A method for developing a subterranean field includes: receiving a representation of a rock surface in the subterranean field, the representation having a boundary; defining a set of grid planes over the representation; defining a plurality of core nodes at intersections of the grid planes that are within the boundary; defining core lines to connect each core node with each adjacent core node along the set of grid planes; defining a plurality of plane nodes on the grid planes where each grid plane intersects the boundary; defining plane lines to connect each plane node with each adjacent plane node along the grid planes; defining outlier nodes at each vertex of the boundary; and defining boundary lines connecting each of the plane nodes and each of the outlier nodes along the boundary. The method further includes operating equipment using at least one definition in order to develop the subterranean field.