Thank you Andrea, it works!!
recapitulation for others user: if you have 2 point and you need one segment
of the nearest layer
// select nearest layer (if multilinestring use ST_LineMerge(pt.the_geom) AS
pt_geom)
SELECT pt.the_geom AS pt_geom, pt.gid AS pt_id
FROM line_layer pt
WHERE ST_DWithin(pt.the_geom, ST_GeomFromText('LINESTRING(1708654.405649647
4776470.575996869,1708894.1262744942 4776331.757517987)'), 10.0)
// SNAP points on the prev layer foreach point
SELECT ST_AsText(ST_Line_Interpolate_Point( pt_geom,
ST_Line_Locate_Point(pt_geom,
ST_GeomFromText('POINT(1708654.405649647 4776470.575996869)'))
))
SELECT ST_AsText(ST_Line_Interpolate_Point( pt_geom,
ST_Line_Locate_Point(pt_geom,
ST_GeomFromText('POINT(1708894.1262744942 4776331.757517987)'))
))
// get segment from two prev points
SELECT ST_AsText(ST_Line_Substring(pt_geom,
ST_Line_Locate_Point(pt_geom,ST_GeomFromText('POINT(1708673.98843775 4776461.03369148)')),
ST_Line_Locate_Point(pt_geom,ST_GeomFromText('POINT(1708940.5269833
4776286.80931636)')))
)
Now my problem is: if the "select nearest layer" return 2 or more layers? It's same solution? Or I
need to intersect the resultant layer?
thanks again
Il 11/09/10 18.30, Andrea Peri ha scritto:
Thanks, I tried this function, but it returns all points and I need only that
are inside a segment between two points.
ie:
MULTILINESTRING((0 0,1 1,1 2,2 3,3 2,5 4))
POINT(1 1) POINT(3 2)
I want LINESTRING(1 1,1 2,2 3,3 2)
Perhaps something like this is like for you.
ST_Line_Substring(geometry_line,ST_Line_Locate_Point(geometry_line,geometryPoint_start),ST_Line_Locate_Point(geometry_line,geometryPoint_end))
where
geometryPoint_start = ST_GeomFromText('POINT(1,1)');
geometryPoint_end = ST_GeomFromText('POINT(3,2)');
--
-----------------
Andrea Peri
. . . . . . . . .
qwerty àèìòù
-----------------
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