An apparatus arranged to generate control data for production of a three-dimensional object comprising: an object processor to receive an object definition, the object processor being configured to generate a material volume coverage representation and an indication of structure for the three-dimensional object based on the object definition, the material volume coverage representation comprising at least one material volume coverage vector for at least one volume of the three-dimensional object, wherein, for k materials available for production of the three-dimensional object and L discrete arrangement states for said materials, the material volume coverage vector comprises L k vector components, each vector component representing an available material/ deposit state combination, and the value of each vector component indicating a probability of this material/deposit state being printed, the indication of structure indicating a structure for the at least one volume; a production controller, communicatively coupled to the object processor, to generate control data for production of the three-dimensional object, wherein the production controller is configured to: select a structure forming component from a plurality of available structure forming components for the at least one volume based on the indication of structure for the at least one volume, each structure forming component being configured to process at least a portion of the material volume coverage representation to output discrete material instruction values for volume elements at a production resolution as control data; and apply the selected structure forming component to the material volume coverage representation to generate control data for production of the three-dimensional object. an object processor to receive an object definition, the object processor being configured to generate a material volume coverage representation and an indication of structure for the three-dimensional object based on the object definition, the material volume coverage representation comprising at least one material volume coverage vector for at least one volume of the three-dimensional object, wherein, for k materials available for production of the three-dimensional object and L discrete arrangement states for said materials, the material volume coverage vector comprises L k vector components, each the material volume coverage representation comprising at least one material volume coverage vector for at least one volume of the three-dimensional object, wherein, for k materials available for production of the three-dimensional object and L discrete arrangement states for said materials, the material volume coverage vector comprises L k vector components, each vector component representing an available material/ deposit state combination, and the value of each vector component indicating a probability of this material/deposit state being printed, the indication of structure indicating a structure for the at least one volume; a production controller, communicatively coupled to the object processor, to generate control data for production of the three-dimensional object, wherein the production controller is configured to: select a structure forming component from a plurality of available structure forming components for the at least one volume based on the indication of structure for the at least one volume, each structure forming component being configured to process at least a portion of the material volume coverage representation to output discrete material instruction values for volume elements at a production resolution as control data; and apply the selected structure forming component to the material volume coverage representation to generate control data for production of the three-dimensional object. select a structure forming component from a plurality of available structure forming components for the at least one volume based on the indication of structure for the at least one volume, each structure forming component being configured to process at least a portion of the material volume coverage representation to output discrete material instruction values for volume elements at a production resolution as control data; and apply the selected structure forming component to the material volume coverage representation to generate control data for production of the three-dimensional object.