The present invention describes a device for surveying a surface (104) in a real world coordinate system (111). The device comprises a pattern projecting unit (101) adapted for projecting a predefined pattern (105) onto the surface (104), an optical measurement system (102) adapted for determining positional and image data of a projected pattern (106) on the surface (104), wherein the positional and image data are indicative of the predefined pattern (105) in a measuring coordinate system (112), and a processing unit (103) adapted for determining transformation data based on the predefined pattern (105) and the determined positional and image data of the projected pattern (106). The transformation data allow a transformation between the real world coordinate system (111) and the measuring coordinate system (112) to thereby survey the surface (104).