# [postgis-users] ST_DWithin with radius 0.000001

nguyen liem liemnguyendl at gmail.com
Tue May 25 07:33:06 PDT 2010

```Hi Charles

Thanks for your answer, i can understand a little, i will try to research
more.
One more time, i would like to say thank you with you and Nicklas.

Cheers

On Tue, May 25, 2010 at 6:47 PM, Charles Galpin <cgalpin at lhsw.com> wrote:

>
> On May 25, 2010, at 5:43 AM, nguyen liem wrote:
>
> > One more question, if i would like to use ST_DWithin in projection WGS84
> and the radius is in 1 meter, how to do that?
>
> As someone else said it depends on the latitude you are dealing with, but
> you take the circumference of the earth at your location and divide by 360
> to get one degree. So at the equator one degree is roughly 69 miles or
> 111km.  So 0.00001 is 1m at the equator (but is .8m in NJ for example).
>
> hth,
> charles
>
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>

--
Liem Nguyen
Developer
Axon Active Corp.
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