Author Topic: Planner trackglitch detector  (Read 238 times)

Offline 0709

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Planner trackglitch detector
« on: October 06, 2021, 19:06:13 »
Hi Menion.

The trackglitch indicator by the Locus_app_BRouter (offline) planner is sure a very usefull tool.
The indication is nice and clear with both circle indication and the relevant (short) trackglitch section.
But when  using Locus_app_GH online some trackglitches than are surprisingly not indicated ?

Good to know, why that happens ?
As GH generates a simplified track there are not always exact 180° overlap track backfolds.
Anyway the 180° U-turns by GH web router are reported by the Locus rtePointAction>12
In the commands list see nr 12,  the non directional U-turn. https://t.ly/8cn8
(As Locus tool detects only the 180° overlapping track folds so generates no warning indication)

In attachment file by GH web inclusive U-turn.

Q:
Why Locus_Brouter_GraphHopper should not attach the usefull 180° U-turn command ?
a. When indeed this is a correctly planned traject inclusive u-turn so not be corrected ? 
b. A "forgotten" undiscovered so uncorrected trackglitch still can be detected out of the planner screen also in the turn command list.
c. It would prevent even more that some track glitches (GH track simplify) still escape the alert and attention.


In any case, there will always be (inattentive) tracks shared including turnglitches and thus false annoying turn commands.  If there is U-turn support, you can still "accentuate" suspicious u-turn elements with a circle, also later in the normal map display used for navigation. The standard turns get the usual discrete "blue" small dot. And the U-turns get that extra "alert circle". In this case, they will not escape special attention so quickly.

IMO, u-turns in a track and this in all u-turn variants and certainly the 180° version are always a bit strange or special. Often, u-turns are undesirable but this is clearly not always the case. Indicating u-turns as 'special' on the navigation map and thus calling attention to them does not mean that they MUST necessarily disappear.

In attached picture.
The 180° U-turn Icon !  Please apply this in Locus map !
By a most simple U without any Left nor Right tail arrow .
Small arrow is reserved to indicate a Left or Right U-turn !


General trackglitch prevention by sharing compact gpx (rte)route files.
Reference (rtept)routepoints should NEVER be shared by routepoint positons (turns) on top of street junctions/corners. 
As at exchanges with other program/routers even the slightest map difference than generates mini trackglitches.


« Last Edit: October 16, 2021, 09:52:47 by 0709 »
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Offline Menion

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Re: Planner trackglitch detector
« Reply #1 on: October 07, 2021, 15:02:17 »
Hi Willy,
hmm this simplification is quite stupid, thanks for the info about it.

You wrote "If there is U-turn support, you can still "accentuate" suspicious u-turn elements with a circle, also later in the normal map display used for navigation. The standard turns get the usual discrete "blue" small dot. And the U-turns get that extra "alert circle". In this case, they will not escape special attention so quickly." > in the app already is U-turn support. Question is if problem you found is rare or happens really often. If it is rare, then I do not think it is necessary to solve. GraphHopper is no longer a primary app router engine and this small feature is a not a core feature ...
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Offline 0709

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Re: Planner trackglitch detector
« Reply #2 on: October 09, 2021, 09:34:23 »
Quote
In the app already is U-turn support
Unfortunately this is only half true :-((
Locus map indeed supports 180° U-turn commands if imported but sadly does not generate any, not even by Locus_GraphHopper online although GH provides this info by default.

It is absolutely useful that Locus would support & generate the 180° U-turn commands. Not that many people like them, but so that they can be avoided as much as possible, except for some explicitly planned ones. An indication on the map where exactly these commands are so located is quite useful information. So be able to indicate U-turns not only in the Locus planner screen but even usefully be alerted for U-turns in the standard operational map screen makes Locus map even more performant to tackle this very annoying trackglitch & U-turn problem.

(The RouteYou planner actually is the only one that attaches 180° U-turns in the Locus gpx export file)

Quote
Question is if problem you found is rare or happens really often.
Well Sir, I don't really know how frequently this happens.
As I usually place the Planner Points quite correctly ;-)
I discovered this by a (rarely) false positioned shaping point click using GH.

Simplified tracks as generated by the Locus compatible routers.

1. Reference Locus_GraphHopper planner (internal): Simplified track, NO U-turns.
2. Plotaroute web planner (gpx trk_navwpt) : Simplified track, NO U-turns.
    Plotaroute_trackglitch_control.gpx
3. RouteYou web planner (gpx trk_navtrkpt) : Simplified track, PLUS U-turns.
    routeyou-trackglitch_control_zele-locusmap.gpx

Note: Generates 3x an identical track result, seems all use GH ;-)
« Last Edit: October 09, 2021, 21:44:12 by 0709 »
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