[mkgmap-dev] dissapearing roads

Mon Mar 24 17:27:54 GMT 2014

ok, thanks for any solution :)

best regards

Michal Rogala


2014-03-24 5:32 GMT+01:00 Gerd Petermann <gpetermann_muenchen at hotmail.com>:

>  Hi Michal,
>
> okay, now I was able to reproduce it, don't know what I did wrong before,
> the problem occurs also with the default style, typically for motorways
> in the overview map.
>
> This is what happens:
> You have two ways with equal attributes like name, type etc.
> Both ways share one or more points, but they are going in opposite
> directions, but they share not all points.
> The LineMergeFilter doesn't care about direction and merges the two lines.
> This creates a line with a spike,
> Simple case:
> Line1 : a->b->c
> Line2:       b<-c
> Result after merge:  a,b,c,b
> The DouglasPeuckerFilter removes the spike between a and the last b
> when the error is within the tolerance, so the remaining line is  a->b
> instead
> of a->c
>
> In the worst case, a long way with an almost equal long spike is
> "simplified"
> to a much shorter way.
>
> In older releases this situation was handled by "preserving" the merge
> point
> in LineMergeFilter, so that the DP filter did not make this error.
> I removed that feature because the "preserved" flag was stored within the
> point object and was used for all higher resolutions and also for all other
> lines or shapes referencing that point. The effect is that the DP filter
> did
> not work as well as possible.
> Of course I did not think about the above problem :-(
>
> I am not yet sure how to fix this problem. I guess I should
> try to detect the spike before executing the DP filter, or
> find a better variant of the preserved points,
> or change LineMergeFilter to avoid merging lines
> when that creates a spike.
> Have to get some more sleep now...
>
> Gerd
>
>
>
>
>
>
> ------------------------------
> Date: Sun, 23 Mar 2014 23:14:10 +0100
> From: michal.rogala at gmail.com
> To: mkgmap-dev at lists.mkgmap.org.uk
> Subject: Re: [mkgmap-dev] dissapearing roads
>
>
>
> If you wan't to reproduce this bug, modify default style in that way:
>
> 1) Remove
>
> highway=tertiary [0x05 road_class=1 road_speed=3 resolution 23]
>
> 2) Replace it with:
>
> highway=tertiary [0x05 resolution 20-20 continue]
> highway=tertiary [0x05 resolution 21-21 continue]
> highway=tertiary [0x05 resolution 22-22 continue]
> highway=tertiary [0x05 road_class=1 road_speed=3 resolution 23]
>
> Proof:
>
> http://imgur.com/j4EdLUd
> http://imgur.com/NaQvmKV
>
>
> :)
>
>
> best regards
>
> Michal Rogala
>
>
> 2014-03-23 22:03 GMT+01:00 Michał Rogala <michal.rogala at gmail.com>:
>
>
> 2014-03-23 21:03 GMT+01:00 GerdP <gpetermann_muenchen at hotmail.com>:
>
> Hi Michal,
>
> You said that GPSMapEdit shows that the way is really missing. I saw lines
> with
> the types you use (0x1101b and 0x1101d), both with and without
> --preserve-element-order.
>
>
> Hi!
>
> Here is part of Domaniewska street missing at Level 3:
>
> http://imgur.com/EhvRxqJ
>
> Selected  (purple) roads are type 0x1101b. Missing part should also be
> 0x1101b
>
> (best seen when you force level by pressing "3" on the keyboard in
> MapEdit).
>
> best regards
>
> Michal Rogala
>
>
>
>
>
>
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