the device were an actual thermostat more complex control devices including multiple keys and display elements may be similarly projected and manipulated as explained earlier control devices 32 34 36 that appear in fig1 are no more than projected images on a flat wall control unit 22 typically captures a depth map also known as a 3d map or 3d image of the area of each control device and processes the depth map in order to determine that the user has contacted the wall at the location of a given device and to identify movements gestures made by the user in relation to the projected device technologies that may be used in control unit 22 to project the device images and to detect contact with the devices and manipulation of the devices by the user 39 s hand using 3d mapping are described for example in the references cited above in the background section details of a possible implementation of control unit 22 based on these technologies are described below with reference to fig2 as noted earlier one of the advantages of system 20 is that the locations and forms of control devices 32 34 36 can be changed by user 38 at will for this purpose control unit 22 may implement a touch interface with functionality similar to that offered by current touch screens for example when control unit 22 senses extended contact between the user 39 s finger and one of the control devices the control unit selects and visually highlights the device the user may then drag and drop the control device at a new location by sliding his finger along the wall of the room to the desired location control unit 22 may simultaneously project a moving image of the.