Elevation - bringing the Seagull to Australia
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Following the initiative from Waze on Sun Jun 08, 2014 2:44 pm we finally decided (after some open questions answered and possible negative effects on routing have been taken care of by Waze) to adopt the policy for setting the elevation levels. The start of application of the new rules with the very first Australian Map raid (8 Nov 2015 in Melbourne)
Now let's get into it: The reason for this change of heart is coming from Waze side and it's closely related to the redesign of the livemap that happened last year, where there is a distinction between level roads, bridges and tunnels. This visualisation is also planned to be implemented in the client, once we are satisfied with the representation in the livemap.
You sure wonder now, what the hack has this got to do with a Seagull? Well it has established as a reference for the new approach to handle elevation mapping for Waze themselves introduced it with an example of a Seagull...and here we go now:
So how should a street level be mapped from now on in Oz? Here are the words from Waze on that:
- If the seagull can fly right under it, it’s a bridge (level greather than 0).
- Unless our seagull is flying underground (why would it?), in which case it’s going in a tunnel (level lower than 0)
- For every other case the road is ground level (level = 0), even if it’s artificially elevated or dug under street level.
You keep following so far? So it's always about the reference to the solid ground directly below the street, no matter of height relative to the surrounding area. No matter, if the road is on an embankment or in a trench, it's always Level 0 = ground. If it's real underground it's level -1, if it's off the ground (seagull can fly right under it without hurting itself!) it's level 1.
So far, so good, but there's more to it:
- We mark bridges with level = +1.
- We only mark a road as level +2 if there’s another bridge (+1) running underneath it.
- Same logic goes for +3 +4 …
- Same logic goes for -2 -3 tunnels…
Well, that's not surprising either, but here comes the big one (at least for the guys who have given some thought on routing issues):
- In many cases we will need to split segments into two or more segments to correctly mark only the right parts of the road as a bridge or a tunnel. (again, this is important for the map’s fidelity and as cues for drivers)
If you can't believe we are now introducing extra junction nodes (for we have been eager to avoid them in the past), just read the para again, because definitely yes, we are doing it from now on.
Waze have looked into possible impacts on routing calculation and routed them out, they choose "to stick to an accurate representation of the map with tight marking of bridges (level greater than 0) and tunnels (level lower than 0)".
So there is just ooooone tiny bit of vital information, regarding tunnels: yes, we want it marked tight, but in case of tunnels not that tight: it is important, that a tunnel segment has GPS lock before and after the tunnel. As we all know, this is impossible once you're in the tunnel so keep the "tight marking" at least 15m BEFORE and AFTER the tunnel and don't forget to tick the Tunnel checkbox for the segment going through the tunnel. But really just for tunnels, in case of bridges Waze want's us definitely to set the additional junction node on the spot (this hase been introduced by a Waze routing dev, so absolutely official and nothing like community or local champs stuff).
Btw, this applies on railroad street type too, we no longer hide them at -5 as we did back in a while...
OK, that's about it, go ahead now, there's a whole continent waiting to be checked and brought up to state of the art.
|due to Wiki is a living media there might be deviating information within the Australian wiki until we all routed it out. Mind the following simple rule: information on elevation on this page beats any contrary statement on another Oz wiki page.|