Re: Masking a map correctly with a black background

From: Mary Haley <haley_at_nyahnyahspammersnyahnyah>
Date: Fri, 8 May 2009 14:24:45 -0600 (MDT)

[Dave B, please see below for a question directed at you.]

On Fri, 8 May 2009, Mark Branson wrote:

> Hi Mary.
> Many thanks for coming up with this solution, and sorry for causing you such
> grief with the ice shelves. I may just stick with the original map database
> because I'm not crazy about all of the small islands showing up as little
> white dots now, but I may let our end user make the final call on that.

With the default map database, it is possible to mask these small
islands, but I don't see a way to do this with the Earth..4 database.

Dave, do you know of a way?

> One final question: What font do you have set up on your end? The labels on
> this latest png file you sent me look a million times better than what I
> have. I have *Font : helvetica set in my .hluresfile.

That's what I used. However, I also set:

    res_at_gsnMaximize = True

inside the code so that the plot was maximized in the PS file. This
caused the image to be rotated, and was much bigger.

I then used "convert" from ImageMagick:

     convert -trim -rotate -90 icearea_m.png

The PS file does get rather large when you set gsnMaximize to True.

One thing you can try instead is to increase the density
when/if you use convert:

     convert -trim -denisty 200 icearea1.png

> Thanks again for all your hard work on this. It is very much appreciated!

You're welcome. I hope you are able to get things sorted out.


> Mark
>> Mark,
>> Horrors on my part. I spent a bit of time convincing myself yesterday
>> that the default map database didn't have ice shelves, and now that
>> I've apparently rebooted my brain, I do see them. Grrrr.
>> I'm not sure what I did yesterday, because I know I generated maps
>> that contained solid gray fill where there should have been ice
>> shelves.
>> Well, mystery aside, these ice shelves that you are seeing in black
>> (once you swap the foreground/background colors) is due to the fact
>> that they are considered part of the ocean in the default map
>> database. There's no way to single them out to color them in white.
>> So, we're back to having to use the "Earth..4" database if you want to
>> color those ice shelves individually. You need to have V5.1.0 in order
>> to get these shelves.
>> Please see the attached script (and image), which is taken from your
>> last script, with your original color map added back in.
>> I'm sorry about the go around on this. Now I'll probably spend another
>> hour trying to prove I didn't imagine things yesterday. :-)
>> --Mary
>> On Thu, 7 May 2009, Mark Branson wrote:
>>> Well, I think I understand what's going on in the sample codes and pngs
>>> you sent, but I'm still confused as to how to solve my problem. So I've
>>> trimmed my code down to the bare essentials, and to avoid any possible
>>> confusion that my custom color scheme (with the blues going to white)
>>> might be injecting into the mix I'm just using the "cosam" predefined
>>> color table for now. Then with this code I created three different test
>>> plots:
>>> - The code as it is displayed below (i.e., gray is not being
>>> added to the end of the color table, and I'm not changing the background
>>> and foreground colors). What I see in my postscript viewer is white
>>> continents with the color fill of the ice area data.
>>> - uncomment out the line "i = NhlNewColor(wks,0.8,0.8,0.8)".
>>> Now the continents are gray, but the inland lakes and what I call the
>>> Antarctic ice shelve areas are still white.
>>> - now also uncomment out the setvalues block to change the
>>> foreground and background colors. This plot looks identical to
>>> except that now the inland lakes and ice shelves area black.
>>> I hope it's okay to attach postscript files to this message. I was going
>>> to convert them to png with imagemagick and send those but that actually
>>> makes them look slightly different than the ps files on my machine (Mac
>>> Powerpc desktop).
>>> And below is the actual code.
>>> Thanks!
>>> Mark
>>> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
>>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
>>> begin
>>> b = addfile("/Volumes/xraid3/endworld/ice/",
>>> "r")
>>> data = b->aice
>>> lat2d = b->TLAT
>>> lon2d = b->TLON
>>> data_at_lon2d = lon2d
>>> data_at_lat2d = lat2d
>>> outfile = "icearea1"
>>> wks = gsn_open_wks("ps",outfile) ; open a postscript file
>>> gsn_define_colormap(wks,"cosam")
>>> ;i = NhlNewColor(wks,0.8,0.8,0.8) ; add gray to colormap
>>> res = True
>>> ;setvalues wks
>>> ; "wkBackgroundColor" : (/0.,0.,0./)
>>> ; "wkForegroundColor" : (/1.,1.,1./)
>>> ;end setvalues
>>> res_at_cnFillOn = True ; Fill contours
>>> res_at_cnLinesOn = False
>>> res_at_cnLineLabelsOn = False
>>> res_at_gsnAddCyclic = True
>>> res_at_mpOutlineOn = False
>>> res_at_gsnRightString = "percent"
>>> res_at_gsnLeftString = "July Year 11"
>>> res_at_tiMainString = "Sea Ice Area"
>>> res_at_tmXBTickSpacingF = 60. ; every 60 degrees
>>> plot = gsn_csm_contour_map(wks,data(0,:,:),res)
>>> end
>> <icearea_m.png><icearea_m.ncl>
ncl-talk mailing list
List instructions, subscriber options, unsubscribe:
Received on Fri May 08 2009 - 14:24:45 MDT

This archive was generated by hypermail 2.2.0 : Mon May 11 2009 - 09:43:46 MDT