Control unit, apparatus and method for producing a three-dimensional object

A device (1) for producing a three-dimensional object (2) by a layerwise solidification of the building material (13) on a cross section of the object to be produced (2) in a respective layer corresponding locations (43) comprises a coating device (12-14) for applying a layer of the building material (13) on a work plane (10), a hardening device (20) for selectively solidifying the building material (13) in the coated layer and a Gasabsaugduse (34) for exhausting gas from the device (1). The Gasabsaugduse (34) (34) is movably arranged and the apparatus (1) is formed, a movement and / or orientation of the Gasabsaugduse a function of a number of reference points (51, 53, 55a, 55b, 55c, 55d) to control or regulate.