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map projection polygon problem [message #1864]

Wed, 23 March 1994 09:16

ian
Messages: 26
Registered: February 1992

Junior Member

I wish to plot little polygons on a map projection using "polyfill".
This works fine except at the edges of the plot where everything
goes haywire. When half the polygon is "around the back" of the planet
the co-ordinates do not get transformed correctly and the polygon
streaks across to the edge of the screen.

To see the problem try this simple program :

--------------------------------------------

pro poly_plot

; set co-ords for polygon

lat = [0,10,0,-10,0]
lon = [-10,0,10,0,-10]

map_set,0,0,/ortho,/cont,/noborder
loadct,5

; plot polygon
polyfill,lon,lat,color=50

; now put polygon at edge of plot

lon = lon + 85.0

polyfill,lon,lat,color=100

end

------------------------------------------------

If someone has an _uncontrived_ solution please post or e-mail it to me.

Thanks

Ian
ian@denali.gsfc.nasa.gov

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map projection polygon problem

By: ian on Wed, 23 March 1994 09:16

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