[OSRS-PROJ] Orthographic Projections and MapServer

Norman Vine nhv at cape.com
Thu Aug 21 12:54:25 PDT 2003


Bart Adriaanse writes:
> 
> > The only sure method I know of is to clip the polygon to the great circle that
> > is the 'rim' of the projection prior to submitting it to the draw routine and
> > perhaps also the proj forward projection.
> 
> I suppose we agree on this, but would you agree it would be a nice feature
> of the projection engine to have this sensible solution built in by default
> ?

I agree and AFAICT Proj does have a sensible solution

my_project_point(...)
{
  ...
  PJ_FWD(...)
  if( !pj_errno)
  { 
     OK - Do my thing
   } else {
     Handle_Error_Condition
  }
  ...
}

IMHO What we need to have is a 'rendering engine' that does the 
'sensible thing' for HANDLE_ERROR_CONDITION

So 'all' we need todo is hash out just what the 'sensible thing' is for
those cases that we know 'apriori' will fail.  :-)

Cheers

Norman


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