Stereographic map with small extension

Q&A
1

Hi,

I try to reproduce a map I’ve seen some times ago …
It is a map of the artic region (above 65N) with just Greenland added outside the boundaries (something like “unclip” [-N?])

I tried several things including this :

gmt begin arctic_map png
    gmt coast -R0/360/65/90 -JS0/90/15c -Dh -Wthinnest,black -Ir/faint,lightblue
    gmt coast -EGL,IS+c -R0/360/55/90 -JS0/90/15c 
    gmt coast -Dh -Wthinnest,red -Ir/faint,lightblue
    gmt coast -Q
gmt end show

As you can see, I have a scaling problem…

Is there a way to achieve that without resort to mapproject ? (if it even works)

Thanks

2

You need to use map scale rather than map width and so some calculations, e.g.

gmt begin arctic_map png
	W1=$(gmt mapproject -R0/360/65/90 -Js0/90/72/1:25000000 -Ww)
	H1=$(gmt mapproject -R0/360/65/90 -Js0/90/72/1:25000000 -Wh)
	W2=$(gmt mapproject -R0/360/55/90 -Js0/90/72/1:25000000 -Ww)
	H2=$(gmt mapproject -R0/360/55/90 -Js0/90/72/1:25000000 -Wh)
	dx=$(gmt math -Q $W1 $W2 SUB 2 DIV =)
	dy=$(gmt math -Q $H1 $H2 SUB 2 DIV =)
    gmt coast -R0/360/65/90 -Js0/90/72/1:25000000 -Dh -Wthinnest,black -Ir/faint,lightblue -B0
    gmt coast -EGL,IS+c -R0/360/55/90 -X${dx} -Y${dy}
    gmt coast -Dh -Wthinnest,red -Ir/faint,lightblue
    gmt coast -Q
gmt end show
1 Like
3

Thank you @pwessel !

It’s astonishingly simpler than what I expected (mapproject module seems scary).

4

Great! Could you share your map (here or in showcase). I would like to see it.

5

Sure,

I’ll try to add a little animation first (movie) then I’ll make the showcase :wink:

update // @Esteban82 : done

1 Like