Roaming in the room:

look around – by moving the mouse while holding down the left mouse button
turn left - left arrow key or "A" key
turn right - right arrow key or "D" key
move forward / change viewpoint / image - up arrow key or "W" key
move backward / change viewpoint / image - down arrow key or "S" key
zoom in - by holding down the right mouse button (releasing the right button will stop zooming); in magnified view, hold down the left and right mouse buttons simultaneously to move around by moving the mouse