Abstract: A computer implemented method is disclosed for increasing the level of detail of a polygonal surface. A first step of the method provides data in a memory of a computer (50) for representing a polygonal surface that is defined at least by a plurality of vertices, triangles and edges. Further steps of the method include providing a list of marked edges; cutting through the marked edges thereby creating new boundary vertices; applying displacements to the new boundary vertices thereby generating at least one hole in the surface, the hole being bounded by the displaced new boundary vertices; and filling the at least one hole with a forest of triangles. The step of providing data for representing the polygonal surface preferably includes a step of appending artificial vertices and triangles to the polygonal surface to fill potential boundary holes; and then subsequently removing or ignoring the artificial vertices and triangles when rendering the surface for display.