[postgis-users] errors while using st_dwithin

[Paul Ramsey]

Are you working in the high polar regions? If not, your coordinates
are transposed. Put the 70s first. (lon, lat)

P.

On Thu, Dec 6, 2012 at 12:09 PM, tasneem dewaswala
<tasneem.europe at gmail.com> wrote:
> Hello,
>
> I tried with geography query for test purpose
>
> SELECT ST_Distance(
>   ST_GeographyFromText('POINT(19.246 72.969)'),
>   ST_GeographyFromText('POINT(19.164 72.926)')
>   );
>
> and it gives me the value 5498.79189851193
>
> while according to google maps distance is 10 km.
> I don't know how to get the approximate answer as in google maps.
> Please suggest whats wrong.
>
>
> On Thu, Dec 6, 2012 at 11:13 PM, Paul Ramsey <pramsey at opengeo.org> wrote:
>>
>> Ah. Geography is version 1.5+
>> You can put st_distance_spheroid in place of st_distance for a metric
>> answer.
>> p
>>
>> On Thu, Dec 6, 2012 at 9:40 AM, tasneem dewaswala
>> <tasneem.europe at gmail.com> wrote:
>> > Thank you for the suggestion
>> >
>> > i tried to use ST_GeographyFromText and ST_GeogFromText
>> > but it gives an error as the function does not exist.
>> >
>> > is this because of version problem.
>> >
>> > My postgre version is
>> > "PostgreSQL 8.4.14, compiled by Visual C++ build 1400, 32-bit"
>> >
>> > and postgis version is
>> > "POSTGIS="1.4.2" GEOS="3.2.0-CAPI-1.6.0" PROJ="Rel. 4.6.1, 21 August
>> > 2008"
>> > USE_STATS"
>> >
>> >
>> > On Thu, Dec 6, 2012 at 10:29 PM, Paul Ramsey <pramsey at opengeo.org>
>> > wrote:
>> >>
>> >> If you want to use angular units (lon/lat) but get back metric
>> >> results, use the geography type, not the geometry type.
>> >> ST_GeogFromText
>> >>
>> >> On Thu, Dec 6, 2012 at 8:56 AM, tasneem dewaswala
>> >> <tasneem.europe at gmail.com> wrote:
>> >> > When i locate this two co-ordinates on google map.
>> >> >  one lat/lon (19.235308 72.977955) is in India while
>> >> > another (56.6647756667,12.877464) is in Sweden,
>> >> > so how can the distance between both of them be 70 meters ?
>> >> >
>> >> >
>> >> > On Thu, Dec 6, 2012 at 9:30 PM, Duncan Golicher <dgolicher at gmail.com>
>> >> > wrote:
>> >> >>
>> >> >> The points look about 70m apart to me.
>> >> >>
>> >> >> Duncan
>> >> >>
>> >> >>
>> >> >>
>> >> >> On Thu, Dec 6, 2012 at 8:47 AM, tasneem dewaswala
>> >> >> <tasneem.europe at gmail.com> wrote:
>> >> >> > Hello,
>> >> >> >
>> >> >> > i want to know whether two location's are within 100 meters range
>> >> >> > of
>> >> >> > each
>> >> >> > other or not.
>> >> >> > i tried using ST_DWITHIN, but its not giving me appropriate
>> >> >> > answers.
>> >> >> >
>> >> >> > my query is "
>> >> >> >
>> >> >> > select st_dwithin(ST_GeomFromText('POINT(19.235308
>> >> >> > 72.977955)',2163),ST_GeomFromText('POINT(56.6647756667
>> >> >> > 12.877464)',2163),100) as "result";
>> >> >> >
>> >> >> > the result that i get is "t" i.e true, which is logically not
>> >> >> > correct,
>> >> >> > the
>> >> >> > answer i should get is false, since two locations are far beyond
>> >> >> > 100
>> >> >> > meters
>> >> >> > range.
>> >> >> >
>> >> >> > Please help me forming an exact query for this.
>> >> >> >
>> >> >> > Regards
>> >> >> > Tasha
>> >> >> >
>> >> >> >
>> >> >> > _______________________________________________
>> >> >> > postgis-users mailing list
>> >> >> > postgis-users at lists.osgeo.org
>> >> >> > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>> >> >> >
>> >> >>
>> >> >>
>> >> >>
>> >> >> --
>> >> >> Dr Duncan Golicher
>> >> >> Investigador Titular,
>> >> >> El Colegio de la Frontera Sur, Chiapas,Mexico
>> >> >> Mexico tel +52 1 967 137 94 20
>> >> >> Skype name duncangolicher
>> >> >>
>> >> >> Publications: http://www.mendeley.com/profiles/duncan-golicher
>> >> >>
>> >> >> Senior lecturer, Bournemouth University, UK
>> >> >> Centre for Conservation Ecology & Environmental Change
>> >> >> School of Applied Sciences
>> >> >> Christchurch House rm C218a
>> >> >> Bournemouth University
>> >> >> Fern Barrow
>> >> >> Poole (Dorset) BH12 5BB UK
>> >> >> Tel. +44 (0)1202 961682
>> >> >>
>> >> >> For list of publications see Researcher ID:
>> >> >> http://www.researcherid.com/rid/B-4240-2009
>> >> >>
>> >> >> dgolicher at bournemouth.ac.uk
>> >> >> dgoliche at ecosur.mx
>> >> >>
>> >> >> Researcher ID:
>> >> >> http://www.researcherid.com/rid/B-4240-2009
>> >> >> _______________________________________________
>> >> >> postgis-users mailing list
>> >> >> postgis-users at lists.osgeo.org
>> >> >> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>> >> >
>> >> >
>> >> >
>> >> > _______________________________________________
>> >> > postgis-users mailing list
>> >> > postgis-users at lists.osgeo.org
>> >> > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>> >> >
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>> >
>> >
>> >
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>> >
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