1. A method for determining a three dimensional image of an object being conveyed by a moving means through a planar beam of light the method comprising the steps of, repetitively a) capturing a two dimensional image of the object with a capturing means, the captured image comprising a scan element based on a reflection of the planar beam of light from the object and a scan element based on a reflection of the planar beam of light from at least one reflecting means, b) dividing the two dimensional image into at least two image domains, wherein one image domain comprises a reflection of the planar beam of light from the object and at least one image domain comprises a reflection of the planar beam of light from at least one reflecting means, and c) transforming the image domains into a two dimensional mutual object domain by means of a transformation procedure, while the object is being subjected to the planar beam of light and based on the plurality of the two dimensional images in the object domain a three dimensional image is defined.