title: How to create a circle in meters in postgis?
body: <p>I would like to ask how to create a circle with <code>radius=4km</code>. I have tried the <code>ST_Buffer</code> function but it creates a larger circle. (I see the created circle by inserting its polygon into an new kml file.)</p>
  
  <p>This is what i am trying.</p>
  
  <pre><code>INSERT INTO camera(geom_circle) VALUES(geometry(ST_Buffer(georgaphy(ST_GeomFromText('POINT(21.304116745663165 38.68607570952619)')), 4000)))
  </code></pre>
  
  <p>The center of the circle is a lon lat point but I don't know its <code>SRID</code> because I have imported it from a kml file.
  Do I need the <code>SRID</code> in order to transform the geometries etc?</p>