var raster = new ol.layer.Tile({
  source: new ol.source.OSM()
});

var map = new ol.Map({
  layers: [raster],
  target: 'map',
  view: new ol.View({
    resolutions : customRes,
    center: [-11000000, 4600000],
    resolution    : 156543.0339
  })
});

/**
 * get the resolution out of scale
 * @param {number} scale as declared in the config eg 50000
 * @returns {window.webGisApp.main.resolutions}
 */
function getResolutionFromScale(scale){
var dpi = 25.4 / 0.28;
var mpu = ol.proj.METERS_PER_UNIT['m'];
var res = scale / (mpu * 39.37 * dpi);
return res;
}
/**
 * get the resolution out of scale
 * @param {number} res the resolution
 * @returns {webGisApp.main.resolutions}
 */
function getScaleFromResolution(res){
var dpi = 25.4 / 0.28;
var mpu = ol.proj.METERS_PER_UNIT['m'];
var scale = res * mpu * 39.37 * dpi;
return scale;
}