[OpenLayers-Users] Tile Layers with arbitrary projections?
richard at winwaed.com
Wed Jul 8 14:56:06 EDT 2009
I am looking to build an online map page/app/site that will display the
map in a number of different projections.
Not just changing the geoid/datum, but changing the actual projection
(aside: virtually every online map use Mercator - I see the sample on
the Openlayers home page uses a different cylindrical projection, as
does MapQuest, I wish to be more adventurous with conics,
pseudo-cylindricals, etc - the exact projection(s) have yet to be decided)
I know you can adjust the projection with MapServer & OpenLayers (with
proj4js), so I will probably take this approach and use TileCache to
help reduce server loads.
The basemap will remain unchanged, so instead of using WMS (or a similar
on-demand service), is it possible to create a set of tile files ahead
of time, and "serve" these simply by exposing the tile directory
hierarchy on a webserver?
From what I have found on the OpenLayers site, it looks like this is
possible, but can this be done with an arbitrary projection?
How can the tiles be produced?
The advantage of doing this is that it is quicker (Apache/etc simply has
to serve a file rather than run an application), and the tiles can also
be distributed using Amazon S3 / CloudFront (faster still, and easier to
keep costs&performance under control).
I have been able to do this quite effectively using MapCruncher and
Bing/Virtual Earth. It would great if I could also do it for arbitrary
projections and with OpenLayers.
The primary purpose of these maps is as a demo for a series of articles
I'm going to write for GeoWebGuru.com. It started as an opinion piece,
and now I feel I should "put my money where my mouth is" and actually
implement something! It may simply serve as a low bandwidth demo and
example for how-to articles. However I intend it to have some utility,
so I want to be able to handle higher traffic loads without being cut
off or charged by my webhost!
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