transferring it over to MapBox’s servers was a major task because of the volume. To do this render, they needed to download two thirds of a terabyte of compressed data. 'We’ve got 30 to 40 servers pulling down data from NASA,' says [data analyst] Herwig. 'We called them up and said, ‘hey we’re going to hit you hard, what’s the best way we can do it for you?' "

Dealing with a mere five billion pixels sounds like a huge challenge, but of course that's nothing new to companies that have mapped the entire Earth. Typically, the satellite imagery would be scanned, and the brightest, least-cloudy images would be chosen because they give the clearest view of a region. There's an obvious issue with this technique: images won't match up. Two locations side-by-side could be represented by photographs taken months or seasons apart.

MapBox wants a seamless, beautiful map. That takes a different approach.

MapBox "takes all the images it has of an area and stacks them on top of each other," writes Wired. "Then, it reorders each column of pixels in the stack based on how cloudy it thinks it is. 'We do that for every pixel in the world,' says Loyd.

"Once MapBox has reordered the pixels, it takes the average of the least cloudy ones, and that average becomes the canonical pixel for that particular spot on the map. The scale is dizzying. Loyd says that when he and his team were about 40 percent of the way through the job, he calculated that if they printed out their work to that point, it’d cover 2 acres of land at 300dpi.

"MapBox has to pull some other tricks too. The color of the landscape changes throughout the year as summer green leaves turn to oranges in the fall, then snow falls in the winter, then new growth returns in the spring. Average all that together and you’d get a muddy brown. So the team uses some techniques to ensure that they’re capturing peak growth, which is May/June in the northern hemisphere and December/January in the southern."

Photo credit: Mapbox

The final product: a seamless, eternal summer on Earth, without a cloud in the sky. It's not necessarily the most realistic representation of summer, but compare Google Maps and MapBox and it's hard to miss how vivid the latter's satellite view is. Google's moving forward with some seriously smart data usage, but MapBox is focusing on something digital maps have sometimes had trouble with--simply making them nice to look at.