Abstract: We use PN-triangles to improve the quality of isosurfaces extracted by marching cubes. Our contribution is a pure-GPU solution for smoothed isosurfaces, combining GPU isosurface extraction with tessellation shaders for PN-triangles. The marching cubes algorithm was first introduced to reconstruct isosurfaces of implicit functions in a uniformly sampled space. Curved PN-triangles [Vlachos et al. 2001], or PN-triangles for short, is a fast way of generating smooth surfaces using limited local geometric information, such as per-vertex positions, and normals.