Bug #503

Clipping at map borders goes back and forth

Added by Joaquim over 4 years ago. Updated over 3 years ago.

Status:In ProgressStart date:2014-02-06
Priority:NormalDue date:
Assignee:-% Done:

0%

Category:-
Target version:-
Affected version:5.x-svn Platform:

Description

In the sequence of #497 a new problem surfaced. The clipping at +/-180 displays the classical horizontal lines that occur when the clipping fails.
The testing file is still big (~40 Mb uncompressed) and maybe we can reduce it while still displaying the problem, but I have not tried to do so.

File is available at w3.ualg.pt/~jluis/ftp/tmp/lixo1.dat.bz2

and a command to reproduce the problem is:

psxy -R-20/195/10/84 -JR90/20 -A -Ggreen@50 -W0.1p,black,solid lixo1.dat -Vd -Ba -P> eurasia.ps

badclip.pdf (9.94 KB) Paul, 2014-02-06 11:12

Associated revisions

Revision 12868
Added by Paul over 4 years ago

Add test script for issue #503

History

#1 Updated by Paul over 4 years ago

  • File badclip.pdf added
  • Status changed from New to In Progress

I have added a new test script (psxy/clipping6.sh) which indicates the problem on a tiny polygon. The output is shown attached here as well. Note that the clipping is correct for the Mercator map but fails badly for the same region for Robinson or Winkel Tripel, possibly others.

#2 Updated by Paul over 3 years ago

Just make a few more points on this:
  1. pscoast does not have this problem since it plots chunks that have boundaries that are meridians and parallels
  2. The general wesn clipper will have to fill in the path between the exit and entry point with a meridional path.

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