Method of controlled polymerization of a target zone in a photopolymerizable medium comprising: a processor connectable to an exposure system for illuminating the target zone in the photopolymerizable medium receiving a data representation of a 3D model of an object and using the 3D model to determine volume elements of the target zone, the photopolymerizable medium including a photo-activation compound for activating polymerization of the medium based on a first illumination field I + of a first wavelength and a photo-deactivation compound for deactivating the polymerization in the medium based on a second illumination field I _ of a second wavelength; the processor determining a target energy field E 0, the target energy field E 0 defining an energy to be absorbed by the volume elements of the target zone to achieve polymerization inside the target zone, the determining by the processor being based on a polymerization model of the polymerization process in the medium; the processor computing a direction-dependent illumination field I 0 for depositing within an exposure time t the target energy field E 0 in the volume elements of the medium, the computing of I o including using a light propagation model for an attenuating medium to compute the first illumination field I + for depositing within the exposure time t a first deposited energy E + in the volume elements for activating and maintaining polymerization and the second illumination field I _ for depositing within the exposure time t a second deposited energy E_ in the volume elements for deactivation of the polymerization; the processor controlling the exposure system based on the direction-dependent illumination field I o, the exposure including generating a plurality of direction-dependent illumination beams to deposit energy within the volume elements of the medium according to the target energy field E 0. a processor connectable to an exposure system for illuminating the target zone in the photopolymerizable medium receiving a data representation of a 3D model of an object and using the 3D model to determine volume elements of the target zone, the photopolymerizable medium including a photo-activation compound for activating polymerization of the medium based on a first illumination field I + of a first wavelength and a photo-deactivation compound for deactivating the polymerization in the medium based on a second illumination field I _ of a second wavelength; the processor determining a target energy field E 0, the target energy field E 0 defining an energy to be absorbed by the volume elements of the target zone to achieve polymerization inside the target zone, the determining by the processor being based on a polymerization model of the polymerization process in the medium; the processor computing a direction-dependent illumination field I 0 for depositing within an exposure time t the target energy field E 0 in the volume elements of the medium, the computing of I o including using a light propagation model for an attenuating medium to compute the first illumination field I + for depositing within the exposure time t a first deposited energy E + in the volume elements for activating and maintaining polymerization and the second illumination field I _ for depositing within the exposure time t a second deposited energy E_ in the volume elements for deactivation of the polymerization; the processor controlling the exposure system based on the direction-dependent illumination field I o, the exposure including generating a plurality of direction-dependent illumination beams to deposit energy within the volume elements of the medium according to the target energy field E 0.