Finding the real coordinates of a point on the finest grid

[dmingram66]

I need to find the real world (x,y,z) coordinates of a point in a box on the finest level of refinement. Trying to use ```geom.CellCenter()''' results in a real coordinate which is not inside the computational domain (I assume it's using the wrong value of dx.

Google suggests that ```geom[level].CellCenter()''' will work but I just get errors saying geom doesn't support [level].

Help would be appreciated.

[WeiqunZhang]

This appears to be a follow-up of #5508. If so, could you move the discussion there? The detail and context matter.