H2GIS

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ST_TriangleAspect

Signature

DOUBLE ST_TriangleAspect(GEOMETRY geom);

Description

Returns the aspect value of geom in degrees. Throws an error if geom is not a triangle.

Aspect represents the main slope direction angle compared to the north direction. It can be thought of as the slope direction.

Examples

SELECT ST_TriangleAspect('POLYGON((0 0 0, 3 0 0, 0 3 0, 0 0 0))');
-- Answer: 0.0

SELECT ST_TriangleAspect('POLYGON((0 0 1, 3 0 0, 0 3 1, 0 0 1))');
-- Answer: 90.0

SELECT ST_TriangleAspect('POLYGON((0 0 1, 3 0 1, 0 3 0, 0 0 1))');
-- Answer: 0.0

SELECT ST_TriangleAspect('POLYGON((0 0 1, 3 0 0, 3 3 1, 0 0 1))');
-- Answer: 135.0

SELECT ST_TriangleAspect(
    'POLYGON((0 0 0, 3 0 0, 3 3 0, 0 3 0, 0 0 0))');
-- Exception calling user-defined function:
--     "computeAspect(POLYGON ((0 0, 3 0, 3 3, 0 3, 0 0))):
--     The geometry must be a triangle"
See also