Merge pull request #6220 from likangning93/cbrt

Math.cbrt -> Math.pow

Author: lilleyse

CHANGES.md

@@ -9,6 +9,7 @@ Change Log
 ##### Fixes :wrench:
 * Fixed bug where AxisAlignedBoundingBox did not copy over center value when cloning an undefined result. [#6183](https://github.com/AnalyticalGraphicsInc/cesium/pull/6183)
 * Fixed `Resource.fetch` when called with no arguments [#6206](https://github.com/AnalyticalGraphicsInc/cesium/issues/6206)
+* Fixed bug where 3D Tiles Point Clouds would fail in Internet Explorer. [#6220](https://github.com/AnalyticalGraphicsInc/cesium/pull/6220)
 
 ##### Additions :tada:
 * Enable terrain in the `CesiumViewer` demo application [#6198](https://github.com/AnalyticalGraphicsInc/cesium/pull/6198)

Source/Scene/PointCloud3DTileContent.js

@@ -466,7 +466,7 @@ define([
         // Typical use case is leaves, where lower estimates of interpoint distance might
         // lead to underattenuation.
         var sphereVolume = content._tile.contentBoundingVolume.boundingSphere.volume();
-        content._baseResolutionApproximation = Math.cbrt(sphereVolume / pointsLength);
+        content._baseResolutionApproximation = Math.pow(sphereVolume / pointsLength, 1/3); // IE doesn't support cbrt
     }
 
     var scratchPointSizeAndTilesetTimeAndGeometricErrorAndDepthMultiplier = new Cartesian4();