NURBS surfaces are widely used in computer graphics, due to their great accuracy of design and reduced amount of data needed for representation. For real-time visualization, tessellation algorithms are needed, as they make use of the actual graphics hardware through the conversion of surfaces to triangle meshes. The existent algorithms for tessellation are only partially adaptive because the tessellation inside each part of the surface is uniform (non adaptive). We propose an algorithm that generates a mesh of triangles from a NURBS representation of the scene in a fully adaptive way, that is, the resolution is locally selected in such a way that the number of triangles to be processed is minimized without reducing the quality of the nal image.