An augmented-reality system includes an image capture device that obtains a captured image, an image processing unit that receives and processes the captured image to determine space configuration of a scene; a user interface that receives a position of a fiducial point inputted by a user; and a rendering device that superimposes a fiducial mark at the position of the fiducial point on the captured image. The rendering device superimposes a first computer-generated image representing a sensor at an install height above the fiducial point and on a wall of the captured image.