The walls are NOT holographic, for the last time! Everyone who thinks they are holographs, go play through the Great Salt Lake section of the game again. It's made painfully obvious that the wall consists of multiple SOLID hexagons(or some polygon, can't remember for sure how many sides) which can each appear as whatever Esthar wants it to look like.
I mean, the party even climbs up a ladder which is attached to this wall. That alone disproves the notion that the wall is holographic.