[postgis-devel] [PostGIS] #892: Smarter linear location (for ST_Line_Interpolate_Point, ST_Line_Substring, ST_Line_Locate_Point)

[PostGIS]

#892: Smarter linear location (for ST_Line_Interpolate_Point, ST_Line_Substring,
ST_Line_Locate_Point)
-------------------------+--------------------------------------------------
 Reporter:  strk         |       Owner:  pramsey      
     Type:  enhancement  |      Status:  new          
 Priority:  medium       |   Milestone:  PostGIS 2.0.0
Component:  postgis      |     Version:  trunk        
 Keywords:               |  
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 ST_LocatePoint returns a value which you can't easily convert to a vertex
 number. This isn't helpful if what you're looking for is a substring
 formed by pre-existing vertices rather than formed by arbitrarily
 interpolated points.

 In turn, re-using existing vertices is required to avoid introducing
 coordinates drifts when willing to analize subportions of lines.

 GEOS/JTS, for comparison, uses a pair of (SEG_NUM/SEG_FRACTION)
 representing in turn the segment index and the fraction of next segment.

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/892>
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