[postgis-devel] ST_Buffer in 3D supporting Z

[Sam Hariton]

Regina,

Thanks.  Unfortunately, I'm not going to make it Paris but next time your
on the east coast I'll try to stop by (apparently I completely missed the
event in DC last month).

Is the Paris Sprint likely to result in a decision about
GEOS/Boost/CGAL/PostGIS core/etc.?  Or is it a longer term discussion than
that?


In the meantime, looking through the ticket list, there's a couple tickets
(#430 and #428) that look interesting and I'd like to make a stab at.
 What's the proper etiquette for doing so?

Thanks

 - Sam

On Wed, May 2, 2012 at 4:22 AM, Paragon Corporation <lr at pcorp.us> wrote:

> **
> Sam,
>
> Sam,
> Not to my knowledge.  There are a couple of hurdles we need to jump before
> that step.
>
> The big one:
>
> GEOS is predominantly 2-D engine:  PostGIS buffer and many other functions
> piggy -back on that.
>
> so the big question is whether to expand GEOS to handle new 3d types thus
> deviating more from its JTS roots or use another engine like Boost or CGAL.
> The other option is just to build into PostGIS core, but not sure how much
> effort is involved there.
>
> Olivier is working on much of the 3D stuff and many of the PostGIS core
> dev are having a code sprint in Paris.
>
> I think there is still space left if you want to chat up with them and you
> can make the trip.
>
> http://trac.osgeo.org/postgis/wiki/DevWikiEvent
>
> Hope that helps,
> Regina
> http://www.postgis.us
>
>
>
>
>  ------------------------------
> *From:* postgis-devel-bounces at postgis.refractions.net [mailto:
> postgis-devel-bounces at postgis.refractions.net] *On Behalf Of *Sam Hariton
> *Sent:* Tuesday, May 01, 2012 4:06 PM
> *To:* postgis-devel at postgis.refractions.net
> *Subject:* [postgis-devel] ST_Buffer in 3D supporting Z
>
>  Is anyone looking at adding the ability for st_buffer to keep Z
> coordinates as well for 3-dimensional spaces?  If so, I'd like to help.
>
> The Postgis 2.0 docs state:  This function ignores the third dimension
> (z) and will always give a 2-d buffer even when presented with a
> 3d-geometry.
>
> Right now
>
>  select st_astext(st_buffer(geomfromEWKT('POINT(0 0 0)'),1));
>>
>
> Generates a flat Polygon/Circle of radius 1 (completely dropping the z
> dimension):
>
>  POLYGON((1 0,0.980785280403231 -0.195090322016128,0.923879532511287
> -0.382683432365089,0.831469612302546 -0.555570233019602,0.707106781186548
> -0.707106781186547,0.555570233019603 -0.831469612302545,0.382683432365091
> -0.923879532511286,0.19509032201613 -0.98078528040323,1.61554255216634e-15
> -1,-0.195090322016126 -0.980785280403231,-0.382683432365088
> -0.923879532511288,-0.555570233019601 -0.831469612302546,-0.707106781186546
> -0.707106781186549,-0.831469612302544 -0.555570233019604,-0.923879532511286
> -0.382683432365092,-0.98078528040323 -0.195090322016131,-1
> -3.23108510433268e-15,-0.980785280403231
> 0.195090322016125,-0.923879532511288
>  0.382683432365086,-0.831469612302547 0.555570233019599,-0.70710678118655
> 0.707106781186545,-0.555570233019606 0.831469612302543,-0.382683432365094
> 0.923879532511285,-0.195090322016132 0.98078528040323,-3.73640463187386e-15
> 1,0.195090322016125 0.980785280403231,0.382683432365087
> 0.923879532511288,0.5555702330196 0.831469612302547,0.707106781186545
> 0.70710678118655,0.831469612302544 0.555570233019604,0.923879532511286
> 0.382683432365092,0.98078528040323 0.19509032201613,1 0))
>
> Whereas, if it had z support it should actually generate a Polyhedral
> Surface/Sphere of radius 1 centered on (0 0 0)
>
>  - Sam
>
>
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