fix Globe.getHeight function

better handling of under ellipsoid surface terrain
CesiumGS · Nov 7, 2016 · 9f7d911 · 9f7d911
1 parent ead79f4
commit 9f7d911
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Showing 2 changed files with 19 additions and 4 deletions.
diff --git a/Source/Scene/Globe.js b/Source/Scene/Globe.js
@@ -430,7 +430,16 @@ define([
         var cartesian = ellipsoid.cartographicToCartesian(cartographic, scratchGetHeightCartesian);
 
         var ray = scratchGetHeightRay;
-        Cartesian3.normalize(cartesian, ray.direction);
+        var surfaceNormal = ellipsoid.geodeticSurfaceNormal(cartesian, ray.direction);
+
+        // compute origin point, to account for a case where the terrain is under ellipsoid surface
+        var minimumHeight = Math.min(defaultValue(tile.data.minimumHeight, 0.0), 0.0);
+
+        // take into account the position height
+        minimumHeight -= cartographic.height;
+
+        var minimumHeightVector = Cartesian3.multiplyByScalar(surfaceNormal, minimumHeight - 1.0, scratchGetHeightIntersection);
+        Cartesian3.add(cartesian, minimumHeightVector, ray.origin);
 
         var intersection = tile.data.pick(ray, undefined, undefined, false, scratchGetHeightIntersection);
         if (!defined(intersection)) {

diff --git a/Source/Scene/QuadtreePrimitive.js b/Source/Scene/QuadtreePrimitive.js
@@ -632,9 +632,15 @@ define([
 
                     if (mode === SceneMode.SCENE3D) {
                         var surfaceNormal = ellipsoid.geodeticSurfaceNormal(data.position, scratchRay.direction);
-                        // subtract by earth minor axis radius, to account for a case where the terrain is under ellipsoid surface - is that OK or should I use lower value (maybe -11500.0 which appears some lines bellow)?
-                        var radiusLengthVector = Cartesian3.multiplyByScalar(surfaceNormal, ellipsoid.minimumRadius, scratchPosition);
-                        Cartesian3.subtract(data.position, radiusLengthVector, scratchRay.origin);
+
+                        // compute origin point, to account for a case where the terrain is under ellipsoid surface
+                        var minimumHeight = Math.min(defaultValue(tile.data.minimumHeight, 0.0), 0.0);
+
+                        // take into account the position height
+                        minimumHeight -= data.positionCartographic.height;
+
+                        var minimumHeightVector = Cartesian3.multiplyByScalar(surfaceNormal, minimumHeight - 1.0, scratchPosition);
+                        Cartesian3.add(data.position, minimumHeightVector, scratchRay.origin);
                     } else {
                         Cartographic.clone(data.positionCartographic, scratchCartographic);