title: Proj4Leaflet orign on custom projection
body: <p>I've set up a Leaflet map using the fabulous <a href="http://kartena.github.io/Proj4Leaflet/api/" rel="nofollow">Proj4Leaflet</a> plugin. Within my map I'm using a custom reference system (<em>EPSG:28533</em>). The map tiles (<a href="http://sg.geodatenzentrum.de/wmts_webatlasde/tile/1.0.0/WMTSCapabilities.xml" rel="nofollow">WMTSCapabilities</a>) are fetched and rendered. But I have encountered that the tiles are transformed to the wrong location. The offset is approximately <strong>+9° lat</strong> and <strong>+7° lng</strong>. I expect, that I've set the wrong <code>origin</code> within the definition of the reference system (<a href="https://jsfiddle.net/Ld01h4zy/1/" rel="nofollow">fiddle</a>). </p>
  
  <pre><code>var rs25832 = new L.Proj.CRS(
      'EPSG:25832',
      '+proj=utm +zone=32 +ellps=GRS80 +units=m +no_defs', {
          origin: [
              // I suppose the error is here!
              265948.8191,
              7288831.7014
          ],
          resolutions: [
              // TileMatrixScaleDenominator * OGC_PixelWidth
              17471320.7509   * 0.00028,
              8735660.37545   * 0.00028,
              4367830.18772   * 0.00028,
              2183915.09386   * 0.00028,
              1091957.54693   * 0.00028,
              545978.773466   * 0.00028,
              272989.386733   * 0.00028,
              136494.693366   * 0.00028,
              68247.3466832   * 0.00028,
              34123.6733416   * 0.00028,
              17061.8366708   * 0.00028,
              8530.9183354    * 0.00028,
              4265.4591677    * 0.00028,
              2132.72958385   * 0.00028
          ]
      }
  );
  
  var url = 'http://sg.geodatenzentrum.de/wmts_webatlasde/tile/1.0.0/webatlasde/default/DE_EPSG_25832_ADV/{z}/{y}/{x}.png';      
  var layer = L.tileLayer(url, {
          maxZoom: rs25832.options.resolutions.length,
          continuousWorld: true
      }
  );
  
  var map = L.map('map', {
      crs: rs25832,
      center: [ 50.5881112, 7.2676084 ],
      zoom: 0,
      maxZoom: rs25832.options.resolutions.length,
      layers: [ layer ]
  });
  
  map.on('click', function(e) {
      alert('lat: ' + e.latlng.lat + ' lng: ' + e.latlng.lng)
  });
  </code></pre>
  
  <p>As far as I understood the <code>origin</code> setting it defines the upper left corner of the projected bounds of the refernce system. According to the <a href="http://www.spatialreference.org/ref/epsg/25832/" rel="nofollow">spatialreference.org</a> definition the bounds of this specific reference system are: </p>
  
  <pre><code>265948.8191, 6421521.2254, 677786.3629, 7288831.7014
  </code></pre>
  
  <p>Am I using the wrong approach to determine the CRS <code>origin</code>?</p>