[mkgmap-dev] [Patch v1] reduce line distortion

Tue Jan 26 07:54:11 GMT 2016

Hi Andrzej,

I came more or less to the same conclusion. I think I also have a new
and better idea regarding the data structures and - flow for the housenumber code.
and the brute search algo suggested yesterday seems to be too slow.

The current code suffers from rounding errors which happen because
the position of an address is stored as a double which depends on the 
length of the way segment and the position of the nodes. 
A new node means a lot of recalculations and it is very complicated to compare the positions
of addresses which are assigned to different intervals. 
My new idea whould store the position as an int which gives the metres from
the start of the (original) road. I am not sure if that causes problems with houses
which are before the start or after the end, but I think I should ease many 
calculations. 
2nd idea: Instead of calculating a good split point and searching for a real Garmin 
point close to it which causes small or zero line distortion 
the algo could start calculating all those points Garmin points which are very close or
on the way and check if they can be used to improve address search.
If there are to few good points to split the algo can still combine some addresses at existing
nodes to improve the result. I have to find out how this will work with the random case.

Gerd

________________________________________
Von: mkgmap-dev-bounces at lists.mkgmap.org.uk <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Andrzej Popowski <popej at poczta.onet.pl>
Gesendet: Montag, 25. Januar 2016 23:41
An: mkgmap-dev at lists.mkgmap.org.uk
Betreff: Re: [mkgmap-dev] [Patch v1] reduce line distortion

Hi Gerd,

I guess you already got very complicated code ;)

I'm not perfectionist, I would accept some errors in processing. For
example address placing precision could be in range 20-50m. If there is
a node in this range, I would try use it for multiple addresses.

I'm afraid that inserting a new node within distance 20m from existing
node could distort lines on 24-bit layer and should be avoided.

--
Best regards,
Andrzej
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