Table of Contents
A temporal rigid geometry (trgeometry) is a static 2D reference geometry, typically a polygon describing the shape of a moving body, paired with a temporal pose (tpose) describing how that geometry translates and rotates over time. The materialised geometry at time t is the reference geometry rotated and translated according to the pose interpolated at t.
This is the natural representation for moving objects whose shape matters, not just their position. The motivating example is AIS maritime traffic, where each ship's hull (a pentagon derived from the antenna offsets A, B, C, D) follows a pose path defined by lat/lon and heading reports. The materialised geometry at any instant is the actual ship outline at that moment.
The trgeometry type builds on Chapter 13, Temporal Poses. Most accessor, comparison, topological, position, and indexing operators have the same shape as the corresponding tpose functions; this chapter covers the trgeometry-specific surface, pose-to-shape materialisation, traversed area, materialised distance, and spatial restrictions on the centroid trajectory.
A trgeometry literal pairs a reference geometry with a temporal pose. The reference geometry comes first, separated from the pose by a semicolon; the pose follows the standard tpose syntax (instant, sequence, or sequence set).
SELECT trgeometry 'Polygon((0 0,1 0,1 1,0 1,0 0));Pose(Point(0 0), 0.5)@2001-01-01';
SELECT trgeometry 'Polygon((0 0,1 0,1 1,0 1,0 0));{Pose(Point(0 0), 0.0)@2001-01-01, Pose(Point(5 0), 0.5)@2001-01-02, Pose(Point(0 0), 0.0)@2001-01-03}';
SELECT trgeometry 'Polygon((0 0,1 0,1 1,0 1,0 0));[Pose(Point(0 0), 0.0)@2001-01-01, Pose(Point(10 0), 1.5)@2001-01-02]';
SELECT trgeometry 'Polygon((0 0,1 0,1 1,0 1,0 0));{[Pose(Point(0 0), 0.0)@2001-01-01, Pose(Point(5 0), 0.0)@2001-01-02], [Pose(Point(0 0), 0.0)@2001-01-04, Pose(Point(2 0), 0.0)@2001-01-05]}';
The reference geometry can be any 2D polygon or polyhedral surface. The pose interpolation is linear in translation and angular-shortest-path in rotation. SRIDs are inherited from the reference geometry and the pose; they must agree.
An SRID can be specified for a trgeometry either at the begining of the literal or before the reference geometry as shown below.
SELECT trgeometry 'SRID=25832;Polygon((0 0,1 0,1 1,0 1,0 0));Pose(Point(0 0), 0.5)@2001-01-01'; SELECT trgeometry 'Polygon((0 0,1 0,1 1,0 1,0 0));SRID=25832;Pose(Point(0 0), 0.5)@2001-01-01';
Step interpolation can also be specified in the same way as for other temporal types:
SELECT trgeometry 'Interp=Step;Polygon((0 0,1 0,1 1,0 1,0 0));[Pose(Point(0 0), 0.0)@2001-01-01, Pose(Point(10 0), 0.0)@2001-01-02]';
The standard wire formats are supported.
Return the Well-Known Text (WKT) representation
asText({trgeometry,trgeometry[]} [, maxdecimaldigits int=15]) → text
SELECT asText(trgeometry 'Polygon((1 1,2 2,3 1,1 1));Pose(Point(1.123456789 1.123456789), 0.5)@2000-01-01', 6); -- POLYGON((1 1,2 2,3 1,1 1));Pose(POINT(1.123457 1.123457),0.5)@2000-01-01
Return the Extended Well-Known Text (EWKT) representation, prefixed with the SRID
asEWKT({trgeometry,trgeometry[]} [, maxdecimaldigits int=15]) → text
SELECT asEWKT(trgeometry 'SRID=25832;Polygon((1 1,2 2,3 1,1 1));Pose(Point(1 1),0.5)@2000-01-01'); -- SRID=25832;POLYGON((1 1,2 2,3 1,1 1));Pose(POINT(1 1),0.5)@2000-01-01
Return the Moving Features JSON representation
asMFJSON(trgeometry [, options int=0 [, flags int=0 [, maxdecimaldigits int=15]]]) → text
SELECT asMFJSON(trgeometry 'Polygon((0 0,1 0,1 1,0 1,0 0));Pose(Point(0 0),0)@2001-01-01');
Return the Extended Well-Known Binary (EWKB) representation
asEWKB(trgeometry [, endian text]) → bytea
Companion asHexEWKB returns the same bytes as a hex-encoded text.
SELECT length(asEWKB(trgeometry 'Polygon((0 0,1 0,1 1,0 1,0 0));Pose(Point(1 1), 0.5)@2001-01-01')); -- 130 -- The bytes round-trip through the matching input function. SELECT asText(trgeometryFromHexEWKB(asHexEWKB(trgeometry 'Polygon((0 0,1 0,1 1,0 1,0 0));Pose(Point(1 1), 0.5)@2001-01-01'))); -- POLYGON((0 0,1 0,1 1,0 1,0 0));Pose(POINT(1 1),0.5)@2001-01-01
Each output format has a companion parser:
trgeometryFromText(text) → trgeometry
trgeometryFromEWKT(text) → trgeometry
trgeometryFromMFJSON(text) → trgeometry
trgeometryFromEWKB(bytea) → trgeometry
trgeometryFromHexEWKB(text) → trgeometry
SELECT asText(trgeometryFromEWKT('SRID=4326;Polygon((0 0,1 0,1 1,0 1,0 0));
Pose(Point(1 1), 0.5)@2001-01-01'));
-- POLYGON((0 0,1 0,1 1,0 1,0 0));Pose(POINT(1 1),0.5)@2001-01-01
SELECT asText(trgeometryFromHexEWKB(asHexEWKB(trgeometry 'Polygon((0 0,1 0,1 1,0 1,0 0));Pose(Point(1 1), 0.5)@2001-01-01')));
-- POLYGON((0 0,1 0,1 1,0 1,0 0));Pose(POINT(1 1),0.5)@2001-01-01