GPS logs can help ensure that Smart Directions
match what someone with local knowledge would do in the same circumstances.
One-way streets and turn restrictions are often obscured when you map raw GPS points,
but this animation shows a series of steps that we take to get a clearer view of what is happening
on each street and at each corner:
Start with the raw GPS points.
The ones shown here come from a collection released by Uber.
Tighten up the GPS noise by snapping together points from different vehicles traveling in the same direction.
Offset the tracks by 90 degrees from the direction of travel to highlight the directional split on each street.
Connect lines around the corners to make right turns visible.
Average together a series of successive points from each vehicle to pull left turns back between the carriageways and make them visible through the middle of the intersection.
The stages of cleaning up GPS logs in San Francisco
Here’s another image showing the many possible looping turns between the one-way streets in a larger area of downtown San Francisco.
Looping turns on downtown San Francisco’s one-way streets