Fix terrain exaggeration bug

CHANGES.md

@@ -19,6 +19,7 @@ Change Log
 * Fix issue where the `GroundPrimitive` volume was being clipped by the far plane. [#3706](https://github.com/AnalyticalGraphicsInc/cesium/issues/3706)
 * Fixed issue where `Camera.computeViewRectangle` was incorrect when crossing the international date line [#3717](https://github.com/AnalyticalGraphicsInc/cesium/issues/3717)
 * Added `Rectangle` result parameter to `Camera.computeViewRectangle`
+* Fix bug when upsampling exaggerated terrain where the terrain heights were exaggerated at twice the value. [#3607](https://github.com/AnalyticalGraphicsInc/cesium/issues/3607)
 
 ### 1.19 - 2016-03-01
 

Source/Core/HeightmapTerrainData.js

@@ -226,7 +226,8 @@ define([
                     result.occludeePointInScaledSpace,
                     6,
                     result.orientedBoundingBox,
-                    TerrainEncoding.clone(result.encoding));
+                    TerrainEncoding.clone(result.encoding),
+                    exaggeration);
 
             // Free memory received from server after mesh is created.
             that._buffer = undefined;
@@ -261,7 +262,8 @@ define([
             var buffer = this._mesh.vertices;
             var encoding = this._mesh.encoding;
             var skirtHeight = this._skirtHeight;
-            heightSample = interpolateMeshHeight(buffer, encoding, heightOffset, heightScale, skirtHeight, rectangle, width, height, longitude, latitude);
+            var exaggeration = this._mesh.exaggeration;
+            heightSample = interpolateMeshHeight(buffer, encoding, heightOffset, heightScale, skirtHeight, rectangle, width, height, longitude, latitude, exaggeration);
         } else {
             heightSample = interpolateHeight(this._buffer, elementsPerHeight, elementMultiplier, stride, isBigEndian, rectangle, width, height, longitude, latitude);
             heightSample = heightSample * heightScale + heightOffset;
@@ -335,6 +337,7 @@ define([
 
         var heightOffset = structure.heightOffset;
         var heightScale = structure.heightScale;
+        var exaggeration = meshData.exaggeration;
 
         var elementsPerHeight = structure.elementsPerHeight;
         var elementMultiplier = structure.elementMultiplier;
@@ -346,7 +349,7 @@ define([
             var latitude = CesiumMath.lerp(destinationRectangle.north, destinationRectangle.south, j / (height - 1));
             for (var i = 0; i < width; ++i) {
                 var longitude = CesiumMath.lerp(destinationRectangle.west, destinationRectangle.east, i / (width - 1));
-                var heightSample = interpolateMeshHeight(buffer, encoding, heightOffset, heightScale, skirtHeight, sourceRectangle, width, height, longitude, latitude);
+                var heightSample = interpolateMeshHeight(buffer, encoding, heightOffset, heightScale, skirtHeight, sourceRectangle, width, height, longitude, latitude, exaggeration);
                 setHeight(heights, elementsPerHeight, elementMultiplier, divisor, stride, isBigEndian, j * width + i, heightSample);
             }
         }
@@ -444,7 +447,7 @@ define([
         return triangleInterpolateHeight(dx, dy, southwestHeight, southeastHeight, northwestHeight, northeastHeight);
     }
 
-    function interpolateMeshHeight(buffer, encoding, heightOffset, heightScale, skirtHeight, sourceRectangle, width, height, longitude, latitude) {
+    function interpolateMeshHeight(buffer, encoding, heightOffset, heightScale, skirtHeight, sourceRectangle, width, height, longitude, latitude, exaggeration) {
         var fromWest = (longitude - sourceRectangle.west) * (width - 1) / (sourceRectangle.east - sourceRectangle.west);
         var fromSouth = (latitude - sourceRectangle.south) * (height - 1) / (sourceRectangle.north - sourceRectangle.south);
 
@@ -478,10 +481,10 @@ define([
         southInteger = height - 1 - southInteger;
         northInteger = height - 1 - northInteger;
 
-        var southwestHeight = (encoding.decodeHeight(buffer, southInteger * width + westInteger) - heightOffset) / heightScale;
-        var southeastHeight = (encoding.decodeHeight(buffer, southInteger * width + eastInteger) - heightOffset) / heightScale;
-        var northwestHeight = (encoding.decodeHeight(buffer, northInteger * width + westInteger) - heightOffset) / heightScale;
-        var northeastHeight = (encoding.decodeHeight(buffer, northInteger * width + eastInteger) - heightOffset) / heightScale;
+        var southwestHeight = (encoding.decodeHeight(buffer, southInteger * width + westInteger) / exaggeration - heightOffset) / heightScale;
+        var southeastHeight = (encoding.decodeHeight(buffer, southInteger * width + eastInteger) / exaggeration - heightOffset) / heightScale;
+        var northwestHeight = (encoding.decodeHeight(buffer, northInteger * width + westInteger) / exaggeration - heightOffset) / heightScale;
+        var northeastHeight = (encoding.decodeHeight(buffer, northInteger * width + eastInteger) / exaggeration - heightOffset) / heightScale;
 
         return triangleInterpolateHeight(dx, dy, southwestHeight, southeastHeight, northwestHeight, northeastHeight);
     }

Source/Core/QuantizedMeshTerrainData.js

@@ -320,7 +320,8 @@ define([
                     occlusionPoint,
                     stride,
                     obb,
-                    terrainEncoding);
+                    terrainEncoding,
+                    exaggeration);
 
             // Free memory received from server after mesh is created.
             that._quantizedVertices = undefined;
@@ -408,7 +409,8 @@ define([
             isEastChild : isEastChild,
             isNorthChild : isNorthChild,
             childRectangle : childRectangle,
-            ellipsoid : ellipsoid
+            ellipsoid : ellipsoid,
+            exaggeration : mesh.exaggeration
         });
 
         if (!defined(upsamplePromise)) {

Source/Core/TerrainMesh.js

@@ -30,7 +30,7 @@ define([
       *
       * @private
       */
-    function TerrainMesh(center, vertices, indices, minimumHeight, maximumHeight, boundingSphere3D, occludeePointInScaledSpace, vertexStride, orientedBoundingBox, encoding) {
+    function TerrainMesh(center, vertices, indices, minimumHeight, maximumHeight, boundingSphere3D, occludeePointInScaledSpace, vertexStride, orientedBoundingBox, encoding, exaggeration) {
         /**
          * The center of the tile.  Vertex positions are specified relative to this center.
          * @type {Cartesian3}
@@ -98,6 +98,12 @@ define([
          * @type {TerrainEncoding}
          */
         this.encoding = encoding;
+
+        /**
+         * The amount that this mesh was exaggerated.
+         * @type {Number}
+         */
+        this.exaggeration = exaggeration;
     }
 
     return TerrainMesh;

Source/Workers/upsampleQuantizedTerrainMesh.js

@@ -80,6 +80,7 @@ define([
 
         var encoding = TerrainEncoding.clone(parameters.encoding);
         var hasVertexNormals = encoding.hasVertexNormals;
+        var exaggeration = parameters.exaggeration;
 
         var vertexCount = 0;
         var quantizedVertexCount = parameters.vertexCountWithoutSkirts;
@@ -98,7 +99,7 @@ define([
         var i, n;
         for (i = 0, n = 0; i < quantizedVertexCount; ++i, n += 2) {
             var texCoords = encoding.decodeTextureCoordinates(parentVertices, i, decodeTexCoordsScratch);
-            height  = encoding.decodeHeight(parentVertices, i);
+            height  = encoding.decodeHeight(parentVertices, i) / exaggeration;
 
             parentUBuffer[i] = CesiumMath.clamp((texCoords.x * maxShort) | 0, 0, maxShort);
             parentVBuffer[i] = CesiumMath.clamp((texCoords.y * maxShort) | 0, 0, maxShort);