PLPGSQL Function to cross the dateline

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PLPGSQL Function to cross the dateline

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Last edited Feb 10, 2014

Created on Feb 4, 2014

This example provides a PL/pgSQL function, `AXH_CrossDateLine`, that constructs a valid geometry for a line crossing the antimeridian in Web Mercator projection (EPSG:3857). It takes two input points, identifies the western and easternmost coordinates, and calculates the latitude where the line intersects the projection’s edge using proportional math. The function then returns a multi-part line by splitting the path at the ±20037508.34 meter boundaries, using PostGIS functions like `ST_MakeLine`, `ST_SetSRID`, and `ST_Collect`. This utility ensures dateline-crossing routes render correctly in web maps.

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