[postgis-users] Use of Azimuth Function

[Matthew Pulis]

Hi,

 

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
gid=45305),

(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
numgeometries(the_geom)

 

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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