first up: awesome work Cesium crew, really great stuff the v28 release is noticeably faster for us displaying vectors and the new terrain is great.
our current problem relates to apparently different behavior between (globe and 2d view) and columbus view. we are adding billboards to a billboard collection using mouse clicks. inspired by the extent dragging example in the sandbox we use:
var cartesian = scene.camera.pickEllipsoid(movement.position, ellipsoid);
to get the world coords of the mouse click.
this works for globe and 2d, but in columbus view the points are floating high in the sky, instead of appearing on the surface. maybe they think they are in globe mode ? interestingly, flicking the map to globe (or 2d) and then back to columbus results in the points being correctly placed on the surface.
is this a bug, should i file a bug report ?