1. In a physics-based visualization system having a plurality of data objects, a method for computing forces on said data objects, comprising: determining first forces exerted on a data object by other data objects in said plurality, said first forces calculated without considering similarity between data objects; determining second forces exerted on said data object by a portion of said other data objects, each data object in said portion having a degree of similarity to said data object, said second forces calculated considering similarity between data objects; and adjusting said first forces using said second forces to determine a net force on said data object, said net force determined without having to consider similarity between all data objects in said plurality.