The company designed a processing board that could take inputs from digital cameras, high-end GPS units, and inertial sensors, and then integrate data from those systems so that the camera images were coded with positional data.
But they still need to manually check and correct maps.
Yet satellites and algorithms only get you so far. Google employs a small army of human operators (they won’t say exactly how many) to manually check and correct the maps using an in-house program called Atlas.
100 hours are uploaded every minute. 1440 minutes in a day, so 144,000 hours per day. Divide this into 3 shifts, will give you 6,000 man-hours. So Google will need at least 18,000-20,000 people to check YouTube uploads at the current rate.
What defines terror? The message? The guns it contains? How would you draw a line, other than "I'll know it when I see it" for these people to follow?