Lee Gomes writes in Slate The autonomous Google car may never actually happen.
For starters, the Google car was able to do so much more than its predecessors in large part because the company had the resources to do something no other robotic car research project ever could: develop an ingenious but extremely expensive mapping system. These maps contain the exact three-dimensional location of streetlights, stop signs, crosswalks, lane markings, and every other crucial aspect of a roadway.
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…the maps necessary for the Google car are an order of magnitude more complicated [than Google Maps].
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To create them, a dedicated vehicle outfitted with a bank of sensors first makes repeated passes scanning the roadway to be mapped. The data is [sic] then downloaded, with every square foot of the landscape pored over by both humans and computers to make sure that all-important real-world objects have been captured. This complete map gets loaded into the car’s memory before a journey, and because it knows from the map about the location of many stationary objects, it’s computer—essentially a generic PC running Ubuntu Linux—can devote more of its energies to tracking moving objects, like other cars.