[OSRS-PROJ] orthographic projection with proj4 and mapserver.

Norman Vine nhv at cape.com
Thu Aug 14 11:24:32 EDT 2003

Judd Taylor writes:
> > "Gerald I. Evenden" <gerald.evenden at verizon.net> wrote:
> >
> >
> > Proper graphical clipping is a tough problem.  I
> I could use some pointers in this arena as well, if anyone on this list has
> any. Right now I'm using the General Polygon Clipping (GPC) library to clip
> my polygons from the GSHHS coastline set (GPC website:
> http://www.cs.man.ac.uk/aig/staff/alan/software/gpc.html). Unfortunately,
> this takes forever to clip the larger polygons in that coastline set (~1.4
> million points).
> Anyone know how I can speed this up? Maybe a different library? Maybe a
> different format for the polygons? I can't seem to find any good references
> for this sort of thing anywhere online. Any advice would be appreciated!

Itertively reduce the resolution of the data so that you have several data sets
each appropriate for a range of scales

You could also clip these into areas and then you would only need be
concerned with polygons in those areas that are in view


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