ST_VariableBuffer
Signatures
GEOMETRY ST_VariableBuffer(GEOMETRY geom, DOUBLE startDistance, DOUBLE endDistance);
Description
Create a buffer polygon along a LINESTRING (geom) with the buffer width interpolated between a start distance (startDistance) and an end distance (endDistance), both given in projection units.
Warning
This function only works with LINESTRING
Warning
This function remove Z, M or ZM dimension of input coordinates
Example
SELECT ST_VariableBuffer('LINESTRING (1 1, 6 6)', 1, 2);
-- Answer: POLYGON ((0.2 1.6, 4.4 7.2, 4.585786437626905 7.414213562373095, 4.888859533960796 7.662939224605091, 5.234633135269821 7.847759065022574, 5.609819355967744 7.961570560806461, 6 8, 6.390180644032257 7.961570560806461, 6.765366864730179 7.847759065022574, 7.111140466039204 7.662939224605091, 7.414213562373095 7.414213562373095, 7.662939224605091 7.111140466039204, 7.847759065022574 6.765366864730179, 7.961570560806461 6.390180644032257, 8 6, 7.961570560806461 5.609819355967743, 7.847759065022574 5.234633135269821, 7.662939224605091 4.888859533960796, 7.2 4.4, 1.6 0.2, 1.5555702330196017 0.1685303876974545, 1.38268343236509 0.0761204674887134, 1.1950903220161284 0.0192147195967696, 1 0, 0.8049096779838714 0.0192147195967697, 0.6173165676349097 0.0761204674887135, 0.4444297669803978 0.1685303876974548, 0.2928932188134523 0.2928932188134525, 0.1685303876974545 0.444429766980398, 0.0761204674887132 0.6173165676349104, 0.0192147195967696 0.8049096779838716, 0 1, 0.0192147195967696 1.1950903220161286, 0.0761204674887133 1.3826834323650898, 0.1685303876974547 1.5555702330196022, 0.2 1.6))
Case with Z, M or ZM dimension
In this example, we have a LINESTRING Z
SELECT ST_VariableBuffer('LINESTRING Z(1 1 0, 6 6 3)', 1, 2);
As a result, we obtain a 2D POLYGON
POLYGON ((0.2 1.6, 4.4 7.2, 4.585786437626905 7.414213562373095, 4.888859533960796 7.662939224605091, 5.234633135269821 7.847759065022574, 5.609819355967744 7.961570560806461, 6 8, 6.390180644032257 7.961570560806461, 6.765366864730179 7.847759065022574, 7.111140466039204 7.662939224605091, 7.414213562373095 7.414213562373095, 7.662939224605091 7.111140466039204, 7.847759065022574 6.765366864730179, 7.961570560806461 6.390180644032257, 8 6, 7.961570560806461 5.609819355967743, 7.847759065022574 5.234633135269821, 7.662939224605091 4.888859533960796, 7.2 4.4, 1.6 0.2, 1.5555702330196017 0.1685303876974545, 1.38268343236509 0.0761204674887134, 1.1950903220161284 0.0192147195967696, 1 0, 0.8049096779838714 0.0192147195967697, 0.6173165676349097 0.0761204674887135, 0.4444297669803978 0.1685303876974548, 0.2928932188134523 0.2928932188134525, 0.1685303876974545 0.444429766980398, 0.0761204674887132 0.6173165676349104, 0.0192147195967696 0.8049096779838716, 0 1, 0.0192147195967696 1.1950903220161286, 0.0761204674887133 1.3826834323650898, 0.1685303876974547 1.5555702330196022, 0.2 1.6))