A method and system for creating a levelling surface for use in levelling a substantially uneven ground surface, optimised for a single plane, row cropping, or dryland cropping with no rows (a surface for row cropping will typically optimise the surface with a defined water flow direction and a surface for dryland cropping will typically optimise the surface to allow water flow in any direction). Terrain data is collected, at least one constraint corresponding to desired surface characteristics is inputted, and a data transformation engine is operated, wherein the data transformation engine optimises the terrain data for at least one terrain variable, generates an optimised terrain model that substantially complies with the at least one constraint, and outputs a levelling surface. The levelling surface may be outputted to a three-dimensional controller for land-levelling machinery which could then shift the soil from the existing terrain to match the levelling surface.