Breaklines in Coons surfaces over triangles for the use in terrain modelling

This paper introduces a modification to the triangular Coons patch method allowing the consideration and modelling of breaklines. The method leaves the boundary curves representing breaklines unchanged but alters the curves leading to breakline vertices. In order to abandon first-order continuity, it introduces left- and right-side surface normals at the breakline vertices and uses a special configuration of the cross-boundary derivatives. The results are visually and quantitatively assessed.