[postgis-users] How to define and select ends of river courses depicted by polygons?

[Shaozhong SHI]

In PostGIS, we can select start and end points of a line.

However, in order to show more details of river courses, polygons are used
to depict linear features.

How to define and select their end points?

Can anyone enlighten me?

Regards,

Shao
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