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[mkgmap-dev] high-prec-branch ready for trunk?

From Gerd Petermann gpetermann_muenchen at hotmail.com on Tue Mar 4 07:54:31 GMT 2014

Hi all,

I think the branch is ready as it is. Steve and I are still working on a new 
algo to calculate the NOD data (routing information), but this doesn't
depend on high precision and should be done in a different branch.
In short, the branch produces smaller img files with nicer looking
lines and shapes and slightly improved routing and requires around 10% more
cpu time.

If I hear no complains I'll merge on March 6.

The more detailed changes in the branch compared to trunk r3072 are:
1) the program keeps the higher precision of OSM data ( precision ~ 5 cm, 
presuming that OSM data is precise) and tries to detect situations
where the rounding to Garmin map units (precision ~ 2.4 m)
causes distorted lines. The effects are "rounder" roundabouts
and "straigter" straight roads. A nice side effect is
that the algo drops a lot of points which makes img size smaller.
2) polygons with equal attributes are merged and the remaining
points are filtered to also remove distortions. The positive effects
- smaller img size
- nicer looking buildings, see previous post

A negative effect of the current implementation is that two different algos
are used for lines and shapes, e.g. coastlines may differ from the sea shapes.
It is planned to correct that in the near future .

3) Restriction relations are no longer written in a format that prohibits pedestrians 
and emergency (unless the style requests that)
4) the code for the option --link-pois-to-ways was rewritten, see

5) a few optimizations and corrections in the NOD data reduce the size
of the NOD file and seem to correct some routing problems. 
This is not related to high-precision.

6) Precompiled boundary and sea data is ~30% larger as it contains more points,
and also calculaion time for them increased (this is related to higher precision). 
It is probably possible to change that also, for now that means larger downloads.

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