[mkgmap-dev] [Patch v5] LocationHook with new Quadtree

Thu Jan 19 20:51:20 GMT 2012

> Hi WanMil,
>
> I have coded a first version of the preparer with quadtree. It works so
> far, the bnd files are not
> much bigger and the format is still the old one (boundaryLister can read
> them), the creation is a
> little bit faster compared to trunk.

Great!

>
> I think I understand now your question regarding the merging the tags.
> In the trunk implementation we save all kinds of tags for the boundary,
> although only a few are
> needed by LocationHook. Now, when BoundaryQuadTree.Node.merge() has
> executed, I have
> some areas that are intersections of two or more boundaries. It is clear
> that we have to save the
> location relevant tags, but what about the other? Can we simply ignore
> them? I guess no, because
> we loose information like name:en, name:fr if they exist.

Yes, that's a problem. The name that is used for the boundaries is taken 
from the name-tag-list option. I think this should not be dropped - 
otherwise we loose the option to create a map with french or spanish 
country and boundary names. But the tags used in the name-tag-list 
option are not limited to "name:*" tags. So we cannot create a rule 
which tags could be dropped during preparation.

It would be possible to create a dictionary with tag names at the 
beginning of each bnd file. But I think it's better to implement the 
whole functionality first with the current bnd file format. Once that is 
done we might check if it improves the performance to optimize the bnd 
format. But I doubt that it makes a big difference because most of the 
bnd files are not very big. 99% of the bnd files of the world are 
smaller than 1 MB.

WanMil

>
> Any ideas?
>
> Ciao,
> Gerd
>
>