[OpenLayers-Users] Congrats and query? Using spherical Mercator -- can I get at the WGS84 geographic values?

[Richard Greenwood]

On 9/17/07, Mike Adair <madair at dmsolutions.ca> wrote:
> Yes cscs did have that problem.  However the Proj4js version loads only
> the projection class code required based on the projection definition so
> you never need to worry about that.   If you know beforehand what
> projections your app will be dealing with, you can also load the code
> statically.

cscs does not "have that problem" if you are referring to functions
being duplicated. cscs transformation functions are only defined once.
It's a bummer that cscs and Proj4js have split so early in their
respective development. And it's a bummer that we need to "duke it
out" next week. Seems like we'd get a lot further by working together.

> The advantage of the Proj4js approach is that as long as the Proj4
> initialization parameters are available somewhere (statically on disk,
> or in a Web Service like spatialreference.org, or a local interface to
> PostGIS) any projection can be handled.

There's a lot more to a coordinate system transformation than its
Proj4 initialization parameters. You need the forward/inverse
functions, and you need the appropriate datum transformation
functions. And they need to be in JavaScript if you're going to do it
on the client.

-- 
Richard Greenwood
richard.greenwood at gmail.com
www.greenwoodmap.com