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[mkgmap-dev] Error processing tile

From Gerd Petermann gpetermann_muenchen at hotmail.com on Mon Jun 5 07:48:39 BST 2023

Hi Ticker,

okay, after some more debugging I think I understand. The problem is/was that the code in PredictFilterPoints assumes that the obsolete point removal happens before line splitting,
but the actual order in MapBuilder is/was different (and wrong).


Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Gerd Petermann <gpetermann_muenchen at hotmail.com>
Gesendet: Montag, 5. Juni 2023 08:14
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] Error processing tile

Hi Ticker,

The fix helps with the data from Carlos and it also seems to improve the img size.
So far so good.
I don't understand if this patch really fixes the error or if just changes "something" which prevents the error.
Or in other words: How does it prevent the overflow of the counter?


Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap at jagit.co.uk>
Gesendet: Sonntag, 4. Juni 2023 10:15
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] Error processing tile

Hi Gerd

Realising that something is increasing the number of lines in a
subdivision and I wasn't getting the problem with my build I remembered
I'd noticed that this could happen due to changes made to the line
filtering in the low-res-opt branch work and supplied
filterOrderLowRes.patch to restore some of the vital orderings - see
forwarded email.

The vital part is relating to MapSplitter/Area predicting the maximum
number of splits to a line after RoundCoords & RemoveObsoletePoints
have done their work.

Attached is patch of the code I've been using appropriate to trunk.


-------- Forwarded Message --------
From: Ticker Berkin <rwb-mkgmap at jagit.co.uk>
To: Development list for mkgmap <mkgmap-dev at lists.mkgmap.org.uk>
Subject: Re: [mkgmap-dev] Problems with sea in overview map
Date: Fri, 21 May 2021 17:10:07 +0100

Hi Gerd

I'd been doing some investigation of filters ordering (based on trunk).
I'd also done the pre-filtering of lines & shapes by minRes.

My conclusions are:

It is better to run SizeFilter after RemoveObsoleteFilter.
It is more efficient to run DP filter after both of these.

LineSplitterFilter should be run after everything that can remove
It is more efficient to run DP after RemoveObsoleteFilter.

I've adapted my changes into a patch for the low-res-opt branch, along
with removal of some resolution tests that are now redundant.

For the contourFilters, I've left DP as the first filter but moved
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