[fdo-internals] Motion: Vote on FDO RFC 38 - SHP multi-polygons

[Dan Stoica]

Hi Frank,

> Does the FDO SHP driver ensure proper winding order for inner and outer rings when writing shapefiles?

No, it doesn't. We've discussed here this issue and apparently the best way to do it is via a new capability that tells the preferred ring orientation.

But this will not solve the problem of reading existing shapes (created via FDO or not) since the orientation is not reliable.

Thanks,
Dan.


-----Original Message-----
From: fdo-internals-bounces at lists.osgeo.org [mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Frank Warmerdam
Sent: Tuesday, September 08, 2009 8:09 AM
To: FDO Internals Mail List
Subject: Re: [fdo-internals] Motion: Vote on FDO RFC 38 - SHP multi-polygons


> There were no further comments on this RFC: 
> http://trac.osgeo.org/fdo/wiki/FDORfc38 - Multi-polygon support for SHP.
> 
>  
> 
> I would like to motion a vote to accept this RFC.

+1

---

On final review I was somewhat concerned about the comment "On input of
geometry, there is no further processing needed as the current code will
save all input loops without checking whether they are outer or inner."

There is a particular winding order expected in properly produced shapefiles.
Does the FDO SHP driver ensure proper winding order for inner and outer
rings when writing shapefiles?

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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