[gradsusr] GrADS shapefile rings caveat

[Michael Mase]

Just to clarify - the main reason that this is a problem is it prohibits
applying algorithms like basis spline to modify/smooth the geometries, so
it would be fantastic to find a workaround.

On Sat, Sep 16, 2017 at 12:32 PM Michael Mase <masester at gmail.com> wrote:

> Thanks, Jennifer. That makes sense. I'm wondering if there is a practical
> way outside of GrADS to transform the exported shapefile to this desired
> result. If you have any ideas, I would love to hear them. I may dig in to
> see if I can find a practical way to do this and perhaps it could be added
> as a hint to the documentation if you so wish.
>
> Thanks again!
>
> Mike
>
> On Sat, Sep 16, 2017 at 11:24 AM Jennifer M Adams <jadams21 at gmu.edu>
> wrote:
>
>> Hi, Mike —
>> It is likely that the caveat will remain a feature in GrADS — even if we
>> did not draw the inner rings, filling in the outer ring will always cover
>> the entire area, and the area inside the inner rings could not be undrawn.
>> A corrollary of the caveat is that shapefiles exported from GrADS will
>> never have inner rings — the shading algorithm is specifically designed to
>> avoid this problem. It would certainly have been easier to export closed
>> contours as polygons with inner rings, but then GrADS would not have been
>> able to display its own shapefiles properly.
>>
>> The workaround for the caveat is to rewrite the shapefile so that the
>> polygons do not have inner rings; the boundary points would include the
>> inner and outer rings with an overlapping line that connects the two rings.
>> —Jennifer
>>
>>
>> > On Sep 15, 2017, at 11:10 AM, Michael Mase <masester at gmail.com> wrote:
>> >
>> > Hi there,
>> >
>> > Just wondering if the latest GrADS version supports exporting
>> shapefiles with inner rings now or if there are plans to support this in
>> the future?
>> >
>> > Thanks,
>> > Mike
>> > _______________________________________________
>> > gradsusr mailing list
>> > gradsusr at gradsusr.org
>> > http://gradsusr.org/mailman/listinfo/gradsusr
>>
>> --
>> Jennifer Miletta Adams
>> Center for Ocean-Land-Atmosphere Studies (COLA)
>> George Mason University
>>
>>
>>
>>
>> _______________________________________________
>> gradsusr mailing list
>> gradsusr at gradsusr.org
>> http://gradsusr.org/mailman/listinfo/gradsusr
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://gradsusr.org/pipermail/gradsusr/attachments/20170916/2c33b80d/attachment.html