[ncl-talk] Fill entire plot area
hachelaf at sca.uqam.ca
Wed Jul 30 23:04:28 MDT 2014
Thanks for this working suggestion, but when trimming the image the pixel
size change, i must keep the same pixel size in each image side because
those images will feed a viewing software like.
Is there another trick to fill the plot area and keep same pixel size.
2014-07-30 10:39 GMT-04:00 Mary Haley <haley at ucar.edu>:
> Hi Rabah,
> One of NCL's quirks is that it always wants to draw things to a square, so
> even when you have a non-square plot, like with a lat/lon projection that
> may be wider than it is high, there is still an invisible square area that
> NCL is plotting to. You will see this especially when you are plotting
> graphics to an X11 window or a PNG image.
> There's not much you can do about the X11 window being square, but you can
> trim the PNG image.
> The way I trim the PNG image is to use a tool called "convert" which is
> part of the free ImageMagick package. "convert" is a handy tool that
> allows you to convert from one format to another (like PS to PNG, GIF to
> JPEG, and PNG to PNG), while at the same time trimming additional white
> space, resizing the image, cropping an image, etc.
> Once you have "convert" you can use it directly in your NCL script via a
> system call, to trim the white space.
> So, for example, with the script you included, I would do something like
> this when calling "gsn_open_wks":
> wks_type = "png"
> wks_type at wkWidth = pixel
> wks_type at wkHeight = pixel
> wks_type at wkBackgroundOpacityF = 0.0
> wks_filename = "wx_map_" + "zoom" + zoom + "_" + "DOM" + \
> sprinti("%0.1i",idom+1) + "_" + \
> lev_str(ilev) + "_" + sprinti("%0.2i", i)
> wks = gsn_open_wks(wks_type,wks_filename)
> Then, after you call "draw" and "frame" on the workstation, you need to
> "delete" the workstation, which merely ensures that the PNG image is
> properly closed. This allows you to then call "convert" to trim the image:
> draw(wks) ;; Now draw map with text strings and frame(wks)
> ; advance the frame
> delete(wks) ; Close the PNG image
> ;---Trim the PNG image
> png_filename = wks_filename + ".png"
> cmd = "convert -trim " + png_filename + " " + png_filename
> You can get the ImageMagick suite of tools from:
> On Tue, Jul 29, 2014 at 7:59 AM, Rabah Hachelaf <hachelaf at sca.uqam.ca>
>> Hi all,
>> I am using the script attached to plot sub-domains from GFS data.
>> When i plot the whole domain or a 1/4 domain area the plot fit correctly
>> with the entire plot area.
>> But when i want plot 1/16 the plotted map does't fit and there is a white
>> bands appear some time on top and bottom and some times on right and
>> left.(like attached images).
>> I tried mpShapeMode = "FreeAspect", this make my maps fit with the
>> entire plot area but this not preserve the map projection aspect ratio
>> Thank you for any suggestions.
>> Best regards,
>> Rabah Hachelaf
>> ncl-talk mailing list
>> List instructions, subscriber options, unsubscribe:
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the ncl-talk