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I have two LineString and I want take their intersection. I don't understand why PostGIS doesn't give me the correct answer.

select ST_Intersection(st_geomfromtext('LINESTRING(2.9363672 36.769075,2.9364605 36.7688602,2.9368677 36.7673497,2.937295 36.7665308,2.93756649563816 36.7660571843283)', 4326), 
                   st_geomfromtext('LINESTRING(2.93667144830571 36.7680776916115,2.9368677 36.7673497,2.937295 36.7665308,2.9377967 36.7656556)', 4326))

It's clear that the real intersection is not what gives PostGIS.

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  • 1
    What do you get and what do you suppose to get?
    – user30184
    Apr 3 '21 at 11:43
  • It give me small part of real intersection. You can test it and see.
    – عبد القادر كعوان
    Apr 3 '21 at 12:58
  • Welcome to GIS SE! We're a little different from other sites; this isn't a discussion forum but a Q&A site. Your questions should as much as possible describe not just what you want to do, but precisely what you have tried and where you are stuck trying that. Please check out our short tour for more about how the site works
    – Ian Turton ♦
    Apr 3 '21 at 13:06
  • Thank you, But I think having problem with one function in postgis, this is why I asked for it.
    – عبد القادر كعوان
    Apr 3 '21 at 13:52
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Finally, I find the solution. Before comparing geometries in PostGIS, we must put them in same plan with "st_snap". Then, my query must be like this :

select ST_Intersection(
   st_snap(st_geomfromtext('LINESTRING(2.9363672 36.769075,2.9364605 36.7688602,2.9368677 36.7673497,2.937295 36.7665308,2.93756649563816 36.7660571843283)', 4326), 
           st_geomfromtext('LINESTRING(2.93667144830571 36.7680776916115,2.9368677 36.7673497,2.937295 36.7665308,2.9377967 36.7656556)',4326),0.0000001),
   st_geomfromtext('LINESTRING(2.93667144830571 36.7680776916115,2.9368677 36.7673497,2.937295 36.7665308,2.9377967 36.7656556)', 4326))
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