[mapserver-dev] WorldMapping issue

[strk]

Hi all,
I've been reading the WorldMappingIssues [1] wiki page and did not
find a use case which I belive would be useful (or at least worth
discussing).

[1] http://trac.osgeo.org/mapserver/wiki/WorldMappingIssues

The use case is getting a kind of "tiled" output, that is replicating
the image containing full-extent in zones which are outside of it.
An example might help understanding. 
Say this is the input data

  8--. . . . . . . . .
     .               .
  6--.   +-------+   .
     .   |       |   .
  2--.   +-------+   .
     .               .
  0--. . . . . . . . .
     |   |       |   |
     0   2       6   8

And that the dotted-line above is the max valid extent
for the input data projection.

Now you want to render that data _multiple_times_
over a zone which is bigger than the valid extent:

   . . . . . . . . . . . . . . . . . . . . . . . . .
   .               .               .               .
   .   +-------+   .   +-------+   .   +-------+   .
   .   |       |   .   |       |   .   |       |   .
   .   +-------+   .   +-------+   .   +-------+   .
   .               .               .               .
   . . . . . . . . . . . . . . . . . . . . . . . . .
   |   |       |   |   |   |   |   |   |       |   |
  -8  -6      -2   0   2   4   6   8  10      14   16
  (0) (2)     (8) (*)             (*) (2)     (6)  (8)

Points 0 and 8 are the same (think dateline).
Ordinate values between parens are computed
"wrapping" around valid range.

Note that in this case it's not a single shape which
goes "beyond" valid extent (which is discussed on the
wiki). 

Also note that letting this handled by the client (say OL
with wrapDateLine) has the limit of not dealing labels and
the need of knowing more about the WMS projection.

Maybe support for this is already implemented and I'm unaware
(very likely) so I'd appreciate any informations about that.

--strk; 

  ()   Free GIS & Flash consultant/developer
  /\   http://foo.keybit.net/~strk/services.html