[OSM-dev] A new way to split the planet

Nic Roets nroets at gmail.com
Sun Aug 16 09:52:34 BST 2009


On Sun, Aug 16, 2009 at 4:15 AM, Paul Johnson <baloo at ursamundi.org> wrote:

> On Fri, 2009-08-14 at 20:07 +0200, Nic Roets wrote:
>
> > 3. Use an OO spreadsheet to choose the rectangles (density4.ods). OO
> > will makes it quite easy: As you drag to highlight a rectangle, it
> > will display the sum (of nodes) in the status bar. This way you can
> > see how much data will be in the rectangle. I stayed below 14,000,000
> > which works out at .osm.gz of less than 300MB and gosmore files of
> > less than 400MB. It also works well if you compose expressions like
> > MAX(SUM(A1:K12);SUM(D9:M21)), because you can hit F2 to see how the
> > rectangles overlap and even change them. I ended up with 58
> > rectangles, which will increase as the planet gets larger.
>
> For the sake of simplicity for someone who isn't a spreadsheet nerd,
> would it be possible to get the relevant cell ranges named?
>

If you look at the spreadsheet from row 1027, you will see that I gave them
names. In some cases the same name applies to multiple ranges like US East &
Midwest. It's difficult to give them all understandable individual names
because if they span multiple cities and / or multiple states, but does not
cover any city or state completely and you give them a name, it may just
mislead people. But the html image map helps to show people what is
available. Displaying the rectangles on Open Layers should be quite easy.

In the US East Coast the density is high and everything is connected to
everything else (no natural or political borders). So a pattern of
overlapping rectangles works well. But the spreadsheet also allows you to
exploit the natural and especially the political boundaries: If you are in
some African country you'll rarely ask your GPS for the shortest route to
some European country.

On Sat, 15 Aug 2009, Nic Roets wrote:
>  I ended up with 58 rectangles, which will increase as the planet gets
> larger.
Now I'm worried.

Fortunately the new rectangles will be in Europe. So I can use the pattern I
used in denser US.
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