On 9/18/2011 1:34 PM, Anthony wrote:
On Sun, Sep 18, 2011 at 1:21 PM, Nathan Edgars II<nerou...@gmail.com> wrote:
On 9/18/2011 1:18 PM, Anthony wrote:
http://www.pocketgpsworld.com/reviews/tomtom-v8/v8_lane_assist_northwest2_speed_alert.jpg
Do you think Garmin is mapping every lane as a separate way here? I
don't think they are, or that they should. I think if I were going to
do it, I'd map this as one way up to the theoretical gore point, and
then as two ways after the theoretical gore point. I wouldn't use
five ways.
It's simple on a motorway. But, for a simple example on a surface road, how
do you know where the straight lanes go if there are 3 lanes after an
intersection but 2 before?
Depends on what data you have. If you have lane width information,
then it's easy to figure this out. If you don't, then you can't
figure this out. If all lanes are parallel, you certainly don't need
a way for every lane, though.
But why is this important in the first place?
If you have two intersections in quick succession, and are turning at
the second, you want to know which lane to be in at the first. That is,
given that we want this sort of thing in the first place.
And actually, even on a motorway, what if it's 4 lanes to a split of 2 and
3? The assumption is that the second lane from the left can be used to exit,
but it's possible that only the leftmost lane is available, and a second
lane begins on the ramp right at the gore. Or perhaps there's a short
segment of 5 lanes before the split - how do you know which side the new
lane forms on?
This can be determined by the geometry of the ways, which are mapped
at the center.
No they're not.
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