[postgis-devel] SQL Server Denali ShortestLineTo

Wed Dec 8 13:41:30 PST 2010

This is quite cool

I wonder if ST_ShortestLine has inspired...

One quite important difference.
When two geometries intersect I choosed to return a LINESTRING of
zero-length starting and ending in the only, or one of many intersecting
points. My thought was that, it gives additional usability since we get
an intersection point. But MS has chosen to return an empty geometry
instead. Maybe that is more correct, but I still think the zero length
LINESTRING has it's point (hmm, that became more fun than intended :-))

Thanks

Nicklas

On Wed, 2010-12-08 at 11:17 -0500, Paragon Corporation wrote:
> Nicklas,
> 
> Did you see this. 
> 
> SQL Server has released their own ShortestLine function  in their upcoming
> 2011 release except they put a To at the end.
> 
> The answers in PostGIS  are pretty close to theirs.  It's always nice when
> the two systems I use most agree in output. Now I have another system to
> cross compare to.
> 
> http://blogs.msdn.com/b/edkatibah/archive/2010/11/19/a-short-discussion-on-t
> he-shortestlineto-method.aspx 
> 
> I see they also enjoy flaunting their new curved support.  I wonder if they
> have an ST_LongestLine or any kind of 3D support.  I suspect they don't.
> I'm hoping to install Denali sometime soon but  maybe not until the CTP2
> So I can check it out.
> 
> 
> -- PostGIS: 
> SELECT 
> 	ST_AsText(ST_ShortestLine(ST_CurveToLine('CIRCULARSTRING(1.5 1, 1.6
> 1.1, 1.5 2)'::geometry,150),
> 			'POLYGON((2.2 1, 3.2 1, 3.2 2, 2.2 2, 2.2
> 1))'::geometry));
> -- Result: LINESTRING(1.74030584077424 1.50290349279118,2.2
> 1.50290349279118)
> 
> 
> -- SQL Server Denali: 
> DECLARE @c GEOMETRY = 'CIRCULARSTRING(1.5 1, 1.6 1.1, 1.5 2)';
> DECLARE @g GEOMETRY = 'POLYGON((2.2 1, 3.2 1, 3.2 2, 2.2 2, 2.2 1))';
> SELECT @c.ShortestLineTo(@g).ToString(); 
> --Result: LINESTRING (1.740312423743285 1.5, 2.2 1.5)
> 
> 
> -- PostGIS:
> SELECT ST_AsText(ST_ShortestLine('POINT(175346.325596772
> 202579.692494631)'::geometry,
> 'POLYGON((175373.37654079497 202663.47566268593, 175309.02370874584
> 202626.29556666315, 175328.32617276162 202595.99009463936,
> 175328.33046075702 202595.99284664169, 175335.22780476511 202600.4390546456,
> 175335.27100476623 202600.37697464228, 175335.33071676642
> 202600.29115064442, 175342.50012476742 202604.9433106482, 175343.06434877217
> 202605.3093906492, 175355.01686077565 202585.1888146326, 175355.22690878063
> 202584.8352146335, 175346.57487677038 202579.83649462834, 175350.90825277567
> 202572.54171062633, 175351.08706877381 202572.240654625, 175346.8919967711
> 202569.81697462127, 175345.81129277498 202569.19259062409,
> 175345.50646077097 202569.01646262407, 175352.43746877462
> 202558.13460661471, 175378.08418879658 202517.86843058839,
> 175378.47298879176 202517.2579985857, 175387.97513280064 202521.08609458804,
> 175392.46217280626 202523.75739059225, 175415.91702082008
> 202537.72103860229, 175429.48124483228 202545.79636660591,
> 175439.01698883623 202552.97799861059, 175438.9791008383 202553.04180661216,
> 175425.85634882748 202575.13236662746, 175373.37654079497
> 202663.47566268593), (175387.31574080139 202542.21063860506,
> 175387.92713280022 202542.56340660527,175385.82249280065 202546.25569460541,
> 175392.09526080638 202549.76961461082, 175391.75484480709
> 202550.37588660792, 175400.52566081286 202555.39905461296,
> 175402.95503681153 202551.16513460875, 175403.52956481278
> 202551.49115061015, 175408.33698881418 202543.07399860397, 175392.2850208059
> 202533.85300659761, 175387.31574080139 202542.21063860506))'::geometry))
> 
> -- Result: LINESTRING(175346.325596772 202579.692494631,175346.57487677
> 202579.836494628)
> 
> -- SQL Server Denali:
> DECLARE @h GEOMETRY = 'POINT(175346.325596772 202579.692494631)';
> 
> DECLARE @g GEOMETRY = 'POLYGON((175373.37654079497 202663.47566268593,
> 175309.02370874584 202626.29556666315, 175328.32617276162
> 202595.99009463936, 175328.33046075702 202595.99284664169,
> 175335.22780476511 202600.4390546456, 175335.27100476623 202600.37697464228,
> 175335.33071676642 202600.29115064442, 175342.50012476742 202604.9433106482,
> 175343.06434877217 202605.3093906492, 175355.01686077565 202585.1888146326,
> 175355.22690878063 202584.8352146335, 175346.57487677038 202579.83649462834,
> 175350.90825277567 202572.54171062633, 175351.08706877381 202572.240654625,
> 175346.8919967711 202569.81697462127, 175345.81129277498 202569.19259062409,
> 175345.50646077097 202569.01646262407, 175352.43746877462
> 202558.13460661471, 175378.08418879658 202517.86843058839,
> 175378.47298879176 202517.2579985857, 175387.97513280064 202521.08609458804,
> 175392.46217280626 202523.75739059225, 175415.91702082008
> 202537.72103860229, 175429.48124483228 202545.79636660591,
> 175439.01698883623 202552.97799861059, 175438.9791008383 202553.04180661216,
> 175425.85634882748 202575.13236662746, 175373.37654079497
> 202663.47566268593), (175387.31574080139 202542.21063860506,
> 175387.92713280022 202542.56340660527,175385.82249280065 202546.25569460541,
> 175392.09526080638 202549.76961461082, 175391.75484480709
> 202550.37588660792, 175400.52566081286 202555.39905461296,
> 175402.95503681153 202551.16513460875, 175403.52956481278
> 202551.49115061015, 175408.33698881418 202543.07399860397, 175392.2850208059
> 202533.85300659761, 175387.31574080139 202542.21063860506))';
> 
> DECLARE @sl GEOMETRY = @h.ShortestLineTo(@g);
> 
> SELECT @sl.STAsText();
> --Result: LINESTRING(175346.325596772 202579.692494631, 175346.57487677038
> 202579.83649462834) 
> 
> Thanks,
> Regina
> 
> 
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