PostGIS Cookbook - Second Edition

How it works...

We have been using a self-spatial join of a linear PostGIS spatial layer to find intersections generated by the features of that layer.

To generate the self-spatial join, we used the ST_Intersects function. This way, we found that all of the features have at least an intersection in their respective geometries.

In the same self-spatial join context, we found out the intersections, using the ST_Intersection function.

The problem is that the computed intersections are not always single points. In fact, two intersecting lines can produce the origin for a single-point geometry (ST_Point) if the two lines just intersect once. But, the two intersecting lines can produce the origin for a point collection (ST_MultiPoint) or even a ...