[mapserver-dev] WorldMapping issue

[strk]

On Mon, Feb 22, 2010 at 08:33:30AM -0500, Frank Warmerdam wrote:

> I *suspect* the best way to handle it well would be for MapServer
> to understand something special about the dateline, at least about
> geographic coordinate systems, and to split dateline crossing
> requests into two or more requests.
> 
> So the -360 to +360 case should be broken into 3 requests:
> 
> -360 to -180 which would be internally rendered as 0 to 180.
> -180 to +180 which would be rendered as -180 to +180
> +180 to +360 which would be rendered as -180 to 0.
> 
> Then the three results should be mosaiced back together.
> Unfortunately this would require a fair amount of development
> work.

This would pretty much mimic what you can get with OL,
so would present the same limits (handling of labels).

But maybe I'm missing something as I never used the "tile"
support in MS (does it exist ? does it handle labels nicely?)

> I do not thing it would be practical to recognize limits to
> projected coordinate systems and to use such a technique
> though similar wrapping issues can apply in projected
> coordinate systems as well.  For instance this is
> fairly straight forward in mercator, but complicated in
> many projections like the perspective view ones.

I guess the "dateline" concept would be good enough.

--strk;

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