I think they only take pictures of those sitting in front of a camera, up to two per picture...
How long are the "sculptures" there? They are images etched on metalic backgrounds on pyramidal walls. I believe we're stuck with them for a long time..
We did it the first year they had it. It was maximum of two people to a tile and they took the picture. It was very exciting when we returned two years later and found our tile. We took loads of photographs of us standing next to it, pointing.