1. A computer implemented method for providing data describing a physical structure, the method comprising: defining an unstructured grid that corresponds to a three-dimensional physical structure, the unstructured grid comprising data representative of a property of interest, and the unstructured grid is a completely unstructured grid that does not employ an index domain to define the unstructured grid; defining at least one filter object and a selection criterion; selecting a portion of the unstructured grid data that meets the selection criterion relative to the filter object; and using a computer to create a visualization of the selected portion of the unstructured grid.