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The Story Behind Google Earth’s New 3D Cities

I am really impressed with the new 3D imagery on Google Earth. If you haven’t seen it, take a look at cities like Los Angeles, San Francisco, Rome, Portland, Seattle, Avignon, Munich and many more. I got to wondering how on (Google) earth they were doing this. There is no way that someone was sitting at a computer and making individual models of tens of thousands of buildings and trees – 3D models of entire large cities. And in fact they do have a new way of making these city models – automatically.

Previously, if Google wanted to create a 3D model of a city, they had to individually model each building in a program called Google Sketchup, a very simple 3d modeling program. Someone had to painstakingly make the model, then find photographs of the outside of the building and map them onto the sides so it looked like the real building. It was massively time consuming, so Google crowdsourced the job, enlisting thousands of people all over the world to do it, many just hobbyists. The results were spotty and inconsistent. Some looked realistic, others were cartoony. The lighting was uneven. Placement of the buildings was often inaccurate, and not all buildings were modeled – often there were just a few buildings popping up in the middle of an otherwise flat city.

Now they’ve announced a new technique for creating 3D city models, called stereophotogrammetry. They now have, believe it or not, a fleet of planes that fly over cities, sort of like a flying version of their street view cars! Cameras are mounted on the planes that shoot high-resolution images at 45 degree angles, from directly overhead, and from multiple directions. The stereophotogrammetry process then automatically compares the various aerial photos to calculate the geometry of the buildings and trees and landmarks and create a textured 3D mesh of the entire city, including not only the buildings, but also trees, plants and even cars and trucks!

The result is a remarkably accurate 3D model of the entire city and its surrounding area, complete with accurate photographic textures. All of the buildings and structures are accurately placed, and the quality, lighting and shadows are consistent over the entire model. And because it’s automatic, it can be rapidly rolled out to cover large areas. Google’s Peter Birch expects this new technology to cover “communities of over 300 million people” by the end of the year.

Here is a gallery of some of these amazing images. But explore these cities yourself, you will be amazed.

AvignonMannheimMunichRancho Palos VerdesRomeRomeSan FranciscoSeal RocksSeattleWilshire Blvd.

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