Same Segment Navigation Problems

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Re: Same Segment Navigation Problems

Postby CBenson » Sun Aug 04, 2013 12:54 pm

Very interesting. This is consistent with this example that I asked about some time ago but never received an answer.
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Same Segment Navigation Problems

Postby kentsmith9 » Sun Aug 04, 2013 6:31 am

I found a problem with navigation from and to the same single segment. While this may not be too common, it might be leading to other higher level problems based on what I discovered.

This first one appears to be unrelated to all the others below, but I thought it was curious enough and could be related based on what is causing the examples after this one.

User is routed the long way around a square (three sides of square) that clearly would have been faster keeping on the second to last segment, going straight (one side of square) and making a left.
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These next routing errors all appear to be an issue of Waze unable to properly calculate the route when the start and end address are on the same segment and there is no other segment crossed before the destination would be reached.

It is hard to see in this example, but the starting house is north of the destination. The route heads south, but skips the destination and circles left on Wingate and left again back to Tanglewood. It then passes the point of origin and finally ends at the destination. It passes both of them twice. Note the Navigation Script does not show Wingate.
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This example is the same as the prior example above with the same circular routing paste the destination twice. When the starting address is just slightly east of this current destination on Brooktree (not pictured here), the route starts east and stops at the destination without passing it. Note that route would cross a different segment before it reached the destination, which was not the case when headed west from the origin. Also note the Navigation Script does not show Alameda Dr.
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To better see the "same segment routing error" I picked a road with many houses and multiple junctions on either side of the base segment. First 2 examples are routing from and two the one segment. Note there is no other route around the neighborhood to get back to these points, so Waze forces u-turns at the end of the segments. But maybe not. Look at the curved purple line not following the street.
Start and destination are on the same segment. Note how the tracking from the one end of the segment to the other does not actually follow the road itself. It looks like Waze considers the two endpoints as continuations of themselves; like a wormhole you exit one end and appear at the other side.
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Reversing the start and end addresses produces the same results and the same wormhole. When I placed the destination west of the origin (not pictured) it produced the same circular routing passing the destination, looping around through the wormhole and back past the origin again to finally hit the destination the second time.
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Now when we route to an address off of the segment of the origin, the direction of travel is direct in both cases. The route does not assume the vehicle is turned one way or another. It seems to turn the vehicle in the direction that best meets the routing needs.

The destination is on a separate segment and routing heads west directly to destination.
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The destination is on a separate segment to the east, and routing heads directly east to the destination from the same origin as before, but headed the opposite direction now.
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Thinking back to the Navigation Script missing some of the roads on the route in the above examples and the Arbor Dr. examples showing that wormhole effect, I looked for something that would better show what is happening.
Gray Fox Cir is linked to two other segments creating a loop with three segments total. However when the start and end destinations are on the same segment, Waze assumes the two ends are continuations and assumes you can route along that wormhole instead of driving on the two segments that should have been very easy for the navigation engine to see.
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  • Same segment routing appears to assume you can leap from one end to the other of a segment as if they are a loop.
  • For same segment routing for some reason it first computes the closest of the two ends of the segment relative to the origin and routes to that end point first.
  • Because routing thinks the two end are connected it can continue on the segment until it hits the destination. Sometimes that means it will pass the origin again.
  • When not routing to the same segment, it properly assesses the correct end of the segment closer to the destination.
  • The client app itself likely adds assumed direction of current travel when calculating the route. I would doubt the Live Map has any knowledge of current direction of travel except when on a one-way street.
  • I am assuming all of the above example behave the same in the client app, but I have not tested any of these yet.
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