A method for producing hydrocarbons from an oil and/or gas field using data corresponding to a property of interest of the oil and/or gas field, the method comprising: identifying an aggregation direction through a region of interest of an unstructured grid that embodies data corresponding to at least one property of interest, the unstructured grid including a plurality of active cells and a plurality of inactive cells; identifying at least one active cell along the aggregation direction; summarizing data corresponding to the at least one property of interest for the at least one active cell; constructing an output surface based on model topologies represented by the unstructured grid or an intersection of a surface and the unstructured grid; assigning an aggregated value for the at least one property of interest to a face of the output surface on a line along the aggregation direction based at least in part on the data corresponding to the property of interest for the at least one active cell; identifying at least one data hole in the output surface where at least one aggregation has no corresponding face on the output surface, or where at least one output face is not assigned an aggregated value because it is not on the line along the aggregation direction; filling the at least one data hole by identifying at least one face associated with an inactive cell on the line along the aggregation direction and assigning it an aggregated value or by identifying at least one face on the output surface that is not assigned an aggregated value and assigning it an aggregated value corresponding to another face in the cell containing the at least one face that is not assigned an aggregated value; producing a data map that comprises the values for the at least one property of interest on the output surface; wherein the above steps are carried out by a computer system; and further extracting hydrocarbons from the oil and/or gas field using the data map. identifying an aggregation direction through a region of interest of an unstructured grid that embodies data corresponding to at least one property of interest, the unstructured grid including a plurality of active cells and a plurality of inactive cells; identifying at least one active cell along the aggregation direction; summarizing data corresponding to the at least one property of interest for the at least one active cell; constructing an output surface based on model topologies represented by the unstructured grid or an intersection of a surface and the unstructured grid; assigning an aggregated value for the at least one property of interest to a face of the output surface on a line along the aggregation direction based at least in part on the data corresponding to the property of interest for the at least one active cell; identifying at least one data hole in the output surface where at least one aggregation has no corresponding face on the output surface, or where at least one output face is not assigned an aggregated value because it is not on the line along the aggregation direction; filling the at least one data hole by identifying at least one face associated with an inactive cell on the line along the aggregation direction and assigning it an aggregated value or by identifying at least one face on the output surface that is not assigned an aggregated value and assigning it an aggregated value corresponding to another face in the cell containing the at least one face that is not assigned an aggregated value; producing a data map that comprises the values for the at least one property of interest on the output surface; wherein the above steps are carried out by a computer system; and further extracting hydrocarbons from the oil and/or gas field using the data map.