Re: How to plot outline of overlapping circles

With gmtspatial -Sc you can compute the union of the circles about each 
transmitter. This is essentially what you want to do.

Joaquim

> Dear List,
>
> I'm plotting circles depicting the same distance around a given 
> coordinate representing the range of a VHF transmitter. While these 
> VHF transmitter sites are usually quite close together to get a 
> seamless coverage, there are obviously no sites in the middle of the 
> sea. I'm interested in the visual representation of the coverage. I'm 
> not interested in the exact coverage of each and every single 
> transmitter, just in the boundary where the coverage ends.
>
> Currently I'm plotting the coverage with the build in ellipse symbol 
> (-SE) getting overlapping circles (see output.jpg; the thick white 
> lines). I'd like to reduce the circles to the part crudely highlighted 
> in red in desired_result.jpg representing the outer boundary of the 
> covered area and get rid of any parts laying inside the covered area.
>
> I have currently no idea on how to achieve the desired result. Any 
> nudge in the right direction is greatly appreciated.
>
> All the best,
> Kristof Koch
>
> I'm currently using
>
> gmt - Version 5.1.0 (r12452) [64-bit] on
> Ubuntu 12.04.3 LTS (GNU/Linux 2.6.32-042stab081.5 x86_64)
>
> The part of the script generating the white circles in the attached 
> images:
>
> cat > $WORK_DIR/com_site.txt << END
> -22.606 63.985 0 1111.2 1111.2
> -19 63.4 0 1111.2 1111.2
> -7.588 62.107 0 1111.2 1111.2
> END
>
> psxy \
> $WORK_DIR/com_site.txt \
> -J -R \
> -SE -Wfat,white \
> -K -O \
> >> $FILE
>
>
>
>
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