[postgis-users] why st_isclosed() is false?

[Ralf Suhr]

Hallo Birgit,

your Multilinestring can not be convert to a valid linestring. ST_Linemerge 
give not a Linestring.
The parts 2 and 3 have the same start and endpoint

Gr
Ralf

Am Montag 17 Januar 2011, 15:51:49 schrieb Birgit Laggner:
>   Dear list,
> 
> perhaps somebody could clear things for me:
> 
> If I run the query below, the result is "false". But I don't understand
> why. I always thought, as long as there exists a continuous chain of
> start and end points, a MultiLineString would be closed. Am I wrong
> somehow?
> 
> Thanks and regards,
> 
> Birgit.
> 
> 
> select st_isclosed(st_geomfromtext(
> 'MULTILINESTRING(
> (3584442.63274253 5842172.41579578,
>   3584358.9809     5842152.7361,
>   3584355.23337321 5842153.70245931),
> (3584355.23337321 5842153.70245931,
>   3584355.23330909 5842153.70247585,
>   3584355.23339452 5842153.70245382,
>   3584355.23337321 5842153.70245931),
> (3584355.23337321 5842153.70245931,
>   3584348.03488658 5842155.55873215,
>   3584345.68905341 5842155.07665686,
>   3584343.82931858 5842154.69447615,
>   3584340.46724669 5842152.9072508,
>   3584338.14023057 5842151.67024508,
>   3584328.33210257 5842146.45639614,
>   3584009.05607027 5842072.59988407,
>   3583887.98803815 5842042.75796404,
>   3583790.05011806 5842106.6478841,
>   3583790.05012    5842106.64788453,
>   3583878.43617231 5842126.47539268,
>   3584324.73120656 5842226.59207621,
>   3584329.67415529 5842229.44269127,
>   3584334.41005457 5842232.17390022,
>   3584368.1119426  5842240.76423623,
>   3584463.63629469 5842262.81966025,
>   3584488.97911407 5842268.84731974),
> (3584488.97911407 5842268.84731974,
>   3584488.97978147 5842268.84747848,
>   3584488.97978146 5842268.84747848,
>   3584488.97911407 5842268.84731974),
> (3584488.97911407 5842268.84731974,
>   3584488.97890809 5842268.84727075,
>   3584464.1099     5842262.3082,
>   3584464.10990818 5842262.30817579,
>   3584466.07027273 5842256.50678355,
>   3584472.08934014 5842238.694295,
>   3584472.08940751 5842238.69409565,
>   3584489.545      5842187.037,
>   3584489.5450305  5842187.03700481,
>   3584489.54503071 5842187.03700417,
>   3584526.86014482 5842192.92533864,
>   3584514.30279074 5842190.12385218,
>   3584495.65165472 5842186.30586817,
>   3584480.67207071 5842180.87201217,
>   3584458.64642469 5842176.18313362,
>   3584458.64634269 5842176.18311617,
>   3584442.63469631 5842172.41625542,
>   3584442.63274253 5842172.41579578))',31467));
> 
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