To get , we ask the user to match a virtual representation of the emitter2 with the real emitter. Initially, the view in the HMD and the real object does not match. At one moment, the user freezes the image and moves the head to align them. He then validates with a “click". Since better results will be obtained when the user has to match 4 non coplanar points on the emitter, it is recommended to freeze the view in a non degenerate (axis-aligned) configuration.
We note X the coordinate of a point in the world CS and x the coordinates of this point in the image CS. We have :
, we ask the user to match a virtual 
e note X the coordinate of a point in the world CS and x the coordinates of this point in the image CS. We have :