[postgis-users] Angle

[Eduardo Luís Garcia Escovar]

Ezequias Rodrigues da Rocha escreveu:
>
>
> Eduardo Luís Garcia Escovar escreveu:
>> Ezequias Rodrigues da Rocha escreveu:
>>> marco vieira escreveu:
>>>> Ezequias:
>>>>  Look at postgis documentation. azimuth() returns radians, not 
>>>> degrees. You must divide by pi rad and multiply by 180 degrees to 
>>>> obtain 124,9 degrees. Make sure your azimuth is 143,9 by manual 
>>>> calculation using start and end points (make sure you are using the 
>>>> same start and end points).
>>>> Regards.
>>>> -- 
>>>> Marco Vieira
>>>> +55 21 9499-6800
>>>> e-mail: maovieira at gmail.com <mailto:maovieira at gmail.com>   
>>> Marco,
>>>
>>> I did the following:
>>>
>>> DesiredDegree = 180 - ColumnInRad /PI * 1 rad
>>>
>>> Whre 1 rad = 57.29577951
>>>
>>>
>>> Some features works someothers dont.
>>> :-) :-(
>>>
>>> Regards
>>> Ezequias
>>> _______________________________________________
>>> postgis-users mailing list
>>> postgis-users at postgis.refractions.net
>>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>> Ezequias,
>>
>> You should have done like Marco said:
>>
>> DesiredDegree = ColumnInRad/pi( )*180
>>
>> Remember, this result is the azimuth (angle from the north, i.e., 
>> from the y axis, clockwise).
>>
>> Hope this helps,
>> Eduardo
>> _______________________________________________
>> postgis-users mailing list
>> postgis-users at postgis.refractions.net
>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>
> Thank you Eduardo,
>
> Could you see for yourself.
>
> My feature is this one:
>
> MULTILINESTRING ((290635.73828125 9108941.88085938, 290635.94921875 
> 9108941.77929688, 290636.2890625 9108940.7109375, 290636.51953125 
> 9108918.06054688, 290636.509765625 9108917.55078125, 290636.119140625 
> 9108916.06054688, 290635.279296875 9108914.69921875, 290635.146484375 
> 9108914.5703125))
>
>
> The angle my Desktop GIS application says is (OpenJUMP): *91.76 
> degrees* (from up to down)
>
> The Azimuth generated by Postgis is:  3.16325843263936
>
> The angle applying this formula (you suggested):  *181.241357699403 
> degrees
> *
>
> So what is wrong ?
>
>
> Regards ...
Ezequias,

I didn't understand what you meant by "from up to down". Watch the 
picture in attached file, so you can see what is the meaning of the 
azimuth function result.

Regards
Eduardo
-------------- next part --------------
A non-text attachment was scrubbed...
Name: azimuth.PNG
Type: image/png
Size: 4917 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20060706/1fd089f6/attachment.png>