[mkgmap-dev] Patch v2 for better Autorouting

Tue Dec 1 23:45:57 GMT 2009

I changed some stuff to make routing a bit better. Anyone tried it out?

On 01.12.2009 12:42, Felix Hartmann wrote:
>
>
> On 01.12.2009 12:38, Clinton Gladstone wrote:
>> 2009/12/1 Felix Hartmann<extremecarver at googlemail.com>:
>>> As announced yesterday - here is a patch against the 
>>> default-style-file to
>>> heavily improve Autorouting for cars/motorcycles.
>> So this patch, if I understand it correctly, creates duplicate ways at
>> a higher resolution, but with a lower speed. Do you have any idea why
>> this improves routing?
> Yes because of the fuc**d up Turn time Restrictions AND Garmin 
> GPS/Mapsource trying far too hard to avoid sharp turns at higher 
> speeds (which is a good idea, but not well implemented). The 
> resolution does not matter - I put it at 24 because there is no need 
> for them to be visible, and routing only depends on resolution=24.
>
> This is a dirty hack, but the easiest to do, see below alternative 
> solutions (wrote that in another thread here):
>
> "Actually I have found a method to increase routing distance in 
> Mapsource by 30-100% -due to the functionality introduced yesterday, 
> however it blows up the map size by at least 10%. Will test it a bit 
> more, and then add a patch for mkgmap default style. Based on my 
> findings, I think we would really have to use the dp filter already 
> BEFORE doing anything to get smoother/straighter roads AND work on 
> junctions. I'ld guesstimate the following increases in routing 
> distance (each thing on it`s own):
>
> a) optimal - as discussed
> Junction Angle and creating additional (invisble via typfile) "turn 
> roads" ~ 500%
> - Mapsize increase <5%
>
> b) "Modest" patch:
> Make a last 10m from each junction into any direction duplicate - 
> decrease road_speed patch. >200%
> - Mapsize increase <5%, could even be used together with a) but will 
> probably show no further improvements then.
>
> c)"dirty style-file patch"
> Add slower duplicate roads for 
> primary/trunks/motorways/motorway_links. ~30-100%.
> - Drawback mapsize increase ~10%. The more duplicates, the better, but 
> the mapsize increase will be even bigger.
> If either a) or b) is implemented this dirty hack will not be needed.
>
> However even in comparison with c) - all previous attempts to increase 
> routing quality seem to be pretty basic and unnoticable.2
>> Cheers.
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