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[mkgmap-dev] additional arcs patch

From GerdP gpetermann_muenchen at hotmail.com on Thu Feb 20 21:41:20 GMT 2014

Hi WanMil,

one difference to trunk is the formula that is used to convert meters to
length
in MapUnits. I've changed it to the value that Steve found with the display
tool.
The effect is that MapSource + BC show a different travel time for exactly
the same 
route while it shows the same road length.
I expect only changes when using "faster time", and probably only car
routing is effected. 

Gerd 


WanMil wrote
> Ignore the Google result.
> 
> I am quite sure that there is a difference between the high-prec-coords 
> branch and the trunk. I need to recompile the map with the trunk to 
> confirm this.
> 
> WanMil
> 
>> Please, forgive my 2 cents on this:
>>
>> Depending on which projection each system is using, distance calculation
>> may (and usually) differ by that much and maybe more.  As far as I know,
>> Google uses a Mercator-like projection on a spherical Earth model, which
>> is not correct since Google coordinates refer to the WGS-84 ellipsoid.
>> So you can expect differences, greater with higher latitudes.
>>
>> So don't use Google as an accurate reference.
>>
>> all the best,
>>
>> Paulo
>>
>>
>> 2014-02-20 17:23 GMT-03:00 WanMil <

> wmgcnfg@

>  <mailto:

> wmgcnfg@

> >>:
>>
>>     Hi Gerd,
>>
>>     which difference do you expect regarding the indirect links? I want
>>     to get an idea what I should check on my device.
>>
>>     I have compiled a map using the patch and it seems that distances
>>     are slightly underestimated.
>>     One example: The distance between Hambug, An der Alster and Munich,
>>     Maximiliansplatz:
>>     MapSource: 776km
>>     Google Maps: 788km
>>     Both use the same route.
>>
>>     I didn't notice it before.
>>
>>     WanMil
>>
>>         Hi all,
>>
>>         attached is a patch for r3065 in the high-prec-coord branch.
>>
>>         It should improve long distance routing, as it adds additional
>>         arcs from minor roads to major roads (so called indirect links).
>>         Maybe the improvement is only seen on the device.
>>
>>         It would be great to hear some test results (good or bad),
>>         compared to trunk r3057 and compared to r3065.
>>
>>         A compiled binary is here:
>>         |http://files.mkgmap.org.uk/__download/179/mkgmap.jar
>>         <http://files.mkgmap.org.uk/download/179/mkgmap.jar>
>>
>>         |Gerd
>>
>>
>>
>>
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