[gradsusr] Better polygon shapefiles

[Michael Mase]

Thanks, Jennifer! This is very helpful. I'm interested to learn more why
GrADS can't export with rings. I've used degrib a few times and it seems to
do this beautifully. However, it relies on the GRIB data being in the final
state - which makes GrADS more appealing.
On Mon, Jan 18, 2016 at 3:52 PM Jennifer M Adams <jadams21 at gmu.edu> wrote:

> The polygons in a Grads-generated shapefile conform to the ESRI
> specifications (
> https://www.esri.com/library/whitepapers/pdfs/shapefile.pdf) but have an
> additional constraint so that GrADS will render them properly: no rings,
> a.k.a. polygons within other polygons, a.k.a. “donuts". For this reason,
> the filled contours are are sliced up into odd-looking polygons that you
> can see clearly if you draw them individually, or with an outline color
> that does not match the fill color. There is nothing to be done about that
> on the GrADS side. There are probably some GIS tools that will merge
> polygons, but if you want a smooth-looking and outlined filled contour
> plot, write out the polygons and line contours into two separate shapefiles
> and overlay them. —Jennifer
>
>
> On Jan 18, 2016, at 2:08 PM, Michael Mase <masester at gmail.com> wrote:
>
> Exporting shapefiles works fantastic when using lines. However, when you
> export using polygons, you get very broken and disconnected shapes
>
>
> Does anyone have any advice on writing/exporting solid shapefiles that
> have joined multi-polygons (for each contour region; each temperature
> interval, for example)?
>
> It would be nice if each polygon layer represented each interval on the
> map and was nicely joined and closed properly.
>
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> --
> 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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