I have a linestring which crosses itself, like in the picture below. There isn't any vertice at the crossing.
It is a MultiLinestring, so when I want to get the startpoint, the endpoint, or the azimuth (for instance), I get an empty result. I tried to use ST_Linemerge, but for the same result. I think the problem come from the fact that this linestring is crossing itself since I don't have that problem with the linestrings (in the same table) which don't cross themselves.
I am trying to get xmin, xmax, azimuth... in order to establish a process for an atlas in QGIS. I would prefer to manage that in PostGIS, do you have any idea on the way to go?
In my experience these self-crossing linestrings are a big source of problems (with ST_Dump for example), problems that nor me nor my colleagues ever managed to solve, so any insight would be very welcome.