You can use the compass to determine which way they should point. Line up the red tip to point at the south wall and a torch. Go up the stairs to the next room. Line up the red tip to point at the east wall and a torch. Take the south exit from the room.
Light crystal is by the north wall.
Line up the red tip to point at the north wall and a torch. OR The handles point in the direction of the rods. The blue light is the crystal. Once the obelisks are lined up, go back downstairs and pull the chain to smack the pillars with the hammer and create the Sun Disk . Pick up the Sun Disk and then drop through the new hole in the floor in the Light Crystal Room and follow the tunnel.