[mkgmap-dev] Missing ways part 1

Sat Oct 23 00:33:17 BST 2010

The only thing that seems to work for me on Australia if I use the default
style is overlap of 50000. If I use any thing less I get lines of maritime
boundaries drawing all over the place and have some missing ways.

I even tried to add extra nodes on the maritime booundaries so I could
decrease the overlap, but this didn't work. It's almost like if the tile
size is larger than the overlap it will cause problems even though on the
input file nodes are on the tile.

Markus.

  _____  

From: mkgmap-dev-bounces at lists.mkgmap.org.uk
[mailto:mkgmap-dev-bounces at lists.mkgmap.org.uk] On Behalf Of Scott Crosby
Sent: Saturday, 23 October 2010 5:39 AM
To: ar2988-os at yahoo.co.uk; Development list for mkgmap
Subject: Re: [mkgmap-dev] Missing ways part 1

On Mon, Oct 18, 2010 at 3:38 PM, Adrian <ar2988-os at yahoo.co.uk> wrote:

Marko wrote:
> If I remember previous discussions correctly, splitter does not split
> lines exactly at the tile border, but instead it includes all nodes
> that are not too much outside the tile.

That is also what I understood. Splitter includes in each tile, the
nodes that fall within the tile, and also the nodes in an overlap region
around the tile. The width of the overlap can be set with --overlap.

> An almost-straight long way can be drawn with few nodes. You could
> help the situation by adding a point to the line close to the
> splitting border.

I would expect it to cause a problem, if a particular way does not have
a node in the overlap region. The difficulty with your fix is that it
would only work for me (and only if I use the same areas.list each
time); it will not work for other users. Also, it will not work for me
in the long term, because data is continuously added to OSM, so the
tiles need to be made smaller as time goes on.

If the overlap region is always bigger than the largest internode spacing
between two nodes in a way, then this shouldn't be a problem. Decide a
distance, say, 20km, and then set the overlap to be that distance. Finding
and fixing ways that violate the rule can be done by a bot.

As a workaround, until the mkgmap problem is diagnosed, increase the
overlap. Check out the crosby_integration splitter branch. It can correctly
handle large overlaps.

Scott

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