[gradsusr] Troubles Overlaying Data Onto A Premade Basemap

[Jennifer Adams]

Hi, Aaron -- 
The -t option with Cairo is not quite the same as it was with the old GD library and printim. This is because graphical elements are layered on top of one another with Cairo (think of having a stack of colored pixels when you draw many things in the same spot), whereas with with GD a new graphical element would simply change the color value of the pixel (the stack is always one pixel high.) When it comes time to gxprint, and you use -t and -b, the background will only show through if the stack is one pixel high, otherwise the -t color just reveals the pixel beneath it in the stack, not your background image. The -t option really only works with the background color and nothing drawn on top of it. 

So, check if you have a 'set display black' and 'clear' at the top of your script, and then wherever the background is visible, your basemap image should show through when you use -t 0 and -b. Alternatively, if you've got 'set display white' and 'clear', then use -t 1. 

If you still can't get what you want, try using a defined color that is fully transparent instead of the -t option. 
--Jennifer



On Apr 19, 2014, at 2:03 PM, Perry, Aaron @ LSC wrote:

> Good Afternoon All,
> 
> I'm currently having an issue where I'm unable to use gxprint to overlay model data on top of a pre-made basemap background (which I've attached to this email).
> 
> Here is the gxprint code that I'm to use to try to accomplish this:
> 
> 
> 'gxprint 'path1''path''currdate'/'curr_run'Z/'model'_'region'_'var'_'fhr'.png png  -b 'path1''path'/ahps_gulf_basemap.png -t 0 x1500 y1125'
> 
> 
> Onward and Upward,
> 
> Aaron D. Perry
> Atmospheric Sciences
> Lyndon State College
> Class of 2016
> Boston, MA 
> Twitter: @AaronPerryLSC
> Mobile: 617-780-4312
> <ahps_gulf_basemap.png>_______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr

--
Jennifer M. Adams
Center for Ocean-Land-Atmosphere Studies (COLA)
111 Research Hall, Mail Stop 2B3
George Mason University
4400 University Drive
Fairfax, VA 22030 





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