1. A method for identifying advantageous locations for placement of two or more entry ports for performing an operation within a defined volume having a closed surface, the method comprising: preparing a representation of the defined volume from a set of acquired data; defining at least one target area within the defined volume; and determining from the representation and the target area the advantageous locations for placement of the two or more entry ports for performing the operation, the advantageous locations being disposed on the closed surface of the defined volume.