[OpenLayers-Dev] Know of any offline datasets compatible with
ian at planetmayo.com
Fri Nov 23 04:07:47 EST 2007
On 22/11/2007, Christopher Schmidt <crschmidt at metacarta.com> wrote:
> On Thu, Nov 22, 2007 at 08:36:40PM +0000, Ian Mayo wrote:
> > So, can anybody point me to datasets representing world coastlines or
> > country outlines that are recorded in one of OpenLayers vector file
> > dataset?
> There is no way that OpenLayers can render even a very low resolution
> data set of country outlines for the whole world. Figure, as a guess,
> about 100 features, max, and that's if they're relatively simple.
> Complex vectors -- even simplified complex vectors -- are going to cause
> browsers to hang, rather than render the data.
Had forgotten about this constraint.
> 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. I'm hoping to avoid this - with the
user just having to double-click on "index.html" & view the mapping
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.
More information about the Dev