[mkgmap-dev] Bug in LocationHook?

Sat Jan 7 20:58:52 GMT 2012

Hi WanMil,

I think the problem is that we sort the boundaries before analysing the
lies_in tag. If we first fill the missing zip code tag (and maybe the
admin_level tag as well) from the boundaries found in lies_in, we should not
see the problem that elements are removed too early.
I'm just trying that.

Ciao,
Gerd

WanMil wrote
> 
>> Hi,
>>
>>
>> WanMil wrote
>>>
>>> that sounds strange. I think recreating the quadtree would only be
>>> benficial if recreating takes less time than removing elements. I wonder
>>> if that's the case?
>>>
>>
>> I think the current quadtree implementation has one problem: As long as
>> it
>> still contains a few elements, a get(...) takes more or less the same
>> time.
>> I guess that's because it still calls a lot of intersect() calculations
>> to
>> return a result.
>> I am still searching for an error which seems to slow down the program
>> too
>> much, but my patch does this:
>> - It keeps the list elemList
>> - If currLevel is changed, it checks if the previous level caused any
>> changes to the elements in the quadTree. If not, the whole elemList is
>> tested, all elements that are fully worked out are removed.
>> If the remaining list is much smaller, the quadtree is replaced.
> 
> Sounds reasonable. There might be another solution within the quadtree:
> At the moments subtrees are not reduced. At an early stage of 
> implementation I did have implemented this but it did not have an 
> advantage.
> Now the quadtree uses other datastructures which might be easier to 
> reduce. So a node which is not a leaf can be reduced after a successful 
> remove operation if all childs are leafs and the sum of points in the 
> leafs are lower than the maxsize. That should be not too complicted to 
> implement and does not require any special handling in the LocationHook.
> 
> I will give it a try within the next days.
> 
> WanMil
> 
> 
>>
>> Ciao,
>> Gerd
>>
>>
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