For ITK rev. 3.8 and earlier: Converting coordinates from the ITK physical coordinate system (which did not support rotated images for ITK v3.8 and earlier) to the MITK world coordinate system should be performed via the Geometry3D of the Image, see Geometry3D::WorldToItkPhysicalPoint.
(as of 2015_05) GLMappers are no longer supported in the rendering pipeline. Please use mitkVtkMapper instead or consider writing your own vtk classes, such as vtkActor or vtkMapper