1. A method for extracting capacitance information from a layout representing an integrated circuit, the method comprising: by a computer: computing capacitance information for one or more elements of at least one cell of a hierarchical database; determining whether any of the one or more elements of the at least one cell interacts with one or more elements of an other cell of the hierarchical database; combining interacting elements that are in a same hierarchy level; and adjusting capacitance information computed for a portion of the integrated circuit to compensate for the interacting elements.