title: Conversion lambert to WGS84 (Geocoding + Oracle Locator)
body: <p>I'm currently tying to geocode addresses in Austria. From a given postal code and street etc. I want to automatically find latitude and longitude in WGS84 format. My first approach was to use a webservice like OpenStreetMaps Nominatim. Actually this gives decent results.</p>
  
  <p>Still it is <em>mandatory</em> to use a disk with addresses (PAC) and their respective geolocation as a ground truth. Only if I'm not able to match the address within this data I can use the web service approach as a backup solution.</p>
  
  <p>So much for context, now the problem:
  On this disk the gelocation is given as X_LAMBERT and Y_LAMBERT and I can't quite figure out how to convert into latitude+longitude.</p>
  
  <p>The diks's data is loaded into an Oracle 11g database with Locator and I'm doing the following:</p>
  
  <p>Step 1:
  Creation of spatial geometry object: <code>MDSYS.SDO_GEOMETRY(2003,31287,NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1,1003,1), MDSYS.SDO_ORDINATE_ARRAY(X_LAMBERT,Y_LAMBERT))</code></p>
  
  <p>Step 2: Projection from WGS84 to LatLng:
  <code>SDO_CS.TRANSFORM( GEOMETRY, 4326)</code> in my Java client I obtain latitude, longitude from the geometry via <code>oracle.spatial.geometry.JGeometry</code>. </p>
  
  <p>Note:
  I suspect 31287 to be SRID of the lambert format, I tried 8307 and 3416, but latter give even worse results.Step 2 works fine with other geometry objects, where I know the correct SRID for sure... so I guess the error is somewhere in Step 1.</p>
  
  <p>Do I have to set something in <code>USER_SDO_GEOM_METADATA</code> ? Wrong usage of <code>SDO_GEOMETRY</code> constructor ? Am I still mixing up datum and projection? Maybe you can enlighten me there aswell...</p>
  
  <p>The result of my action and example for input are:</p>
  
  <p><code>Input: X_LAMBERT 602823, Y_LAMBERT 464397
  Resulting Output: WGS84 (48.0469757028535, 16.0542604612583)
  Expected Output: WGS84 (48.546363, 16.085735)</code></p>
  
  <p>Its like almost correct, but still some 100 kilometers off ;-)</p>