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

Thu May 5 22:01:33 BST 2011

>> 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