Mercurial > gemma

comparison schema/isrs_functions.sql @ 1811:c21f72775f6b

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Fix numerical problems in stretch area generation
author Tom Gottfried <tom@intevation.de>
date Tue, 15 Jan 2019 19:46:41 +0100
parents 50548a6df009
children f9f1babe52ae
comparison
equal deleted inserted replaced
1810:7ee9bdaac336 1811:c21f72775f6b
63 FROM axis) AS lines, 63 FROM axis) AS lines,
64 (SELECT ST_Collect(from_point.geom, to_point.geom) AS pts 64 (SELECT ST_Collect(from_point.geom, to_point.geom) AS pts
65 FROM from_point, to_point) AS points 65 FROM from_point, to_point) AS points
66 WHERE ST_Covers(ST_Buffer(lines.line, 0.0001), points.pts)), 66 WHERE ST_Covers(ST_Buffer(lines.line, 0.0001), points.pts)),
67 axis_substring AS ( 67 axis_substring AS (
68 -- Use linear referencing to clip axis between distance marks 68 -- Use linear referencing to clip axis between distance marks.
69 SELECT ST_LineSubstring( 69 -- Simplification is used to work-around the problem, that
70 -- ST_LineSubstring might generate very small line segments at an
71 -- end of the resulting linestring, that significantly differ from
72 -- the direction of the input linestring due to finite precision
73 -- of the calculation. The generated small segment of the
74 -- resulting line leads to unexpected results of the buffer with
75 -- endcap=flat in the CTE below.
76 SELECT ST_SimplifyPreserveTopology(ST_LineSubstring(
70 axis_segment.line, 77 axis_segment.line,
71 ST_LineLocatePoint(axis_segment.line, from_point.geom), 78 ST_LineLocatePoint(axis_segment.line, from_point.geom),
72 ST_LineLocatePoint(axis_segment.line, to_point.geom) 79 ST_LineLocatePoint(axis_segment.line, to_point.geom)
73 ) AS line 80 ), 0.0001) AS line
74 FROM axis_segment, from_point, to_point), 81 FROM axis_segment, from_point, to_point),
75 range_area AS ( 82 range_area AS (
76 -- Create a buffer around the clipped axis, as large as it could 83 -- Create a buffer around the clipped axis, as large as it could
77 -- potentially be intersecting with the area polygon that 84 -- potentially be intersecting with the area polygon that
78 -- intersects with the clipped axis. Get the intersection of that 85 -- intersects with the clipped axis. Get the intersection of that