IDL 5.2.1 -- bug in filled contours?

[Bob Yantosca <bmy(at)triton.harvard.edu>]

Hi all,

I've noticed a potential bug in IDL 5.2.1 when you try to overplot filled
contours atop a map.  Basically, what happens is that you get a
small square of color that covers a tiny square centered on Lat=0,
Lon=0, instead of covering the entire map area.

See below for a test program I've devised to illustrate the error. The
first plot (with regular color contours) comes out fine.  When you use the
/FILL keyword then you run into this bug.  (I tried /CELL_FILL too, but
that didn't make any difference). 

Per Martin Schultz's suggestion, I tried resetting the Y-axis indices so
that the poles were -89.9 and +89.9 (instead of -90 and +90), but on my
system (SGI-IRIX), that didn't help at all.

Any suggestions?

Thanks much,

Bob Yantosca
bmy@io.harvard.edu

----------------------------------------------------------------------
pro Test_Contour
   loadct, 27                          ; EOS-B Colortable
   !P.MULTI = [0, 1, 2, 0, 0]          ; 2 plots per page
   TmpData  = Dist(72, 46)             ; Test array for plot
   XArr     = findgen(72)*5.0 - 180.0  ; X-indices
   YArr     = findgen(46)*4.0 - 90.0   ; Y-indices
   C_Levels = findgen(10)*4            ; Contour levels
   C_Colors = findgen(10)*10           ; Contour colors

   ; Call MAP_SET and CONTOUR with unfilled color contours
   Map_Set, /Grid, /Continents, Color=2, $
      Title='IDL 5.2 Color Contours (OK)'

   Contour, TmpData, XArr, YArr,  $
      Levels=C_Levels, C_Colors=C_Colors, /OverPlot

   ; Call MAP_SET and CONTOUR with filled contours
   Map_Set, /Grid, /Continents, Color=2,  /Advance, $
      Title='IDL 5.2 Filled Contours (/FILL)...screwed up'

   Contour, TmpData, XArr, YArr,  $
      Levels=C_Levels, C_Colors=C_Colors, /OverPlot, /Fill 
end

----
Bob Yantosca          | Phone: (617) 495-4517   \  "Ooooh...floor pie!"
Scientific Programmer | FAX:   (617) 495-4551    \    -- Homer J. Simpson
Atmospheric Chemistry | Email: bmy@io.harvard.edu +------------------------- 
Harvard University    | WWW:   http://www-as.harvard.edu/people/staff/bmy/