On 4/21/2014 11:25 AM, Raghavan Krishnasamylakshmanaperumal wrote:
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?

ST_Length() returns the distance is the object units. In 4326 this would be degrees

ST_Length on the spheriod is probably in meters.

-Steve

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