Optoma Geo Module BE-BWM01 - Manual (Page 5)

12. Launch the "Optoma Blending Tool" and follow the steps in the wizard.
(NB: You cannot edit the resolution / crop settings later - this will require a new
project, so be sure that you have them correct before you do the 4-corner
adjustment)
13. Select the resolution of your projectors: (NB: they must both be the same)

EX855 = XGA

EW865 = WXGA