[ncl-talk] Artifacts at date-line

[Wei Huang]

Rick,

It could be all three cases, e.g., it could be in the pre-tiled image (but we could not verify, as it is a square),
Or in the individual tiles (again, without put them together, we do not know), or it could be Google Map’s.

Yes, it happened at date-line, which is along the tile boundaries (pre-tiled, and individual, as the plot region
Is -180 to 180). Indeed it puzzles me, as the line only appears in partial of the date-line, not all though,
Otherwise, we could know that we have missed few columns or so.

It also could be from Cairo, as usually, NCL generates plot as square/rectangular, also with perimeter/tick marks.
If Cairo missed one or two pixels at the edge, it is hard to notice, but show up when we try to stich it as cylinder.

I have run out of ideas, that is why I ask you and other people in the mailing list for help.

Thanks for looking into this!


Wei Huang

From: Rick Brownrigg [mailto:brownrig at ucar.edu]
Sent: Tuesday, January 12, 2016 2:57 PM
To: Wei Huang
Cc: ncl-talk at ucar.edu
Subject: Re: [ncl-talk] Artifacts at date-line

Hi Wei,
I'm not sure where the lines are coming from.  Are they present in your pre-tiled image?  Are they in the individual tiles.  Or is it a Google Map artifact?
I presume they are occurring along tile boundaries?  Its curious that in the image you sent, the double-lines don't cut across all contour levels?!
Rick


On Tue, Jan 12, 2016 at 12:12 PM, Wei Huang <whuang at univ-wea.com<mailto:whuang at univ-wea.com>> wrote:
I am plotting a transparent image (of precipitation) with png file, then slice it to (for example 16, or 64) tiles and then
Put these tiled images on top of Google Map. As you can see, there are two vertical lines (sometimes none, and sometimes one).

Is there any way we can get rid of those lines?

Here are the major resource parameters:

   res                   = True
   res at mpProjection      = "Mercator"       ; choose projection
   res at mpGridAndLimbOn   = False            ; turn on lat/lon lines
   res at mpPerimOn         = False            ; turn off box around plot
   res at mpOutlineOn       = False
   res at mpFillOn               = False
   res at mpLimitMode       = "LatLon"
   res at mpMinLatF         =  -85.0511
   res at mpMaxLatF         =   85.0511
   res at mpMinLonF         = -180.0
   res at mpMaxLonF         =  180.0

   res at vpXF              = 0.0
   res at vpYF              = 1.0
   res at vpWidthF          = 1.0
   res at vpHeightF         = 1.0

   res at gsnAddCyclic      = True

   res at cnFillOn             = True              ; color plot desired
   res at cnLineLabelsOn       = False             ; turn off contour lines
   res at cnLinesOn            = False
   res at cnFillMode           = "AreaFill"
   res at cnLevelSelectionMode = "ExplicitLevels"   ; set explicit contour levels
   res at cnLevels            := levels
   res at cnFillColors        := colors
   res at cnConstFEnableFill   = True ; so zoomed in that filed is const
   res at cnConstFLabelOn      = False

   res at lbLabelBarOn         = False

Thanks,

Wei Huang
whuang at univ-wea.com<mailto:whuang at univ-wea.com>



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