diff --git a/examples/bind-input.js b/examples/bind-input.js
index 6668f1bed7..52deeb0c07 100644
--- a/examples/bind-input.js
+++ b/examples/bind-input.js
@@ -57,9 +57,10 @@ brightness.bindTo('value', layer, 'brightness')
 
 
 var rotation = new ol.dom.Input(document.getElementById('rotation'));
-rotation.bindTo('value', map.getView(), 'rotation')
+rotation.bindTo('value', /** @type {ol.View2D} */ (map.getView()), 'rotation')
     .transform(parseFloat, String);
 
 var resolution = new ol.dom.Input(document.getElementById('resolution'));
-resolution.bindTo('value', map.getView(), 'resolution')
+resolution.bindTo('value',
+    /** @type {ol.View2D} */ (map.getView()), 'resolution')
     .transform(parseFloat, String);
diff --git a/examples/device-orientation.js b/examples/device-orientation.js
index 318dc6468d..caf1f8cf98 100644
--- a/examples/device-orientation.js
+++ b/examples/device-orientation.js
@@ -6,6 +6,10 @@ goog.require('ol.dom.Input');
 goog.require('ol.layer.Tile');
 goog.require('ol.source.OSM');
 
+var view = new ol.View2D({
+  center: [0, 0],
+  zoom: 2
+});
 var map = new ol.Map({
   layers: [
     new ol.layer.Tile({
@@ -14,12 +18,8 @@ var map = new ol.Map({
   ],
   renderers: ol.RendererHints.createFromQueryData(),
   target: 'map',
-  view: new ol.View2D({
-    center: [0, 0],
-    zoom: 2
-  })
+  view: view
 });
-var view = map.getView();
 
 var deviceOrientation = new ol.DeviceOrientation();
 var track = new ol.dom.Input(document.getElementById('track'));
diff --git a/examples/geolocation.js b/examples/geolocation.js
index fc0d2ac62e..850e1b226f 100644
--- a/examples/geolocation.js
+++ b/examples/geolocation.js
@@ -24,7 +24,7 @@ var map = new ol.Map({
 });
 
 var geolocation = new ol.Geolocation();
-geolocation.bindTo('projection', map.getView());
+geolocation.bindTo('projection', /** @type {ol.View2D} */ (map.getView()));
 
 var track = new ol.dom.Input(document.getElementById('track'));
 track.bindTo('checked', geolocation, 'tracking');
diff --git a/examples/vector-layer-sld.js b/examples/vector-layer-sld.js
index 585cc66c09..89f2ba710d 100644
--- a/examples/vector-layer-sld.js
+++ b/examples/vector-layer-sld.js
@@ -36,8 +36,10 @@ xhr.onload = function() {
         zoom: 1
       })
     });
-    var units = map.getView().getProjection().getUnits();
-    var sld = new ol.parser.ogc.SLD().read(xhr.responseText, units);
+    var units = map.getView().getView2D().getProjection().getUnits();
+    var sld = new ol.parser.ogc.SLD().read(xhr.responseText, {
+      units: units
+    });
     var style = sld.namedLayers['countries'].userStyles[0];
     var vector = new ol.layer.Vector({
       source: new ol.source.Vector({
diff --git a/src/ol/attribution.js b/src/ol/attribution.js
index 560e52facf..3c95c8b83d 100644
--- a/src/ol/attribution.js
+++ b/src/ol/attribution.js
@@ -21,6 +21,7 @@ goog.require('ol.TileRange');
  *
  * @constructor
  * @param {olx.AttributionOptions} options Attribution options.
+ * @struct
  * @todo stability experimental
  */
 ol.Attribution = function(options) {
diff --git a/src/ol/canvas/canvas.js b/src/ol/canvas/canvas.js
index 266718953d..99bcd99217 100644
--- a/src/ol/canvas/canvas.js
+++ b/src/ol/canvas/canvas.js
@@ -9,15 +9,19 @@ goog.require('goog.dom.TagName');
  * @const
  * @type {boolean}
  */
-ol.canvas.SUPPORTED = (function() {
-  if (!('HTMLCanvasElement' in goog.global)) {
-    return false;
-  }
-  try {
-    var canvas = /** @type {HTMLCanvasElement} */
-        (goog.dom.createElement(goog.dom.TagName.CANVAS));
-    return !goog.isNull(canvas.getContext('2d'));
-  } catch (e) {
-    return false;
-  }
-})();
+ol.canvas.SUPPORTED = (
+    /**
+     * @return {boolean} Canvas supported.
+     */
+    function() {
+      if (!('HTMLCanvasElement' in goog.global)) {
+        return false;
+      }
+      try {
+        var canvas = /** @type {HTMLCanvasElement} */
+            (goog.dom.createElement(goog.dom.TagName.CANVAS));
+        return !goog.isNull(canvas.getContext('2d'));
+      } catch (e) {
+        return false;
+      }
+    })();
diff --git a/src/ol/control/zoomcontrol.js b/src/ol/control/zoomcontrol.js
index f31b6aaa66..5c8fe4ca4a 100644
--- a/src/ol/control/zoomcontrol.js
+++ b/src/ol/control/zoomcontrol.js
@@ -2,10 +2,12 @@
 
 goog.provide('ol.control.Zoom');
 
+goog.require('goog.asserts');
 goog.require('goog.dom');
 goog.require('goog.dom.TagName');
 goog.require('goog.events');
 goog.require('goog.events.EventType');
+goog.require('ol.View2D');
 goog.require('ol.animation');
 goog.require('ol.control.Control');
 goog.require('ol.css');
@@ -77,8 +79,11 @@ ol.control.Zoom.prototype.zoomByDelta_ = function(delta, browserEvent) {
   browserEvent.preventDefault();
   var map = this.getMap();
   // FIXME works for View2D only
-  var view = map.getView().getView2D();
-  var currentResolution = view.getResolution();
+  var view = map.getView();
+  goog.asserts.assert(goog.isDef(view));
+  var view2D = view.getView2D();
+  goog.asserts.assertInstanceof(view2D, ol.View2D);
+  var currentResolution = view2D.getResolution();
   if (goog.isDef(currentResolution)) {
     if (this.duration_ > 0) {
       map.beforeRender(ol.animation.zoom({
@@ -87,7 +92,7 @@ ol.control.Zoom.prototype.zoomByDelta_ = function(delta, browserEvent) {
         easing: ol.easing.easeOut
       }));
     }
-    var newResolution = view.constrainResolution(currentResolution, delta);
-    view.setResolution(newResolution);
+    var newResolution = view2D.constrainResolution(currentResolution, delta);
+    view2D.setResolution(newResolution);
   }
 };
diff --git a/src/ol/dom/dom.js b/src/ol/dom/dom.js
index 3cf809611e..44d86b8b43 100644
--- a/src/ol/dom/dom.js
+++ b/src/ol/dom/dom.js
@@ -31,7 +31,7 @@ ol.dom.setTransform = function(element, value) {
 
 /**
  * @param {Element} element Element.
- * @param {goog.vec.Mat4.AnyType} transform Matrix.
+ * @param {goog.vec.Mat4.Number} transform Matrix.
  * @param {number=} opt_precision Precision.
  */
 ol.dom.transformElement2D = function(element, transform, opt_precision) {
diff --git a/src/ol/interaction/dragpaninteraction.js b/src/ol/interaction/dragpaninteraction.js
index d98a801639..2b2b3231d4 100644
--- a/src/ol/interaction/dragpaninteraction.js
+++ b/src/ol/interaction/dragpaninteraction.js
@@ -84,11 +84,13 @@ ol.interaction.DragPan.prototype.handleDragEnd = function(mapBrowserEvent) {
   // FIXME works for View2D only
 
   var map = mapBrowserEvent.map;
-  var view = map.getView().getView2D();
+  var view = map.getView();
   view.setHint(ol.ViewHint.INTERACTING, -1);
 
   if (this.kinetic_ && this.kinetic_.end()) {
-    var view2DState = view.getView2DState();
+    var view2D = view.getView2D();
+    goog.asserts.assertInstanceof(view2D, ol.View2D);
+    var view2DState = view2D.getView2DState();
     var distance = this.kinetic_.getDistance();
     var angle = this.kinetic_.getAngle();
     this.kineticPreRenderFn_ = this.kinetic_.pan(view2DState.center);
@@ -99,8 +101,8 @@ ol.interaction.DragPan.prototype.handleDragEnd = function(mapBrowserEvent) {
       centerpx[0] - distance * Math.cos(angle),
       centerpx[1] - distance * Math.sin(angle)
     ]);
-    dest = view.constrainCenter(dest);
-    view.setCenter(dest);
+    dest = view2D.constrainCenter(dest);
+    view2D.setCenter(dest);
   }
   map.requestRenderFrame();
 };
diff --git a/src/ol/interaction/dragrotateandzoominteraction.js b/src/ol/interaction/dragrotateandzoominteraction.js
index b2588a2af3..fdef314122 100644
--- a/src/ol/interaction/dragrotateandzoominteraction.js
+++ b/src/ol/interaction/dragrotateandzoominteraction.js
@@ -105,13 +105,14 @@ ol.interaction.DragRotateAndZoom.prototype.handleDragEnd =
     function(mapBrowserEvent) {
   var map = mapBrowserEvent.map;
   // FIXME works for View2D only
-  var view = map.getView().getView2D();
+  var view = map.getView();
   view.setHint(ol.ViewHint.INTERACTING, -1);
-  var view2DState = view.getView2DState();
+  var view2D = view.getView2D();
+  var view2DState = view2D.getView2DState();
   var direction = this.lastScaleDelta_ - 1;
   map.withFrozenRendering(function() {
-    ol.interaction.Interaction.rotate(map, view, view2DState.rotation);
-    ol.interaction.Interaction.zoom(map, view, view2DState.resolution,
+    ol.interaction.Interaction.rotate(map, view2D, view2DState.rotation);
+    ol.interaction.Interaction.zoom(map, view2D, view2DState.resolution,
         undefined, ol.interaction.DRAGROTATEANDZOOM_ANIMATION_DURATION,
         direction);
   });
diff --git a/src/ol/interaction/dragrotateinteraction.js b/src/ol/interaction/dragrotateinteraction.js
index 06a85e3eb9..eceed9dfc6 100644
--- a/src/ol/interaction/dragrotateinteraction.js
+++ b/src/ol/interaction/dragrotateinteraction.js
@@ -74,11 +74,12 @@ ol.interaction.DragRotate.prototype.handleDrag = function(mapBrowserEvent) {
 ol.interaction.DragRotate.prototype.handleDragEnd = function(mapBrowserEvent) {
   var map = mapBrowserEvent.map;
   // FIXME works for View2D only
-  var view = map.getView().getView2D();
+  var view = map.getView();
   view.setHint(ol.ViewHint.INTERACTING, -1);
-  var view2DState = view.getView2DState();
-  ol.interaction.Interaction.rotate(map, view, view2DState.rotation, undefined,
-      ol.interaction.DRAGROTATE_ANIMATION_DURATION);
+  var view2D = view.getView2D();
+  var view2DState = view2D.getView2DState();
+  ol.interaction.Interaction.rotate(map, view2D, view2DState.rotation,
+      undefined, ol.interaction.DRAGROTATE_ANIMATION_DURATION);
 };
 
 
diff --git a/src/ol/interaction/interaction.js b/src/ol/interaction/interaction.js
index b4b9c6f86d..2fdbf57cdf 100644
--- a/src/ol/interaction/interaction.js
+++ b/src/ol/interaction/interaction.js
@@ -2,8 +2,10 @@
 
 goog.provide('ol.interaction.Interaction');
 
+goog.require('goog.asserts');
 goog.require('goog.events.EventTarget');
 goog.require('ol.MapBrowserEvent');
+goog.require('ol.View2D');
 goog.require('ol.animation');
 goog.require('ol.easing');
 
@@ -58,12 +60,13 @@ ol.interaction.Interaction.prototype.setMap = function(map) {
 
 /**
  * @param {ol.Map} map Map.
- * @param {ol.View2D} view View.
+ * @param {ol.IView2D} view View.
  * @param {ol.Coordinate} delta Delta.
  * @param {number=} opt_duration Duration.
  */
 ol.interaction.Interaction.pan = function(
     map, view, delta, opt_duration) {
+  goog.asserts.assertInstanceof(view, ol.View2D);
   var currentCenter = view.getCenter();
   if (goog.isDef(currentCenter)) {
     if (goog.isDef(opt_duration) && opt_duration > 0) {
@@ -82,13 +85,14 @@ ol.interaction.Interaction.pan = function(
 
 /**
  * @param {ol.Map} map Map.
- * @param {ol.View2D} view View.
+ * @param {ol.IView2D} view View.
  * @param {number|undefined} rotation Rotation.
  * @param {ol.Coordinate=} opt_anchor Anchor coordinate.
  * @param {number=} opt_duration Duration.
  */
 ol.interaction.Interaction.rotate =
     function(map, view, rotation, opt_anchor, opt_duration) {
+  goog.asserts.assertInstanceof(view, ol.View2D);
   rotation = view.constrainRotation(rotation, 0);
   ol.interaction.Interaction.rotateWithoutConstraints(
       map, view, rotation, opt_anchor, opt_duration);
@@ -97,13 +101,14 @@ ol.interaction.Interaction.rotate =
 
 /**
  * @param {ol.Map} map Map.
- * @param {ol.View2D} view View.
+ * @param {ol.IView2D} view View.
  * @param {number|undefined} rotation Rotation.
  * @param {ol.Coordinate=} opt_anchor Anchor coordinate.
  * @param {number=} opt_duration Duration.
  */
 ol.interaction.Interaction.rotateWithoutConstraints =
     function(map, view, rotation, opt_anchor, opt_duration) {
+  goog.asserts.assertInstanceof(view, ol.View2D);
   if (goog.isDefAndNotNull(rotation)) {
     var currentRotation = view.getRotation();
     var currentCenter = view.getCenter();
@@ -125,6 +130,7 @@ ol.interaction.Interaction.rotateWithoutConstraints =
     if (goog.isDefAndNotNull(opt_anchor)) {
       var center = view.calculateCenterRotate(rotation, opt_anchor);
       map.withFrozenRendering(function() {
+        goog.asserts.assertInstanceof(view, ol.View2D);
         view.setCenter(center);
         view.setRotation(rotation);
       });
@@ -137,7 +143,7 @@ ol.interaction.Interaction.rotateWithoutConstraints =
 
 /**
  * @param {ol.Map} map Map.
- * @param {ol.View2D} view View.
+ * @param {ol.IView2D} view View.
  * @param {number|undefined} resolution Resolution to go to.
  * @param {ol.Coordinate=} opt_anchor Anchor coordinate.
  * @param {number=} opt_duration Duration.
@@ -152,6 +158,7 @@ ol.interaction.Interaction.rotateWithoutConstraints =
  */
 ol.interaction.Interaction.zoom =
     function(map, view, resolution, opt_anchor, opt_duration, opt_direction) {
+  goog.asserts.assertInstanceof(view, ol.View2D);
   resolution = view.constrainResolution(resolution, 0, opt_direction);
   ol.interaction.Interaction.zoomWithoutConstraints(
       map, view, resolution, opt_anchor, opt_duration);
@@ -160,13 +167,14 @@ ol.interaction.Interaction.zoom =
 
 /**
  * @param {ol.Map} map Map.
- * @param {ol.View2D} view View.
+ * @param {ol.IView2D} view View.
  * @param {number} delta Delta from previous zoom level.
  * @param {ol.Coordinate=} opt_anchor Anchor coordinate.
  * @param {number=} opt_duration Duration.
  */
 ol.interaction.Interaction.zoomByDelta =
     function(map, view, delta, opt_anchor, opt_duration) {
+  goog.asserts.assertInstanceof(view, ol.View2D);
   var currentResolution = view.getResolution();
   var resolution = view.constrainResolution(currentResolution, delta, 0);
   ol.interaction.Interaction.zoomWithoutConstraints(
@@ -176,13 +184,14 @@ ol.interaction.Interaction.zoomByDelta =
 
 /**
  * @param {ol.Map} map Map.
- * @param {ol.View2D} view View.
+ * @param {ol.IView2D} view View.
  * @param {number|undefined} resolution Resolution to go to.
  * @param {ol.Coordinate=} opt_anchor Anchor coordinate.
  * @param {number=} opt_duration Duration.
  */
 ol.interaction.Interaction.zoomWithoutConstraints =
     function(map, view, resolution, opt_anchor, opt_duration) {
+  goog.asserts.assertInstanceof(view, ol.View2D);
   if (goog.isDefAndNotNull(resolution)) {
     var currentResolution = view.getResolution();
     var currentCenter = view.getCenter();
@@ -204,6 +213,7 @@ ol.interaction.Interaction.zoomWithoutConstraints =
     if (goog.isDefAndNotNull(opt_anchor)) {
       var center = view.calculateCenterZoom(resolution, opt_anchor);
       map.withFrozenRendering(function() {
+        goog.asserts.assertInstanceof(view, ol.View2D);
         view.setCenter(center);
         view.setResolution(resolution);
       });
diff --git a/src/ol/interaction/touchpaninteraction.js b/src/ol/interaction/touchpaninteraction.js
index 3f2efb7cb6..026fd6c881 100644
--- a/src/ol/interaction/touchpaninteraction.js
+++ b/src/ol/interaction/touchpaninteraction.js
@@ -5,6 +5,7 @@ goog.require('goog.asserts');
 goog.require('ol.Kinetic');
 goog.require('ol.Pixel');
 goog.require('ol.PreRenderFunction');
+goog.require('ol.View2D');
 goog.require('ol.coordinate');
 goog.require('ol.interaction.Touch');
 
@@ -64,15 +65,16 @@ ol.interaction.TouchPan.prototype.handleTouchMove = function(mapBrowserEvent) {
     var deltaX = this.lastCentroid[0] - centroid[0];
     var deltaY = centroid[1] - this.lastCentroid[1];
     var map = mapBrowserEvent.map;
-    var view = map.getView().getView2D();
-    var view2DState = view.getView2DState();
+    var view2D = map.getView().getView2D();
+    goog.asserts.assertInstanceof(view2D, ol.View2D);
+    var view2DState = view2D.getView2DState();
     var center = [deltaX, deltaY];
     ol.coordinate.scale(center, view2DState.resolution);
     ol.coordinate.rotate(center, view2DState.rotation);
     ol.coordinate.add(center, view2DState.center);
-    center = view.constrainCenter(center);
+    center = view2D.constrainCenter(center);
     map.requestRenderFrame();
-    view.setCenter(center);
+    view2D.setCenter(center);
   }
   this.lastCentroid = centroid;
 };
@@ -84,12 +86,14 @@ ol.interaction.TouchPan.prototype.handleTouchMove = function(mapBrowserEvent) {
 ol.interaction.TouchPan.prototype.handleTouchEnd =
     function(mapBrowserEvent) {
   var map = mapBrowserEvent.map;
-  var view = map.getView();
+  var view2D = map.getView().getView2D();
+  goog.asserts.assertInstanceof(view2D, ol.View2D);
   if (this.targetTouches.length === 0) {
     if (!this.noKinetic_ && this.kinetic_ && this.kinetic_.end()) {
       var distance = this.kinetic_.getDistance();
       var angle = this.kinetic_.getAngle();
-      var center = view.getCenter();
+      var center = view2D.getCenter();
+      goog.asserts.assert(goog.isDef(center));
       this.kineticPreRenderFn_ = this.kinetic_.pan(center);
       map.beforeRender(this.kineticPreRenderFn_);
       var centerpx = map.getPixelFromCoordinate(center);
@@ -97,8 +101,8 @@ ol.interaction.TouchPan.prototype.handleTouchEnd =
         centerpx[0] - distance * Math.cos(angle),
         centerpx[1] - distance * Math.sin(angle)
       ]);
-      dest = view.constrainCenter(dest);
-      view.setCenter(dest);
+      dest = view2D.constrainCenter(dest);
+      view2D.setCenter(dest);
     }
     map.requestRenderFrame();
     return false;
@@ -116,12 +120,13 @@ ol.interaction.TouchPan.prototype.handleTouchStart =
     function(mapBrowserEvent) {
   if (this.targetTouches.length > 0) {
     var map = mapBrowserEvent.map;
-    var view = map.getView();
+    var view2D = map.getView().getView2D();
+    goog.asserts.assertInstanceof(view2D, ol.View2D);
     this.lastCentroid = null;
     map.requestRenderFrame();
     if (!goog.isNull(this.kineticPreRenderFn_) &&
         map.removePreRenderFunction(this.kineticPreRenderFn_)) {
-      view.setCenter(mapBrowserEvent.frameState.view2DState.center);
+      view2D.setCenter(mapBrowserEvent.frameState.view2DState.center);
       this.kineticPreRenderFn_ = null;
     }
     if (this.kinetic_) {
diff --git a/src/ol/iview.js b/src/ol/iview.js
index 5b7663bd1d..37d828d3e2 100644
--- a/src/ol/iview.js
+++ b/src/ol/iview.js
@@ -25,3 +25,10 @@ ol.IView.prototype.getView2D = function() {
  */
 ol.IView.prototype.getView3D = function() {
 };
+
+
+/**
+ * @return {boolean} Is defined.
+ */
+ol.IView.prototype.isDef = function() {
+};
diff --git a/src/ol/iview2d.js b/src/ol/iview2d.js
index cd3cb188f4..0969e6d696 100644
--- a/src/ol/iview2d.js
+++ b/src/ol/iview2d.js
@@ -59,3 +59,10 @@ ol.IView2D.prototype.getRotation = function() {
  */
 ol.IView2D.prototype.getView2DState = function() {
 };
+
+
+/**
+ * @return {boolean} Is defined.
+ */
+ol.IView2D.prototype.isDef = function() {
+};
diff --git a/src/ol/iview3d.js b/src/ol/iview3d.js
index c74f9acf6b..b54f7d7e42 100644
--- a/src/ol/iview3d.js
+++ b/src/ol/iview3d.js
@@ -8,3 +8,10 @@ goog.provide('ol.IView3D');
  */
 ol.IView3D = function() {
 };
+
+
+/**
+ * @return {boolean} Is defined.
+ */
+ol.IView3D.prototype.isDef = function() {
+};
diff --git a/src/ol/kinetic.js b/src/ol/kinetic.js
index 7bdbf1a3d4..56833aed1b 100644
--- a/src/ol/kinetic.js
+++ b/src/ol/kinetic.js
@@ -13,6 +13,7 @@ goog.require('ol.animation');
  * @param {number} minVelocity Minimum velocity (pixels/millisecond).
  * @param {number} delay Delay to consider to calculate the kinetic
  *     initial values (milliseconds).
+ * @struct
  * @todo stability experimental
  */
 ol.Kinetic = function(decay, minVelocity, delay) {
diff --git a/src/ol/layer/imagelayer.js b/src/ol/layer/imagelayer.js
index d75edf8ded..9f8d1bf4e3 100644
--- a/src/ol/layer/imagelayer.js
+++ b/src/ol/layer/imagelayer.js
@@ -1,7 +1,6 @@
 goog.provide('ol.layer.Image');
 
 goog.require('ol.layer.Layer');
-goog.require('ol.source.Image');
 
 
 
@@ -15,11 +14,3 @@ ol.layer.Image = function(options) {
   goog.base(this, options);
 };
 goog.inherits(ol.layer.Image, ol.layer.Layer);
-
-
-/**
- * @return {ol.source.Image} Single image source.
- */
-ol.layer.Image.prototype.getImageSource = function() {
-  return /** @type {ol.source.Image} */ (this.getSource());
-};
diff --git a/src/ol/layer/layerbase.js b/src/ol/layer/layerbase.js
index 389f3afef7..8ddeeb3c32 100644
--- a/src/ol/layer/layerbase.js
+++ b/src/ol/layer/layerbase.js
@@ -84,10 +84,11 @@ ol.layer.Base.prototype.dispatchChangeEvent = function() {
 
 
 /**
- * @return {number} Brightness.
+ * @return {number|undefined} Brightness.
  */
 ol.layer.Base.prototype.getBrightness = function() {
-  return /** @type {number} */ (this.get(ol.layer.LayerProperty.BRIGHTNESS));
+  return /** @type {number|undefined} */ (
+      this.get(ol.layer.LayerProperty.BRIGHTNESS));
 };
 goog.exportProperty(
     ol.layer.Base.prototype,
@@ -96,10 +97,11 @@ goog.exportProperty(
 
 
 /**
- * @return {number} Contrast.
+ * @return {number|undefined} Contrast.
  */
 ol.layer.Base.prototype.getContrast = function() {
-  return /** @type {number} */ (this.get(ol.layer.LayerProperty.CONTRAST));
+  return /** @type {number|undefined} */ (
+      this.get(ol.layer.LayerProperty.CONTRAST));
 };
 goog.exportProperty(
     ol.layer.Base.prototype,
@@ -108,10 +110,10 @@ goog.exportProperty(
 
 
 /**
- * @return {number} Hue.
+ * @return {number|undefined} Hue.
  */
 ol.layer.Base.prototype.getHue = function() {
-  return /** @type {number} */ (this.get(ol.layer.LayerProperty.HUE));
+  return /** @type {number|undefined} */ (this.get(ol.layer.LayerProperty.HUE));
 };
 goog.exportProperty(
     ol.layer.Base.prototype,
@@ -168,10 +170,10 @@ ol.layer.Base.prototype.getLayerStatesArray = goog.abstractMethod;
 
 
 /**
- * @return {number} MaxResolution.
+ * @return {number|undefined} MaxResolution.
  */
 ol.layer.Base.prototype.getMaxResolution = function() {
-  return /** @type {number} */ (
+  return /** @type {number|undefined} */ (
       this.get(ol.layer.LayerProperty.MAX_RESOLUTION));
 };
 goog.exportProperty(
@@ -181,10 +183,10 @@ goog.exportProperty(
 
 
 /**
- * @return {number} MinResolution.
+ * @return {number|undefined} MinResolution.
  */
 ol.layer.Base.prototype.getMinResolution = function() {
-  return /** @type {number} */ (
+  return /** @type {number|undefined} */ (
       this.get(ol.layer.LayerProperty.MIN_RESOLUTION));
 };
 goog.exportProperty(
@@ -194,10 +196,11 @@ goog.exportProperty(
 
 
 /**
- * @return {number} Opacity.
+ * @return {number|undefined} Opacity.
  */
 ol.layer.Base.prototype.getOpacity = function() {
-  return /** @type {number} */ (this.get(ol.layer.LayerProperty.OPACITY));
+  return /** @type {number|undefined} */ (
+      this.get(ol.layer.LayerProperty.OPACITY));
 };
 goog.exportProperty(
     ol.layer.Base.prototype,
@@ -206,10 +209,11 @@ goog.exportProperty(
 
 
 /**
- * @return {number} Saturation.
+ * @return {number|undefined} Saturation.
  */
 ol.layer.Base.prototype.getSaturation = function() {
-  return /** @type {number} */ (this.get(ol.layer.LayerProperty.SATURATION));
+  return /** @type {number|undefined} */ (
+      this.get(ol.layer.LayerProperty.SATURATION));
 };
 goog.exportProperty(
     ol.layer.Base.prototype,
@@ -224,10 +228,11 @@ ol.layer.Base.prototype.getSourceState = goog.abstractMethod;
 
 
 /**
- * @return {boolean} Visible.
+ * @return {boolean|undefined} Visible.
  */
 ol.layer.Base.prototype.getVisible = function() {
-  return /** @type {boolean} */ (this.get(ol.layer.LayerProperty.VISIBLE));
+  return /** @type {boolean|undefined} */ (
+      this.get(ol.layer.LayerProperty.VISIBLE));
 };
 goog.exportProperty(
     ol.layer.Base.prototype,
@@ -253,7 +258,7 @@ goog.exportProperty(
  * [2] https://github.com/WebKit/webkit/commit/8f4765e569
  * [3] https://www.w3.org/Bugs/Public/show_bug.cgi?id=15647
  *
- * @param {number} brightness Brightness.
+ * @param {number|undefined} brightness Brightness.
  */
 ol.layer.Base.prototype.setBrightness = function(brightness) {
   this.set(ol.layer.LayerProperty.BRIGHTNESS, brightness);
@@ -269,7 +274,7 @@ goog.exportProperty(
  * grey.  A value of 1 will leave the contrast unchanged.  Other values are
  * linear multipliers on the effect (and values over 1 are permitted).
  *
- * @param {number} contrast Contrast.
+ * @param {number|undefined} contrast Contrast.
  */
 ol.layer.Base.prototype.setContrast = function(contrast) {
   this.set(ol.layer.LayerProperty.CONTRAST, contrast);
@@ -283,7 +288,7 @@ goog.exportProperty(
 /**
  * Apply a hue-rotation to the layer.  A value of 0 will leave the hue
  * unchanged.  Other values are radians around the color circle.
- * @param {number} hue Hue.
+ * @param {number|undefined} hue Hue.
  */
 ol.layer.Base.prototype.setHue = function(hue) {
   this.set(ol.layer.LayerProperty.HUE, hue);
@@ -295,7 +300,7 @@ goog.exportProperty(
 
 
 /**
- * @param {number} maxResolution MaxResolution.
+ * @param {number|undefined} maxResolution MaxResolution.
  */
 ol.layer.Base.prototype.setMaxResolution = function(maxResolution) {
   this.set(ol.layer.LayerProperty.MAX_RESOLUTION, maxResolution);
@@ -307,7 +312,7 @@ goog.exportProperty(
 
 
 /**
- * @param {number} minResolution MinResolution.
+ * @param {number|undefined} minResolution MinResolution.
  */
 ol.layer.Base.prototype.setMinResolution = function(minResolution) {
   this.set(ol.layer.LayerProperty.MIN_RESOLUTION, minResolution);
@@ -319,7 +324,7 @@ goog.exportProperty(
 
 
 /**
- * @param {number} opacity Opacity.
+ * @param {number|undefined} opacity Opacity.
  */
 ol.layer.Base.prototype.setOpacity = function(opacity) {
   this.set(ol.layer.LayerProperty.OPACITY, opacity);
@@ -336,7 +341,7 @@ goog.exportProperty(
  * values are linear multipliers of the effect (and values over 1 are
  * permitted).
  *
- * @param {number} saturation Saturation.
+ * @param {number|undefined} saturation Saturation.
  */
 ol.layer.Base.prototype.setSaturation = function(saturation) {
   this.set(ol.layer.LayerProperty.SATURATION, saturation);
@@ -348,7 +353,7 @@ goog.exportProperty(
 
 
 /**
- * @param {boolean} visible Visible.
+ * @param {boolean|undefined} visible Visible.
  */
 ol.layer.Base.prototype.setVisible = function(visible) {
   this.set(ol.layer.LayerProperty.VISIBLE, visible);
diff --git a/src/ol/layer/layergroup.js b/src/ol/layer/layergroup.js
index 4e00e74c5d..89fb0b5256 100644
--- a/src/ol/layer/layergroup.js
+++ b/src/ol/layer/layergroup.js
@@ -142,11 +142,11 @@ ol.layer.Group.prototype.handleLayersRemove_ = function(collectionEvent) {
 
 
 /**
- * @return {ol.Collection} Collection of layers.
+ * @return {ol.Collection|undefined} Collection of layers.
  * @todo stability experimental
  */
 ol.layer.Group.prototype.getLayers = function() {
-  return /** @type {ol.Collection} */ (this.get(
+  return /** @type {ol.Collection|undefined} */ (this.get(
       ol.layer.GroupProperty.LAYERS));
 };
 goog.exportProperty(
@@ -156,7 +156,7 @@ goog.exportProperty(
 
 
 /**
- * @param {ol.Collection} layers Collection of layers.
+ * @param {ol.Collection|undefined} layers Collection of layers.
  * @todo stability experimental
  */
 ol.layer.Group.prototype.setLayers = function(layers) {
diff --git a/src/ol/layer/tilelayer.js b/src/ol/layer/tilelayer.js
index f8ba630d95..bb5c62e4cb 100644
--- a/src/ol/layer/tilelayer.js
+++ b/src/ol/layer/tilelayer.js
@@ -1,7 +1,6 @@
 goog.provide('ol.layer.Tile');
 
 goog.require('ol.layer.Layer');
-goog.require('ol.source.Tile');
 
 
 /**
@@ -44,14 +43,6 @@ goog.exportProperty(
     ol.layer.Tile.prototype.getPreload);
 
 
-/**
- * @return {ol.source.Tile} Source.
- */
-ol.layer.Tile.prototype.getTileSource = function() {
-  return /** @type {ol.source.Tile} */ (this.getSource());
-};
-
-
 /**
  * @param {number} preload Preload.
  * @todo stability experimental
diff --git a/src/ol/map.js b/src/ol/map.js
index 7caf96bcc0..a455b20d05 100644
--- a/src/ol/map.js
+++ b/src/ol/map.js
@@ -621,11 +621,16 @@ goog.exportProperty(
 
 /**
  * Get the collection of layers associated with this map.
- * @return {ol.Collection} Layers.
+ * @return {ol.Collection|undefined} Layers.
  * @todo stability experimental
  */
 ol.Map.prototype.getLayers = function() {
-  return this.getLayerGroup().getLayers();
+  var layerGroup = this.getLayerGroup();
+  if (goog.isDef(layerGroup)) {
+    return layerGroup.getLayers();
+  } else {
+    return undefined;
+  }
 };
 
 
@@ -661,7 +666,7 @@ goog.exportProperty(
 /**
  * Get the view associated with this map. This can be a 2D or 3D view. A 2D
  * view manages properties such as center and resolution.
- * @return {ol.View} View.
+ * @return {ol.View|undefined} View.
  * @todo stability experimental
  */
 ol.Map.prototype.getView = function() {
diff --git a/src/ol/proj/proj.js b/src/ol/proj/proj.js
index 1a686a9282..bcb3f31e2d 100644
--- a/src/ol/proj/proj.js
+++ b/src/ol/proj/proj.js
@@ -59,6 +59,7 @@ ol.METERS_PER_UNIT[ol.proj.Units.METERS] = 1;
 /**
  * @constructor
  * @param {olx.ProjectionOptions} options Projection options.
+ * @struct
  * @todo stability experimental
  */
 ol.proj.Projection = function(options) {
@@ -200,6 +201,7 @@ ol.proj.Projection.prototype.setDefaultTileGrid = function(tileGrid) {
  * @param {Proj4js.Proj} proj4jsProj Proj4js projection.
  * @param {olx.Proj4jsProjectionOptions} options Proj4js projection options.
  * @private
+ * @struct
  */
 ol.Proj4jsProjection_ = function(proj4jsProj, options) {
 
diff --git a/src/ol/renderer/canvas/canvasimagelayerrenderer.js b/src/ol/renderer/canvas/canvasimagelayerrenderer.js
index 7f5f477058..da01e396aa 100644
--- a/src/ol/renderer/canvas/canvasimagelayerrenderer.js
+++ b/src/ol/renderer/canvas/canvasimagelayerrenderer.js
@@ -1,5 +1,6 @@
 goog.provide('ol.renderer.canvas.ImageLayer');
 
+goog.require('goog.asserts');
 goog.require('goog.events');
 goog.require('goog.events.EventType');
 goog.require('goog.vec.Mat4');
@@ -9,6 +10,7 @@ goog.require('ol.ViewHint');
 goog.require('ol.layer.Image');
 goog.require('ol.renderer.Map');
 goog.require('ol.renderer.canvas.Layer');
+goog.require('ol.source.Image');
 
 
 
@@ -47,15 +49,6 @@ ol.renderer.canvas.ImageLayer.prototype.getImage = function() {
 };
 
 
-/**
- * @protected
- * @return {ol.layer.Image} Single image layer.
- */
-ol.renderer.canvas.ImageLayer.prototype.getImageLayer = function() {
-  return /** @type {ol.layer.Image} */ (this.getLayer());
-};
-
-
 /**
  * @inheritDoc
  */
@@ -76,8 +69,10 @@ ol.renderer.canvas.ImageLayer.prototype.renderFrame =
   var viewRotation = view2DState.rotation;
 
   var image;
-  var imageLayer = this.getImageLayer();
-  var imageSource = imageLayer.getImageSource();
+  var imageLayer = this.getLayer();
+  goog.asserts.assertInstanceof(imageLayer, ol.layer.Image);
+  var imageSource = imageLayer.getSource();
+  goog.asserts.assertInstanceof(imageSource, ol.source.Image);
 
   var hints = frameState.viewHints;
 
diff --git a/src/ol/renderer/canvas/canvasmaprenderer.js b/src/ol/renderer/canvas/canvasmaprenderer.js
index 9a20c3bedd..1df4741065 100644
--- a/src/ol/renderer/canvas/canvasmaprenderer.js
+++ b/src/ol/renderer/canvas/canvasmaprenderer.js
@@ -13,6 +13,7 @@ goog.require('ol.layer.Tile');
 goog.require('ol.layer.Vector');
 goog.require('ol.renderer.Map');
 goog.require('ol.renderer.canvas.ImageLayer');
+goog.require('ol.renderer.canvas.Layer');
 goog.require('ol.renderer.canvas.TileLayer');
 goog.require('ol.renderer.canvas.VectorLayer');
 goog.require('ol.source.State');
@@ -114,8 +115,8 @@ ol.renderer.canvas.Map.prototype.renderFrame = function(frameState) {
   for (i = 0, ii = layersArray.length; i < ii; ++i) {
 
     layer = layersArray[i];
-    layerRenderer =
-        /** @type {ol.renderer.canvas.Layer} */ (this.getLayerRenderer(layer));
+    layerRenderer = this.getLayerRenderer(layer);
+    goog.asserts.assertInstanceof(layerRenderer, ol.renderer.canvas.Layer);
     layerState = layerStates[goog.getUid(layer)];
     if (!layerState.visible ||
         layerState.sourceState != ol.source.State.READY ||
diff --git a/src/ol/renderer/canvas/canvastilelayerrenderer.js b/src/ol/renderer/canvas/canvastilelayerrenderer.js
index d445fbba87..3b7dbc7ba0 100644
--- a/src/ol/renderer/canvas/canvastilelayerrenderer.js
+++ b/src/ol/renderer/canvas/canvastilelayerrenderer.js
@@ -18,6 +18,7 @@ goog.require('ol.extent');
 goog.require('ol.layer.Tile');
 goog.require('ol.renderer.Map');
 goog.require('ol.renderer.canvas.Layer');
+goog.require('ol.source.Tile');
 
 
 
@@ -85,15 +86,6 @@ ol.renderer.canvas.TileLayer.prototype.getImage = function() {
 };
 
 
-/**
- * @protected
- * @return {ol.layer.Tile} Tile layer.
- */
-ol.renderer.canvas.TileLayer.prototype.getTileLayer = function() {
-  return /** @type {ol.layer.Tile} */ (this.getLayer());
-};
-
-
 /**
  * @inheritDoc
  */
@@ -174,8 +166,10 @@ ol.renderer.canvas.TileLayer.prototype.renderFrame =
   var view2DState = frameState.view2DState;
   var projection = view2DState.projection;
 
-  var tileLayer = this.getTileLayer();
-  var tileSource = tileLayer.getTileSource();
+  var tileLayer = this.getLayer();
+  goog.asserts.assertInstanceof(tileLayer, ol.layer.Tile);
+  var tileSource = tileLayer.getSource();
+  goog.asserts.assertInstanceof(tileSource, ol.source.Tile);
   var tileGrid = tileSource.getTileGrid();
   if (goog.isNull(tileGrid)) {
     tileGrid = ol.tilegrid.getForProjection(projection);
diff --git a/src/ol/renderer/dom/domimagelayerrenderer.js b/src/ol/renderer/dom/domimagelayerrenderer.js
index 8c8a3fa7c9..7d6be8b57a 100644
--- a/src/ol/renderer/dom/domimagelayerrenderer.js
+++ b/src/ol/renderer/dom/domimagelayerrenderer.js
@@ -1,5 +1,6 @@
 goog.provide('ol.renderer.dom.ImageLayer');
 
+goog.require('goog.asserts');
 goog.require('goog.dom');
 goog.require('goog.dom.TagName');
 goog.require('goog.events');
@@ -11,6 +12,7 @@ goog.require('ol.ViewHint');
 goog.require('ol.dom');
 goog.require('ol.layer.Image');
 goog.require('ol.renderer.dom.Layer');
+goog.require('ol.source.Image');
 
 
 
@@ -35,7 +37,7 @@ ol.renderer.dom.ImageLayer = function(mapRenderer, imageLayer) {
 
   /**
    * @private
-   * @type {goog.vec.Mat4.AnyType}
+   * @type {goog.vec.Mat4.Number}
    */
   this.transform_ = goog.vec.Mat4.createNumberIdentity();
 
@@ -43,15 +45,6 @@ ol.renderer.dom.ImageLayer = function(mapRenderer, imageLayer) {
 goog.inherits(ol.renderer.dom.ImageLayer, ol.renderer.dom.Layer);
 
 
-/**
- * @protected
- * @return {ol.layer.Image} Image layer.
- */
-ol.renderer.dom.ImageLayer.prototype.getImageLayer = function() {
-  return /** @type {ol.layer.Image} */ (this.getLayer());
-};
-
-
 /**
  * @inheritDoc
  */
@@ -64,8 +57,10 @@ ol.renderer.dom.ImageLayer.prototype.renderFrame =
   var viewRotation = view2DState.rotation;
 
   var image = this.image_;
-  var imageLayer = this.getImageLayer();
-  var imageSource = imageLayer.getImageSource();
+  var imageLayer = this.getLayer();
+  goog.asserts.assertInstanceof(imageLayer, ol.layer.Image);
+  var imageSource = imageLayer.getSource();
+  goog.asserts.assertInstanceof(imageSource, ol.source.Image);
 
   var hints = frameState.viewHints;
 
@@ -123,7 +118,7 @@ ol.renderer.dom.ImageLayer.prototype.renderFrame =
 
 
 /**
- * @param {goog.vec.Mat4.AnyType} transform Transform.
+ * @param {goog.vec.Mat4.Number} transform Transform.
  * @private
  */
 ol.renderer.dom.ImageLayer.prototype.setTransform_ = function(transform) {
diff --git a/src/ol/renderer/dom/dommaprenderer.js b/src/ol/renderer/dom/dommaprenderer.js
index f05b9326de..2e135d5192 100644
--- a/src/ol/renderer/dom/dommaprenderer.js
+++ b/src/ol/renderer/dom/dommaprenderer.js
@@ -9,6 +9,7 @@ goog.require('ol.layer.Image');
 goog.require('ol.layer.Tile');
 goog.require('ol.renderer.Map');
 goog.require('ol.renderer.dom.ImageLayer');
+goog.require('ol.renderer.dom.Layer');
 goog.require('ol.renderer.dom.TileLayer');
 goog.require('ol.source.State');
 
@@ -93,8 +94,8 @@ ol.renderer.dom.Map.prototype.renderFrame = function(frameState) {
   var layerKey;
   for (layerKey in this.getLayerRenderers()) {
     if (!(layerKey in layerStates)) {
-      layerRenderer = /** @type {ol.renderer.dom.Layer} */
-          (this.getLayerRendererByKey(layerKey));
+      layerRenderer = this.getLayerRendererByKey(layerKey);
+      goog.asserts.assertInstanceof(layerRenderer, ol.renderer.dom.Layer);
       goog.dom.removeNode(layerRenderer.getTarget());
     }
   }
diff --git a/src/ol/renderer/dom/domtilelayerrenderer.js b/src/ol/renderer/dom/domtilelayerrenderer.js
index 467efe6200..58936b2248 100644
--- a/src/ol/renderer/dom/domtilelayerrenderer.js
+++ b/src/ol/renderer/dom/domtilelayerrenderer.js
@@ -20,6 +20,7 @@ goog.require('ol.dom');
 goog.require('ol.extent');
 goog.require('ol.layer.Tile');
 goog.require('ol.renderer.dom.Layer');
+goog.require('ol.source.Tile');
 goog.require('ol.tilegrid.TileGrid');
 
 
@@ -65,15 +66,6 @@ ol.renderer.dom.TileLayer = function(mapRenderer, tileLayer) {
 goog.inherits(ol.renderer.dom.TileLayer, ol.renderer.dom.Layer);
 
 
-/**
- * @protected
- * @return {ol.layer.Tile} Tile layer.
- */
-ol.renderer.dom.TileLayer.prototype.getTileLayer = function() {
-  return /** @type {ol.layer.Tile} */ (this.getLayer());
-};
-
-
 /**
  * @inheritDoc
  */
@@ -91,8 +83,10 @@ ol.renderer.dom.TileLayer.prototype.renderFrame =
   var view2DState = frameState.view2DState;
   var projection = view2DState.projection;
 
-  var tileLayer = this.getTileLayer();
-  var tileSource = tileLayer.getTileSource();
+  var tileLayer = this.getLayer();
+  goog.asserts.assertInstanceof(tileLayer, ol.layer.Tile);
+  var tileSource = tileLayer.getSource();
+  goog.asserts.assertInstanceof(tileSource, ol.source.Tile);
   var tileGrid = tileSource.getTileGrid();
   if (goog.isNull(tileGrid)) {
     tileGrid = ol.tilegrid.getForProjection(projection);
@@ -312,7 +306,7 @@ ol.renderer.dom.TileLayerZ_ = function(tileGrid, tileCoordOrigin) {
 
   /**
    * @private
-   * @type {goog.vec.Mat4.AnyType}
+   * @type {goog.vec.Mat4.Number}
    */
   this.transform_ = goog.vec.Mat4.createNumberIdentity();
 
@@ -421,7 +415,7 @@ ol.renderer.dom.TileLayerZ_.prototype.removeTilesOutsideExtent =
 
 
 /**
- * @param {goog.vec.Mat4.AnyType} transform Transform.
+ * @param {goog.vec.Mat4.Number} transform Transform.
  */
 ol.renderer.dom.TileLayerZ_.prototype.setTransform = function(transform) {
   if (!goog.vec.Mat4.equals(transform, this.transform_)) {
diff --git a/src/ol/renderer/layerrenderer.js b/src/ol/renderer/layerrenderer.js
index a5cdc483d6..bd7ecd8e07 100644
--- a/src/ol/renderer/layerrenderer.js
+++ b/src/ol/renderer/layerrenderer.js
@@ -20,6 +20,8 @@ goog.require('ol.source.Tile');
  * @extends {goog.Disposable}
  * @param {ol.renderer.Map} mapRenderer Map renderer.
  * @param {ol.layer.Layer} layer Layer.
+ * @suppress {checkStructDictInheritance}
+ * @struct
  */
 ol.renderer.Layer = function(mapRenderer, layer) {
 
diff --git a/src/ol/renderer/maprenderer.js b/src/ol/renderer/maprenderer.js
index f02a33f6fd..7d9e75fc20 100644
--- a/src/ol/renderer/maprenderer.js
+++ b/src/ol/renderer/maprenderer.js
@@ -18,6 +18,8 @@ goog.require('ol.renderer.Layer');
  * @extends {goog.Disposable}
  * @param {Element} container Container.
  * @param {ol.Map} map Map.
+ * @suppress {checkStructDictInheritance}
+ * @struct
  */
 ol.renderer.Map = function(container, map) {
 
diff --git a/src/ol/renderer/webgl/webglimagelayerrenderer.js b/src/ol/renderer/webgl/webglimagelayerrenderer.js
index 0249e1c336..58cdddc483 100644
--- a/src/ol/renderer/webgl/webglimagelayerrenderer.js
+++ b/src/ol/renderer/webgl/webglimagelayerrenderer.js
@@ -12,6 +12,7 @@ goog.require('ol.ImageState');
 goog.require('ol.ViewHint');
 goog.require('ol.layer.Image');
 goog.require('ol.renderer.webgl.Layer');
+goog.require('ol.source.Image');
 
 
 
@@ -71,15 +72,6 @@ ol.renderer.webgl.ImageLayer.prototype.createTexture_ = function(image) {
 };
 
 
-/**
- * @protected
- * @return {ol.layer.Image} Tile layer.
- */
-ol.renderer.webgl.ImageLayer.prototype.getImageLayer = function() {
-  return /** @type {ol.layer.Image} */ (this.getLayer());
-};
-
-
 /**
  * @inheritDoc
  */
@@ -95,8 +87,10 @@ ol.renderer.webgl.ImageLayer.prototype.renderFrame =
 
   var image = this.image_;
   var texture = this.texture;
-  var imageLayer = this.getImageLayer();
-  var imageSource = imageLayer.getImageSource();
+  var imageLayer = this.getLayer();
+  goog.asserts.assertInstanceof(imageLayer, ol.layer.Image);
+  var imageSource = imageLayer.getSource();
+  goog.asserts.assertInstanceof(imageSource, ol.source.Image);
 
   var hints = frameState.viewHints;
 
diff --git a/src/ol/renderer/webgl/webglmapcolorshader.js b/src/ol/renderer/webgl/webglmapcolorshader.js
index 44bc6f212e..eeff8162d2 100644
--- a/src/ol/renderer/webgl/webglmapcolorshader.js
+++ b/src/ol/renderer/webgl/webglmapcolorshader.js
@@ -8,6 +8,7 @@ goog.require('ol.webgl.shader');
 /**
  * @constructor
  * @extends {ol.webgl.shader.Fragment}
+ * @struct
  */
 ol.renderer.webgl.map.shader.ColorFragment = function() {
   goog.base(this, ol.renderer.webgl.map.shader.ColorFragment.SOURCE);
@@ -43,6 +44,7 @@ ol.renderer.webgl.map.shader.ColorFragment.SOURCE = goog.DEBUG ?
 /**
  * @constructor
  * @extends {ol.webgl.shader.Vertex}
+ * @struct
  */
 ol.renderer.webgl.map.shader.ColorVertex = function() {
   goog.base(this, ol.renderer.webgl.map.shader.ColorVertex.SOURCE);
@@ -79,6 +81,7 @@ ol.renderer.webgl.map.shader.ColorVertex.SOURCE = goog.DEBUG ?
  * @constructor
  * @param {WebGLRenderingContext} gl GL.
  * @param {WebGLProgram} program Program.
+ * @struct
  */
 ol.renderer.webgl.map.shader.Color.Locations = function(gl, program) {
 
diff --git a/src/ol/renderer/webgl/webglmapdefaultshader.js b/src/ol/renderer/webgl/webglmapdefaultshader.js
index 8cf05e438f..47aff44a22 100644
--- a/src/ol/renderer/webgl/webglmapdefaultshader.js
+++ b/src/ol/renderer/webgl/webglmapdefaultshader.js
@@ -8,6 +8,7 @@ goog.require('ol.webgl.shader');
 /**
  * @constructor
  * @extends {ol.webgl.shader.Fragment}
+ * @struct
  */
 ol.renderer.webgl.map.shader.DefaultFragment = function() {
   goog.base(this, ol.renderer.webgl.map.shader.DefaultFragment.SOURCE);
@@ -43,6 +44,7 @@ ol.renderer.webgl.map.shader.DefaultFragment.SOURCE = goog.DEBUG ?
 /**
  * @constructor
  * @extends {ol.webgl.shader.Vertex}
+ * @struct
  */
 ol.renderer.webgl.map.shader.DefaultVertex = function() {
   goog.base(this, ol.renderer.webgl.map.shader.DefaultVertex.SOURCE);
@@ -79,6 +81,7 @@ ol.renderer.webgl.map.shader.DefaultVertex.SOURCE = goog.DEBUG ?
  * @constructor
  * @param {WebGLRenderingContext} gl GL.
  * @param {WebGLProgram} program Program.
+ * @struct
  */
 ol.renderer.webgl.map.shader.Default.Locations = function(gl, program) {
 
diff --git a/src/ol/renderer/webgl/webglmaprenderer.js b/src/ol/renderer/webgl/webglmaprenderer.js
index 1dc503ef90..a99699aa9c 100644
--- a/src/ol/renderer/webgl/webglmaprenderer.js
+++ b/src/ol/renderer/webgl/webglmaprenderer.js
@@ -20,6 +20,7 @@ goog.require('ol.layer.Image');
 goog.require('ol.layer.Tile');
 goog.require('ol.renderer.Map');
 goog.require('ol.renderer.webgl.ImageLayer');
+goog.require('ol.renderer.webgl.Layer');
 goog.require('ol.renderer.webgl.TileLayer');
 goog.require('ol.renderer.webgl.map.shader.Color');
 goog.require('ol.renderer.webgl.map.shader.Default');
@@ -520,6 +521,7 @@ ol.renderer.webgl.Map.prototype.handleWebGLContextLost = function(event) {
   this.textureCache_.clear();
   this.textureCacheFrameMarkerCount_ = 0;
   goog.object.forEach(this.getLayerRenderers(), function(layerRenderer) {
+    goog.asserts.assertInstanceof(layerRenderer, ol.renderer.webgl.Layer);
     layerRenderer.handleWebGLContextLost();
   });
 };
@@ -596,6 +598,7 @@ ol.renderer.webgl.Map.prototype.renderFrame = function(frameState) {
   for (i = 0, ii = layersArray.length; i < ii; ++i) {
     layer = layersArray[i];
     layerRenderer = this.getLayerRenderer(layer);
+    goog.asserts.assertInstanceof(layerRenderer, ol.renderer.webgl.Layer);
     layerState = frameState.layerStates[goog.getUid(layer)];
     if (layerState.visible &&
         layerState.sourceState == ol.source.State.READY &&
@@ -682,6 +685,7 @@ ol.renderer.webgl.Map.prototype.renderFrame = function(frameState) {
     }
 
     layerRenderer = this.getLayerRenderer(layer);
+    goog.asserts.assertInstanceof(layerRenderer, ol.renderer.webgl.Layer);
     gl.uniformMatrix4fv(
         locations.u_texCoordMatrix, false, layerRenderer.getTexCoordMatrix());
     gl.uniformMatrix4fv(locations.u_projectionMatrix, false,
diff --git a/src/ol/renderer/webgl/webgltilelayerrenderer.js b/src/ol/renderer/webgl/webgltilelayerrenderer.js
index 31a25952fb..64f836c862 100644
--- a/src/ol/renderer/webgl/webgltilelayerrenderer.js
+++ b/src/ol/renderer/webgl/webgltilelayerrenderer.js
@@ -4,6 +4,7 @@
 goog.provide('ol.renderer.webgl.TileLayer');
 
 goog.require('goog.array');
+goog.require('goog.asserts');
 goog.require('goog.object');
 goog.require('goog.vec.Mat4');
 goog.require('goog.vec.Vec4');
@@ -16,6 +17,7 @@ goog.require('ol.layer.Tile');
 goog.require('ol.math');
 goog.require('ol.renderer.webgl.Layer');
 goog.require('ol.renderer.webgl.tilelayer.shader');
+goog.require('ol.source.Tile');
 goog.require('ol.structs.Buffer');
 
 
@@ -92,15 +94,6 @@ ol.renderer.webgl.TileLayer.prototype.disposeInternal = function() {
 };
 
 
-/**
- * @protected
- * @return {ol.layer.Tile} Tile layer.
- */
-ol.renderer.webgl.TileLayer.prototype.getTileLayer = function() {
-  return /** @type {ol.layer.Tile} */ (this.getLayer());
-};
-
-
 /**
  * @inheritDoc
  */
@@ -122,8 +115,10 @@ ol.renderer.webgl.TileLayer.prototype.renderFrame =
   var view2DState = frameState.view2DState;
   var projection = view2DState.projection;
 
-  var tileLayer = this.getTileLayer();
-  var tileSource = tileLayer.getTileSource();
+  var tileLayer = this.getLayer();
+  goog.asserts.assertInstanceof(tileLayer, ol.layer.Tile);
+  var tileSource = tileLayer.getSource();
+  goog.asserts.assertInstanceof(tileSource, ol.source.Tile);
   var tileGrid = tileSource.getTileGrid();
   if (goog.isNull(tileGrid)) {
     tileGrid = ol.tilegrid.getForProjection(projection);
diff --git a/src/ol/renderer/webgl/webgltilelayershader.js b/src/ol/renderer/webgl/webgltilelayershader.js
index 8d8169042c..6cbb58103b 100644
--- a/src/ol/renderer/webgl/webgltilelayershader.js
+++ b/src/ol/renderer/webgl/webgltilelayershader.js
@@ -8,6 +8,7 @@ goog.require('ol.webgl.shader');
 /**
  * @constructor
  * @extends {ol.webgl.shader.Fragment}
+ * @struct
  */
 ol.renderer.webgl.tilelayer.shader.Fragment = function() {
   goog.base(this, ol.renderer.webgl.tilelayer.shader.Fragment.SOURCE);
@@ -43,6 +44,7 @@ ol.renderer.webgl.tilelayer.shader.Fragment.SOURCE = goog.DEBUG ?
 /**
  * @constructor
  * @extends {ol.webgl.shader.Vertex}
+ * @struct
  */
 ol.renderer.webgl.tilelayer.shader.Vertex = function() {
   goog.base(this, ol.renderer.webgl.tilelayer.shader.Vertex.SOURCE);
@@ -79,6 +81,7 @@ ol.renderer.webgl.tilelayer.shader.Vertex.SOURCE = goog.DEBUG ?
  * @constructor
  * @param {WebGLRenderingContext} gl GL.
  * @param {WebGLProgram} program Program.
+ * @struct
  */
 ol.renderer.webgl.tilelayer.shader.Locations = function(gl, program) {
 
diff --git a/src/ol/source/imagewmssource.js b/src/ol/source/imagewmssource.js
index 6f7d6ddd2a..dcc3596e8d 100644
--- a/src/ol/source/imagewmssource.js
+++ b/src/ol/source/imagewmssource.js
@@ -109,7 +109,9 @@ ol.source.ImageWMS.prototype.getFeatureInfoForPixel =
   var size = map.getSize();
   goog.asserts.assert(goog.isDefAndNotNull(size));
   var extent = view.calculateExtent(size);
-  var url = this.imageUrlFunction(extent, size, view.getProjection());
+  var projection = view.getProjection();
+  goog.asserts.assert(goog.isDef(projection));
+  var url = this.imageUrlFunction(extent, size, projection);
   goog.asserts.assert(goog.isDef(url),
       'ol.source.ImageWMS#imageUrlFunction does not return a URL');
   ol.source.wms.getFeatureInfo(url, pixel, this.getFeatureInfoOptions_, success,
diff --git a/src/ol/source/tilewmssource.js b/src/ol/source/tilewmssource.js
index 7f5e849cbb..67cb7467f5 100644
--- a/src/ol/source/tilewmssource.js
+++ b/src/ol/source/tilewmssource.js
@@ -157,11 +157,13 @@ ol.source.TileWMS.prototype.getFeatureInfoForPixel =
     function(pixel, map, success, opt_error) {
   var coord = map.getCoordinateFromPixel(pixel),
       view2D = map.getView().getView2D(),
-      projection = view2D.getProjection(),
-      tileGrid = goog.isNull(this.tileGrid) ?
-          ol.tilegrid.getForProjection(projection) : this.tileGrid,
-      tileCoord = tileGrid.getTileCoordForCoordAndResolution(coord,
-          view2D.getResolution()),
+      projection = view2D.getProjection();
+  goog.asserts.assert(goog.isDef(projection));
+  var tileGrid = goog.isNull(this.tileGrid) ?
+          ol.tilegrid.getForProjection(projection) : this.tileGrid;
+  var resolution = view2D.getResolution();
+  goog.asserts.assert(goog.isDef(resolution));
+  var tileCoord = tileGrid.getTileCoordForCoordAndResolution(coord, resolution),
       tileExtent = tileGrid.getTileCoordExtent(tileCoord),
       offset = map.getPixelFromCoordinate(ol.extent.getTopLeft(tileExtent)),
       url = this.tileUrlFunction(tileCoord, projection);
diff --git a/src/ol/structs/buffer.js b/src/ol/structs/buffer.js
index 1a3aad615f..b18052ffe3 100644
--- a/src/ol/structs/buffer.js
+++ b/src/ol/structs/buffer.js
@@ -28,6 +28,7 @@ ol.BUFFER_REPLACE_UNUSED_ENTRIES_WITH_NANS = goog.DEBUG;
  * @param {Array.<number>=} opt_arr Array.
  * @param {number=} opt_used Used.
  * @param {number=} opt_usage Usage.
+ * @struct
  * @todo stability experimental
  */
 ol.structs.Buffer = function(opt_arr, opt_used, opt_usage) {
diff --git a/src/ol/structs/integerset.js b/src/ol/structs/integerset.js
index 17fc2ebc53..dc292443eb 100644
--- a/src/ol/structs/integerset.js
+++ b/src/ol/structs/integerset.js
@@ -9,6 +9,7 @@ goog.require('goog.asserts');
  * This implementation is designed for the case when the number of distinct
  * integer ranges is small.
  * @constructor
+ * @struct
  * @param {Array.<number>=} opt_arr Array.
  */
 ol.structs.IntegerSet = function(opt_arr) {
diff --git a/src/ol/structs/lrucache.js b/src/ol/structs/lrucache.js
index 12e8e5d49c..3fc7a2427d 100644
--- a/src/ol/structs/lrucache.js
+++ b/src/ol/structs/lrucache.js
@@ -10,6 +10,7 @@ goog.require('goog.object');
  * Object's properties (e.g. 'hasOwnProperty' is not allowed as a key). Expiring
  * items from the cache is the responsibility of the user.
  * @constructor
+ * @struct
  * @template T
  */
 ol.structs.LRUCache = function() {
diff --git a/src/ol/structs/priorityqueue.js b/src/ol/structs/priorityqueue.js
index b303d6c64c..72b4019475 100644
--- a/src/ol/structs/priorityqueue.js
+++ b/src/ol/structs/priorityqueue.js
@@ -17,6 +17,7 @@ goog.require('goog.object');
  * @constructor
  * @param {function(T): number} priorityFunction Priority function.
  * @param {function(T): string} keyFunction Key function.
+ * @struct
  * @template T
  */
 ol.structs.PriorityQueue = function(priorityFunction, keyFunction) {
diff --git a/src/ol/structs/rbush.js b/src/ol/structs/rbush.js
index 3be4c3a03b..8f45d27cb6 100644
--- a/src/ol/structs/rbush.js
+++ b/src/ol/structs/rbush.js
@@ -36,6 +36,7 @@ goog.require('ol.extent');
  * @param {number} height Height.
  * @param {Array.<ol.structs.RBushNode.<T>>} children Children.
  * @param {?T} value Value.
+ * @struct
  * @template T
  */
 ol.structs.RBushNode = function(extent, height, children, value) {
@@ -160,6 +161,7 @@ ol.structs.RBushNode.prototype.isLeaf = function() {
  * @constructor
  * @param {number=} opt_maxEntries Max entries.
  * @see https://github.com/mourner/rbush
+ * @struct
  * @template T
  */
 ol.structs.RBush = function(opt_maxEntries) {
diff --git a/src/ol/tilecache.js b/src/ol/tilecache.js
index baca04fb4a..643ed75ce9 100644
--- a/src/ol/tilecache.js
+++ b/src/ol/tilecache.js
@@ -18,6 +18,7 @@ ol.DEFAULT_TILE_CACHE_HIGH_WATER_MARK = 2048;
  * @constructor
  * @extends {ol.structs.LRUCache.<ol.Tile>}
  * @param {number=} opt_highWaterMark High water mark.
+ * @struct
  */
 ol.TileCache = function(opt_highWaterMark) {
 
diff --git a/src/ol/tilegrid/tilegrid.js b/src/ol/tilegrid/tilegrid.js
index 08ee4e4614..36950abc08 100644
--- a/src/ol/tilegrid/tilegrid.js
+++ b/src/ol/tilegrid/tilegrid.js
@@ -28,6 +28,7 @@ ol.DEFAULT_MAX_ZOOM = 42;
 /**
  * @constructor
  * @param {olx.tilegrid.TileGridOptions} options Tile grid options.
+ * @struct
  * @todo stability experimental
  */
 ol.tilegrid.TileGrid = function(options) {
diff --git a/src/ol/tilegrid/wmtstilegrid.js b/src/ol/tilegrid/wmtstilegrid.js
index 3393aced51..e91427a43a 100644
--- a/src/ol/tilegrid/wmtstilegrid.js
+++ b/src/ol/tilegrid/wmtstilegrid.js
@@ -11,6 +11,7 @@ goog.require('ol.tilegrid.TileGrid');
  * @constructor
  * @extends {ol.tilegrid.TileGrid}
  * @param {olx.tilegrid.WMTSOptions} options WMTS options.
+ * @struct
  * @todo stability experimental
  */
 ol.tilegrid.WMTS = function(options) {
diff --git a/src/ol/tilegrid/xyztilegrid.js b/src/ol/tilegrid/xyztilegrid.js
index 6325d3602b..239e282bc8 100644
--- a/src/ol/tilegrid/xyztilegrid.js
+++ b/src/ol/tilegrid/xyztilegrid.js
@@ -13,6 +13,7 @@ goog.require('ol.tilegrid.TileGrid');
  * @constructor
  * @extends {ol.tilegrid.TileGrid}
  * @param {olx.tilegrid.XYZOptions} options XYZ options.
+ * @struct
  * @todo stability experimental
  */
 ol.tilegrid.XYZ = function(options) {
diff --git a/src/ol/tilequeue.js b/src/ol/tilequeue.js
index 57d0791caa..e0426a5cb4 100644
--- a/src/ol/tilequeue.js
+++ b/src/ol/tilequeue.js
@@ -22,6 +22,7 @@ ol.TilePriorityFunction;
  *     Tile priority function.
  * @param {function(): ?} tileChangeCallback
  *     Function called on each tile change event.
+ * @struct
  */
 ol.TileQueue = function(tilePriorityFunction, tileChangeCallback) {
 
diff --git a/src/ol/tilerange.js b/src/ol/tilerange.js
index a53723ed53..cf09683c53 100644
--- a/src/ol/tilerange.js
+++ b/src/ol/tilerange.js
@@ -15,6 +15,7 @@ goog.require('ol.TileCoord');
  * @param {number} maxX Maximum X.
  * @param {number} minY Minimum Y.
  * @param {number} maxY Maximum Y.
+ * @struct
  */
 ol.TileRange = function(minX, maxX, minY, maxY) {
 
diff --git a/src/ol/vec/mat4.js b/src/ol/vec/mat4.js
index c6dae319a1..faba66a6f0 100644
--- a/src/ol/vec/mat4.js
+++ b/src/ol/vec/mat4.js
@@ -97,7 +97,7 @@ ol.vec.Mat4.makeSaturation = function(matrix, value) {
  * transformed vector into resultVec. The input vector is multiplied against the
  * upper 2x4 matrix omitting the projective component.
  *
- * @param {goog.vec.Mat4.AnyType} mat The matrix supplying the transformation.
+ * @param {goog.vec.Mat4.Number} mat The matrix supplying the transformation.
  * @param {Array.<number>} vec The 3 element vector to transform.
  * @param {Array.<number>} resultVec The 3 element vector to receive the results
  *     (may be vec).
diff --git a/src/ol/view.js b/src/ol/view.js
index 9d727e3b4d..ffee86ba59 100644
--- a/src/ol/view.js
+++ b/src/ol/view.js
@@ -47,13 +47,31 @@ ol.View.prototype.getHints = function() {
 /**
  * @inheritDoc
  */
-ol.View.prototype.getView2D = goog.abstractMethod;
+ol.View.prototype.getView2D = function() {
+  // FIXME for some reason, we can't use goog.abstractMethod here
+  goog.asserts.fail();
+  return null;
+};
 
 
 /**
  * @inheritDoc
  */
-ol.View.prototype.getView3D = goog.abstractMethod;
+ol.View.prototype.getView3D = function() {
+  // FIXME for some reason, we can't use goog.abstractMethod here
+  goog.asserts.fail();
+  return null;
+};
+
+
+/**
+ * @inheritDoc
+ */
+ol.View.prototype.isDef = function() {
+  // FIXME for some reason, we can't use goog.abstractMethod here
+  goog.asserts.fail();
+  return false;
+};
 
 
 /**
diff --git a/src/ol/webgl/shader.js b/src/ol/webgl/shader.js
index a06fd5c401..f9a2271724 100644
--- a/src/ol/webgl/shader.js
+++ b/src/ol/webgl/shader.js
@@ -9,6 +9,7 @@ goog.require('ol.webgl');
 /**
  * @constructor
  * @param {string} source Source.
+ * @struct
  */
 ol.webgl.Shader = function(source) {
 
@@ -46,6 +47,7 @@ ol.webgl.Shader.prototype.isAnimated = goog.functions.FALSE;
  * @constructor
  * @extends {ol.webgl.Shader}
  * @param {string} source Source.
+ * @struct
  */
 ol.webgl.shader.Fragment = function(source) {
   goog.base(this, source);
@@ -66,6 +68,7 @@ ol.webgl.shader.Fragment.prototype.getType = function() {
  * @constructor
  * @extends {ol.webgl.Shader}
  * @param {string} source Source.
+ * @struct
  */
 ol.webgl.shader.Vertex = function(source) {
   goog.base(this, source);
diff --git a/src/ol/webgl/shader.mustache b/src/ol/webgl/shader.mustache
index 14ecdd6947..ed62dc9718 100644
--- a/src/ol/webgl/shader.mustache
+++ b/src/ol/webgl/shader.mustache
@@ -8,6 +8,7 @@ goog.require('ol.webgl.shader');
 /**
  * @constructor
  * @extends {ol.webgl.shader.Fragment}
+ * @struct
  */
 {{className}}Fragment = function() {
   goog.base(this, {{className}}Fragment.SOURCE);
@@ -43,6 +44,7 @@ goog.addSingletonGetter({{className}}Fragment);
 /**
  * @constructor
  * @extends {ol.webgl.shader.Vertex}
+ * @struct
  */
 {{className}}Vertex = function() {
   goog.base(this, {{className}}Vertex.SOURCE);
@@ -79,6 +81,7 @@ goog.addSingletonGetter({{className}}Vertex);
  * @constructor
  * @param {WebGLRenderingContext} gl GL.
  * @param {WebGLProgram} program Program.
+ * @struct
  */
 {{namespace}}.Locations = function(gl, program) {
 {{#getUniforms}}