[OpenLayers-Dev] Know of any offline datasets compatible with
crschmidt at metacarta.com
Fri Nov 23 08:44:41 EST 2007
On Fri, Nov 23, 2007 at 09:07:47AM +0000, Ian Mayo wrote:
> > Totally offline data can be easy... if it is small or your storage is
> > big. Storing the top 7 levels of the vmap0 dataset as tiles
> > is something like 200MB of data. Depending what you actually want to do,
> > this might be useful or not -- but I'm almost positive that it's going
> > to be more useful than trying to actually draw the world as a vector.
> I presume you're describing the use of a standalone mapping server to
> support the OpenLayer instance.
Nope. I've done it in the past (http://labs.metacarta.com/on-a-stick/)
by pre-generating a cache using TileCache, then using the
Layer.TileCache class to access it.
> I'm hoping to avoid this - with the
> user just having to double-click on "index.html" & view the mapping
Right, I understand that. Though I'll point out that it is possible to
bundle all dependancies for a full OpenLayers stack into a single,
small, Python based Webserver, and use that to server data... Then
you've got Linux and OS X support, and if you build your distribution
right, Windows support too.
> Overall, it seems the only way to get external data in is via cached
> WMS images. So, the best I can think of is to "somehow" get a world
> vector shoreline dataset written as transparent-gif images in world
> wind data format, then display these images as a "higher" layer than
> any other image layers: thus overlaying a coastline.
Er, yes. I'm not sure why you make it sound so speculative, though :)
Does the task sound unusual or difficult to you in some way?
You can use the world freemap dataset:
Combined with a lightweight mapfile, you can get a nice set of world
borders from this: http://world.freemap.in/
Then use TileCache, tilecache_seed it down to zoom 6 or what have you,
and dump the tiles over to a disk.
This isn't new territory for me, so if you're confused on the matter,
please feel free to respond and ask more questions.
More information about the Dev