diff --git a/externs/olcsx.js b/externs/olcsx.js
index a69717890..f04a329db 100644
--- a/externs/olcsx.js
+++ b/externs/olcsx.js
@@ -83,3 +83,13 @@ olcsx.core.OlFeatureToCesiumContext;
  * @api
  */
 olcsx.core.RotateAroundAxisOption;
+
+
+/**
+ * @typedef {{
+ *   url: string,
+ *   subdomains: string
+ * }}
+ * @api
+ */
+olcsx.core.CesiumUrlDefinition;
diff --git a/src/core.js b/src/core.js
index 9356e1d9b..1286538af 100644
--- a/src/core.js
+++ b/src/core.js
@@ -515,3 +515,29 @@ olcs.core.convertColorToCesium = function(olColor) {
   }
   goog.asserts.fail('impossible');
 };
+
+
+/**
+ * Convert an OpenLayers url to Cesium.
+ * @param {string} url
+ * @return {!olcsx.core.CesiumUrlDefinition}
+ * @api
+ */
+olcs.core.convertUrlToCesium = function(url) {
+  var subdomains = '';
+  var re = /\{(\d|[a-z])-(\d|[a-z])\}/;
+  var match = re.exec(url);
+  if (match) {
+    url = url.replace(re, '{s}');
+    var startCharCode = match[1].charCodeAt(0);
+    var stopCharCode = match[2].charCodeAt(0);
+    var charCode;
+    for (charCode = startCharCode; charCode <= stopCharCode; ++charCode) {
+      subdomains += String.fromCharCode(charCode);
+    }
+  }
+  return {
+    url: url,
+    subdomains: subdomains
+  };
+};