[gradsusr] Creating "Lines" Shapefiles

[Jennifer Adams]

Hi, Stephen --
Brian and I are glad to hear you are successfully using the new  
shapefile interface. Unfortunately, what you are asking for is not in  
our development plans. The graphical elements created with the 'draw'  
command are not based on gridded or station data in a lon/lat spatial  
domain, but on the page coordinates in an X,Y domain. There is no  
existing mechanism to convert elements from the graphics metafile  
buffer back into a lat/lon environment and then output a shapefile.

There may be some other software tools out there to create shapefiles  
based on user-defined coordinates, but it might not be such a  
difficult stand-alone program to write yourself. Start by looking at  
the examples in the shapefile library's source code.

--Jennifer





On Oct 25, 2010, at 11:04 AM, Stephen McMillan wrote:

> I think it's a great addition to have both the draw- and create- 
> shapefiles capabilities in GrADS now, and have successfully done  
> both from the latest release.
>
> As I understand the online documentation, shapefiles can be created  
> using only the "display" command, and that "the shape types  
> currently supported are points and lines...."  with lines being  
> contour lines.  Are there any plans to support shapefile creation  
> using the "draw" command, such as for creating straight line  
> segments or polygons, as it does for drawing shapefiles?
>
> Perhaps the developers or another user knows of a way to write  
> shapefiles derived from drawn (not displayed) map features.  The  
> only way I can think of is to somehow incorporate the desired line/ 
> polygon features within a gridded file, perhaps similar to the way  
> "lat" and "lon" are done, except crossing lat/lon lines.
>
> I am using the OpenGrADS version 2.0.a9.oga.1 on a Windows XP.
>
> Thanks
> Stephen McMillan
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--
Jennifer M. Adams
IGES/COLA
4041 Powder Mill Road, Suite 302
Calverton, MD 20705
jma at cola.iges.org



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