Abstract: An apparatus (100) for generating three dimensional objects comprises a first scanning carriage (102). The first scanning carriage comprises a first energy source (104) to pre-heat an area of a build surface as the first scanning carriage (102) moves over the build surface.

Abstract: A multicolor-printer has a plurality of print stations arranged to generate an image on a recording medium, and a recording medium conveyor. A plurality of similar encoding marks are associated with the conveyor. Sensor arrangements are associated with the print stations, responsive to the encoding marks. They generate signals indicating the conveyor movement with respect to the corresponding print station. An index marking is indicative of a conveyor reference position. The sensor arrangements are responsive to it, thereby providing information about the reference position with respect to the corresponding print station. The printer registers images of different print stations with each other based on the movement and reference-position information.