A system and method for summarizing data corresponding to properties of interest on an unstructured grid that includes active cells and inactive cells on an output surface. An exemplary method comprises identifying an aggregation direction through a region of interest of the unstructured grid and identifying at least one active cell along the aggregation direction. The exemplary method comprises 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 at least one property of interest for the at least one active cell. The exemplary method further comprises 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.