[GEMPAK #WUQ-124584]: GPMAP question about overlays

Hi Kevin,

If I understand you correctly, you are overlaying surface data on top of radar 
image files by calling multiple instances of GPMAP in a script.  Unfortunately 
there's no easy way to accomplish what you want: to generate surface data 
overlays once once per hour while generating radar image layers more often.  

A more labor-intensive option may be:

Create surface map files (gif) once per hour in the cron and in the same script 
file make a call to the ImageMagick program 'convert' to set a single color 
transparent:

"convert surface.gif -transparent black surface-transparent.gif"

and then overlay this transparent gif on top of the more frequently made radar 
images with another called to convert in the radar generation shell script:

"convert radar.gif surface-transparent.gif -compose over plot.gif"

where plot.gif is the final product.  This method requires the image/data 
projections be identical or it simply won't look correct - it uses programs 
outside of GEMPAK and will take some experimentation to get right if you choose 
to play around with it.

Michael James
Unidata User Support




> Hi,
> 
> I have a question/problem I am trying to figure out and need some help.  I
> am running a script which creates a radar images of certain areas and
> uploading that to a webpage. I am also creating overlay graphics for the
> same areas (i.e., sfcplot, heights, wind contours, instability, etc).  The
> problem is I have my script creating the overlays every time the radar
> script runs, which is several times an hour.  I only need the overlays once
> an hour.  I am not sure how to create the overlays just once per hour
> without the radar image.  I want to keep it in the radar projection (proj =
> rad).  But how can I make an overlay using GPMAP with the radar image not
> showing?  I just want the background map and then I can overlay it onto the
> radar images I have in my loop.  Right now the way my script reads is I
> create the radar image, then using the same projection and garea...I create
> the overlays using the clear=no option.  Obviously this is not the most
> efficient way to do this....so if you can assist me I would really
> appreciate it. Thanks.
> 
> Kevin
> 


Ticket Details
===================
Ticket ID: WUQ-124584
Department: Support GEMPAK
Priority: Normal
Status: Open