[postgis-users] Use of Azimuth Function

Matthew Pulis mpulis at gmail.com
Wed Feb 13 09:58:34 PST 2008



I need to find the angle of elevation from one point to the previous point
in a route.


I have come up with this query :


select azimuth (


(select endpoint((geometryn ( the_geom,1))) from streets_3d where

(select startpoint((geometryn(the_geom,1)))  from streets_3d where gid=3800)



And the result I got is : 2.26067325611865


However when I tried to work it normally, using the TANGENT rule I got this
result : 0.689 radians.


Can someone please point out what I did wrong?


This is the endpoint of gid 45305 : "POINT(637677.049535278 239825.913222565
138.439494012 0)"

This is the startpoint of gid 3800 : "POINT(655579.694091448
225053.918041725 88.700036976 0)"


Both geometries are MULTILINESTRING and have 1 INESTRING according to


Does the z affect the angle? I tried it on the same table without the 3D
aspect and I got the same results as I got from table streets_3d.


Any help is much appreciated


Thanks and regards


Matthew Pulis




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