I'm currently working on that but I have a small question: do you want the poster to always look towards the player, i.e around all axes? Or only follow it horizontally (without looking upwards/downwards)?
Daggerfall they stayed perpendicular to the floor they stick out from but rotate around the normal axis so as you walk around it looks like they are turning to face you. Would look wierd I think if you start climbing up a ladder and all the posters start tilting at wierd angles to the floor to stay normal to you rather than normal to the floor - sure if it is 3D rather than 2D their head might tilt up but they would never lean back to stay normal to you!. But maybe there is an application for that outside RPG pawns? The magic eye in the painting on the wall that always follows you no matter how much you try to escape by crouching down? So sounds like normal to player would be an option. not sure how normal to surface rotating in players direction will work if it is not placed normal to the surface to begin with but I would be fine with if it says facing requires normal placement so it can restrict rotation around normal axis.
Just hold F while looking at a poster to access the settings menu. You can define if they should act as regular billboards or if they should also adjust their orientation vertically.
