A system for tracking one or more peripherals operable by a user in a real environment, the system comprising: a camera, mounted upon the user, operable to capture images of the real environment; a light source operable to illuminate the environment for a first set of one or more image capture frames only; a feature identification unit operable to identify features in images belonging to the first set of images captured by the camera; a peripheral identification unit operable to identify the image position of one or more peripherals in one or more images belonging to a second set of images captured by the camera, wherein the camera is operable to capture images of the peripheral only when lights associated with the peripheral are illuminated, and wherein the lights associated with the peripheral are illuminated for the second set of one or more image capture frames only; and a position determining unit operable to generate first position information for the camera in the real environment in dependence upon one or more of the identified features, and to generate respective second position information for the one or more peripherals relative to the camera in dependence upon the identified image position of the one or more peripherals, wherein the first set of images and the second set of images captured by the camera are interleaved such that groups of one or more images from each set are captured in turn, wherein the position determining unit is operable to generate third position information identifying the position of the one or more peripherals in the real environment by combining the second position information corresponding to a given group of images in the second set of images with a function of the first position information corresponding to a group of images in the first set of images preceding the given group of images and the first position information corresponding to a group of images in the first set of images following the given group of images, and characterized in that the camera is operable to capture a third set of images, the third set of images being for display to a user. a camera, mounted upon the user, operable to capture images of the real environment; a light source operable to illuminate the environment for a first set of one or more image capture frames only; a feature identification unit operable to identify features in images belonging to the first set of images captured by the camera; a peripheral identification unit operable to identify the image position of one or more peripherals in one or more images belonging to a second set of images captured by the camera, wherein the camera is operable to capture images of the peripheral only when lights associated with the peripheral are illuminated, and wherein the lights associated with the peripheral are illuminated for the second set of one or more image capture frames only; and a position determining unit operable to generate first position information for the camera in the real environment in dependence upon one or more of the identified features, and to generate respective second position information for the one or more peripherals relative to the camera in dependence upon the identified image position of the one or more peripherals, wherein the first set of images and the second set of images captured by the camera are interleaved such that groups of one or more images from each set are captured in turn, wherein the position determining unit is operable to generate third position information identifying the position of the one or more peripherals in the real environment by combining the second position information corresponding to a given group of images in the second set of images with a function of the first position information corresponding to a group of images in the first set of images preceding the given group of images and the first position information corresponding to a group of images in the first set of images following the given group of images, and characterized in that the camera is operable to capture a third set of images, the third set of images being for display to a user.