[postgis-users] Which length function should be used for linestrings

[Raghavan Krishnasamylakshmanaperumal]

Hi All,

I am trying to make use of linestring's length for one of my route
detection experiment.

My linestring data is in this format
"the_geom geometry(LineString,4326)"

I tried using ST_Length(the_geom), ST_Length(the_geom,true) and the results
are as follows,

*the_geom geometry(LineString,4326)*
"0102000020E6100000030000008204C58F31C551C070AC8BDB682C4540DA1B7C6132C551C0BF7D1D38672C45403333333333C551C00D4FAF94652C4540"
>


>
> *ST_Length(the_geom)*0.000141421356226931



> *ST_Length(the_geom,true) *i.e spheroid=true
> 13.8305487635736



What is the metric used for these st_length values? Also if I want to use
length as my edge cost in a graph formed out of these linestrings which
length function I should use?

-- 
Thanks,
Raghavan
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