Motion control pre-vis is a vital part of getting the day done. We wanted to pass through the glass but by nature of the process of laying track and removing it we would never know how much the mocon rig would reflect in the glass ruining our lovely reflection shot until we actually put the glass back in and the schedule and technicalities didn't allow for use to fully test and beat dailight. If it had reflected then off-course we could have done a glass replacement but we would of had to have also shot a contrary reflection pass looking out into the garden on the rig which our schedule didn't allow.

Also if we had done a completely fake glass we would of had to remove both glass panes and used a fixed arm crane and replaced the glass with an HDRI. We would of needed to remove both pieces of glass otherwise they wouldn't have matched.

I prevised this and plotted the angles to make it work. I also plotted the lights into the scene in 3D to make sure we also wouldn't see them.