Hi Jan Willem,
The most important limitation to consider for your scenario is the maximum screen plane size supported by the Tobii REX. The REX tracks well on screen sizes up to 24″, above that tracking will be less and less good the further away from the tracker the gaze-point is. (This has to do with viewing angles and the distance between the eye tracker’s illuminators).
As you describe it, it sounds like you want to use one REX to cover a much larger physical area than 24″? Would your system work well with lower tracking accuracy outside the bounds of 24″?
If you think your system will be feasible with the above size and accuracy limitations, the next thing is how to get a non-adjacent multiple screen setup to work with the REX.
Advanced multiple screen setup with non-adjacent monitors is not supported by the EyeX Engine. The only possibility is to use the Gaze SDK.
The Gaze SDK will give you normalized gaze-points, where (0,0) is the upper left corner and (1,1) is the lower right corner of the eye tracker’s screen plane. Gaze points that fall outside the bounds of the screen plane will have values lower than 0 and/or higher than 1.
You would have to provide the REX with a screen plane defined by you, and map the normalized gaze point values to physical pixels on the respective monitor, taking into consideration the relative physical positions of the monitors. In other words, it would take some trigonometry calculations to get it working, and the screens would have to be fixed in their relative positions.
How to do a screen setup in the Gaze SDK is described in the Gaze SDK documentation.