[postgis-devel] RFC - Orientation checking and forcing functions

[Regina Obe]

Dan,

 

You should really just call it - ST_ForcePolygonsClockwiseExteriorRingAndCounterClockwiseInteriorRings

 

strk just loves to type :)

 

He may ask you to remove the ST_ though.

 

Sorry couldn't resist.

 

From: postgis-devel [mailto:postgis-devel-bounces at lists.osgeo.org] On Behalf Of Daniel Baston
Sent: Wednesday, February 08, 2017 3:35 PM
To: PostGIS Development Discussion <postgis-devel at lists.osgeo.org>
Subject: Re: [postgis-devel] RFC - Orientation checking and forcing functions

 

I'll try to see if I can come up with a less ambiguous name, without resorting to ST_ForcePolygonsClockwiseExteriorRingAndCounterClockwiseInteriorRings, but I'll also note that the proposed terminology has been used by PostGIS internally since 2010:

 

https://github.com/postgis/postgis/commit/2d07d7eb59d2bb8db9d4773cd84619cd696bc471

 

Dan

 

 

On Wed, Feb 8, 2017 at 3:17 PM, Sandro Santilli <strk at kbt.io <mailto:strk at kbt.io> > wrote:

On Wed, Feb 08, 2017 at 03:05:33PM -0500, Daniel Baston wrote:
> The idea was that adding functions with different names would be helpful,
> because "RHR" and "LHR" mean different things to different people (and
> therefore don't mean much of anything.)

In PostGIS "RHR" and "LHR" have well-documented meaning, right ?

> See, for example, the fourth bullet under
> https://tools.ietf.org/html/rfc7946#section-3.1.6

The Wikipedia definition of the rule is about 3d and implies a 3D space,
which is not always the case within PostGIS geometries:
https://en.wikipedia.org/wiki/Right-hand_rule

If you find a name/label which means the same to everybody I'll be
happy to see a wrapper function using it. "Clockwise" for a polygon
with holes doesn't seem to be unambiguous to me (it could for example
mean "all rings are clockwise"...)


--strk;
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