Data items in the IHM_2DEM_CLASS_AVERAGE_FITTING category records the
               details of the fitting of the model to the 2DEM class averages 
               used in the IHM modeling. The following conventions are recommended 
               while generating the rotation matrix and translation vector for
               transformation. 
              
               - The model is rotated and translated to fit to the 2DEM image. 
               - The 2DEM image should be in the XY plane.  
               - The lower left image corner (image pixel index 0,0) should be at x,y,z = (0,0,0).
               - The 2D image is scaled by the _ihm_2dem_class_average_restraint.pixel_size_width 
                 and _ihm_2dem_class_average_restraint.pixel_size_height from the 
                 IHM_2DEM_CLASS_AVERAGE_RESTRAINT table.
               - The transformation is applied after the scaling and hence the translation vector 
                 should account for the scaling.
               - There are no specifications for Z translations i.e., how far the image should be 
                 from the model while projecting. It may be set to zero.