[mkgmap-dev] Nuvi routing performance

Sat Sep 5 19:11:36 BST 2009

Apollinaris Schoell wrote:
> On 5 Sep 2009, at 9:15 , Steve Ratcliffe wrote:
>
>   
>> Hi Mark
>>
>> On 05/09/09 11:44, Mark Burton wrote:
>>     
>>> Playing with my shiny new Nuvi 255, I notice that it can route across
>>> an OSM map of the UK pretty well. It can find long routes
>>> reasonably quickly. In comparison, mapsource 6.13.6 often fails to
>>> determine a route at all and when it does it is rather slow about it.
>>>       
>> Previously someone claimed that on mapsource you needed a routable
>> basemap to get good inter-tile routing, but that on a GPS device you
>> don't. As the basemap is not sent to the device that makes sense.
>>     
>
> Not sure about Mapsource. Roadmap for Mac has the basemap. But still  
> routing doesn't work as good as on the Vista. Wild guess the Vista  
> uses the basemap but Roadmap doesn't.
>   
>> On the other hand the device may already have a routable base map  
>> and so
>> perhaps it uses that if it has one and is the source of the   
>> observation.
>>
>> I know that on my Legend Cx which does not have a UK base map I do not
>> get very good routing across tiles.
>>     
>
> does anyone know how to disable the basemap on a Vista?
> Another wild guess can it be that Garmin adjusts the basemap names/ 
> boundary nodes .... with their map products on tile boundaries to help  
> routing?
>
>   
Really disabling is impossible. What is possible to flash a non routable 
US Basemap which you include in firmware. To go back do the same for the 
european basemap.
I once flashed my hometile of OSM. You can put maps up to around 12Mb as 
Basemap.
Doing such things is however very prone to sending your GPS into Walhalla.

Most of this stuff has been found out by the eastern groups of sellers 
of imported Garmin units and pirated maps.

 There is even a way to flash your serial number (and thereby takeover 
Garmin Accounts from other people) I have not yet seen such a tool in 
the wild, only pics with range of units with identical serial number 
that I take for not faked judging the people who have published them. I 
am sure they use this to sell you "orignial European units" as the 
serial number should usually be enough to send the gps to German support 
(instead of having to send it to Garmin UK). Too bad that those groups 
not start hacking the firmware to offer some needed functions (e.g. 
reading tracks from SD, or optimising the routing algorithm for offroad 
navigation) but only focus on cracking for commercial success.
>> ..Steve
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>>     
>
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