Yes, I keep that center in my mind. Makes it a bit more difficult to get a good composition, but it's important. I was just talking to an archaeologist, and he is convinced the burial chambers have their 'entrance' to the east (sunrise), so in fact this composition is impossible. All sorts of things to take into account.
Just made some better entrance rocks in ZB. The vdisp map I made by working on a quite subdivided plane in mudbox, then adding a new plane and letting mudbox calculate the (world) vector displacement difference between the two. In TG I only have to import the 32-bit tiff as lineair image map and feed into vdisp shader, change some values (-Z and small displacement), getting it to work. Very easy.