Re: Question about CellFill

Ian,

For what it's worth, I looked at the output tst.ps from your sample
program below. At both 1X and 10X zoom, I saw no trace of the
problem you describe. On a test printout on one of our color
printers, I also got no trace of cell lines or Moire effect.

I am running NCL V4.2.0.a034 on Mac OS (Darwin 8.8.0). My
postscript viewer is gv (Ghostview) 3.6.1.

--Dave A.
CU/CIRES Climate Diagnostics Center (CDC)
NOAA/ESRL/PSD, Climate Analysis Branch (CAB)

Ian Ross wrote:
> Hi there,
>
> I've been using NCL for a while now (great tool - thanks a lot to the
> developers, and thanks to UCAR for making it freely available) and I
> have a question about some maps I've been making.
>
> These are contour plots filled using CellFill, and the problem is
> essentially that there are fine white lines between the filled cells
> on many plots. You can see what I mean on the first plot of the last
> example on:
>
> http://www.ncl.ucar.edu/Applications/orca.shtml
>
> and also in the output from the test script at the bottom of this
> message.
>
> The lines between the filled cells are very fine, but they are real.
> There are two questions, I suppose:
>
> - Is it possible to make them go away? Is this some sort of rounding
> problem in the calculation of the cell boundaries, or is it
> something harder to fix?
>
> - Are the lines going to show up when these plots are typeset?
> They're clearly visible in a PostScript viewer, but not really
> visible in printed output (medium-quality monochrome laser
> printer). They also produce a moire effect in some cases (you can
> see this in the ORCA example above, in the Bight of Benin) and that
> might cause trouble with higher resolution printing.
>
> Thanks a lot,
>
> Ian Ross.
>
> ----------------------------------------------------------------------
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
>
> begin
> pi = 4.0 * atan(1.0)
> lat = fspan(0.0, 90.0, 46)
> lon = fspan(0.0, 360.0, 181)
> tstdat = new((/ 46, 180 /), float)
> do latidx = 0, 45
> tstdat(latidx, :) = sin(3.0 * lon(0:179) / 180.0 * pi) * \
> exp(-((lat(latidx) - 30.0)^2) / (2.0 * 15.0^2))
> end do
>
> wks = gsn_open_wks("ps", "tst")
> gsn_define_colormap(wks, "rainbow")
>
> res = True
> res_at_sfXArray = lon
> res_at_sfYArray = lat
> res_at_cnFillOn = True
> res_at_cnFillMode = "CellFill"
> res_at_cnLinesOn = False
> res_at_cnLineLabelsOn = False
> res_at_gsnPolar = "NH"
> res_at_gsnSpreadColors = True
>
> map = gsn_csm_contour_map_polar(wks, tstdat, res)
> end
> ----------------------------------------------------------------------
>

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Received on Mon Feb 05 2007 - 16:22:32 MST