Recently, I purchased realviz imagemodeler 3; but when I try to open the file from the previous version of imagemodeler 2.1.2, the file type 'IMF' option does not exist.

in IM2.x export to *.rz3, wich exports points and camera

Hello,
no there is no import of rz3 in IM 3.
the way to do this is to export as RZML from IM 2.1, which is readable in IM3.
 
run regedit
go to:
HKEY_CURRENT_USER/Software/REALVIZ/ImageModeler/Preferences/
 
Then: Edit -> New DWORD value -> RZML Export = 1
 
You will have a RZML export in File - Export
 
Then in ImageModeler 3, you do File - Open (not Import).