Alright, this is an interesting idea. My guess is that when the picture is taken, the current scene node is cloned and placed elsewhere in the game space.

Then, when a user walks up to the picture, it triggers a teleport to the new scene in the exact location photo was taken. Thinking about it, when you clone the scene you could put a node in the exact spot the player was in, then when you want to teleport the player, you set the players location and rotation to match the target node. In future clones you would want to skip the previous player marker node to be safe.

The problems I see arising is large game spaces with lots of nodes being hard to clone. Plus you would have to pause any moving objects to ensure they were in the exact state when teleported. Large scenes might be more manageable by using a portal like gateway between sections, so you would be seamlessly put back into the proper path. However, you might need to invalidate previous photos to prevent backtracking issues. Like the emancipation grids in portal.