[mkgmap-dev] New clip box functionality for splitter

Sun Sep 16 11:17:20 BST 2012

Hi Geoff,

clipping is already implemented by osmosis or osmconvert. But this 
requires another step to generate the map. So I think it is a good idea 
to add this option to splitter.

I expect that clipping will not be as easy as it sounds like. If you 
have a way that intersects the clipping area you need the points inside 
the clipping area (easy) but also the first point outside the clippling 
area (not so easy). If you want to be correct you have to read and store 
all nodes because you cannot be sure that a node outside the clipping is 
not the first "outer" node of a way.

Regarding the dev tools: there is no specific tool required. I use 
Eclipse but you are free to choose.

WanMil

> I am interested in contributing to the development effort of mkgmap and
> have come up with what should be a simple project to begin with. I am
> thinking of adding a clip box to the splitter so that any nodes outside
> the box will be ignored, and any lines, polygons will be clipped to the
> clip box (I have chosen clip so as not to confuse it with the bounds
> option).
> This has come about as I have been generating a map for Sri Lanka as I
> am going on holiday there in October. Cloudmade has a separate extract
> for Sri Lanka, but is very out of date. To get up-to-date data I have to
> download all of Asia from Geofabrik and process the whole lot, loading
> into Mapsource, then selecting the few tiles that cover Sri Lanka and
> transferring them to device.
> By supplying a clip box I could give a lat,long combination for the
> bottom left and top right corner; and clip to that – in the case of Sri
> Lanka the splitter would probably give me a single tile to process
> through mkgmap. It would also mean I do not need Mapsource to produce a
> gmapsupp.img file at all.
> If anyone knows why I should not try this project please let me know.
> A question: Is there a preferred development environment system for
> mkgmap or splitter on Windows, such a Eclipse or NetBeans???
> Regards, Geoff.
>