1. A method of construction and storage of a hierarchical computer graphics data set, comprising the steps of: combining at least one data object of order n into at least one combined data object of order n+1, simplifying each one of said at least one combined data object of order n+1 into a simplified data object of order n+1, storing each one of said simplified data object of order n+1 storing data describing how data objects of order n were combined into said at least one combined data object of order n+1, wherein said step of simplifying combined data objects is carried out automatically by a computer implemented simplification software for at least one of said combined data object, and wherein said stored data describing how data objects were combined form part of said hierarchical computer graphics data set.