[mkgmap-dev] Country specific rules and default country / region or "--country-name=..."

Thu May 5 22:03:36 BST 2011


On 05.05.2011 23:01, WanMil wrote:
>>> The locator branch is in an early alpha status. Such small
>>> optimizations can be added later on when the main problems are solved.
>>>
>> Do you consider this as small optimization?
>
> Yes. If you have other numbers please post them.
>
> As long as splitter/mkgmap handles rect tiles only and not polygon 
> shaped tiles it won't help (for most cases) to define a region which 
> is assigned to all objects. So you save the country assignment only.
>
> And the processing time for this is neglegable compared to the other 
> assignements of region and city.
> The reasons for this are very easy.
> 1. Counts
> A common tile contains data of a bit more than one country on average.
> But it contains up to some 1000 boundaries of other admin levels.
> So you have a lot of more queries to do for non country information.
>
> 2. Size of countries
> Most rectangular tiles cover one country only. Using the precompiled 
> boundaries of the locator branch you get exactly one rectangular 
> polygon for the single country and that's very low cost for retrieving 
> all containing elements: it's just all.
>
>>
>> I think most people use / create maps from country extracts by geofabrik
>> anyhow, so this is the first important step and save a lot of processing
>> time / maybe even be enough for many people to find street addresses.
>
> Solve the main problems first (what to do with streets crossing from 
> one city to another - cut them?, find a fast rtree like structure to 
> perform the queries etc.)
> Then you can start to measure the performance and to think about 
> optimizations. At least you can think about fine optimizations. And 
> then you need someone who implements them: kind inviation for you to 
> do so.
>
> WanMil
okay, thanks for the clarification, I thought the country selection 
takes more.