Hi,
the getHeightAtCoordinates() method seems to be broken in the 2.4 CDN and 2.5 preview version:
http://www.babylonjs-playground.com/#1JXJVF#5
(Please wait 2-5 seconds to see the box floating way above the ground)
http://jerome.bousquie.fr/BJS/demos/getHeightAtCoordinates.html