1. A method for constructing a variogram model, which comprises: identifying a maximum direction of spatial continuity using a variogram map; displaying a rose diagram, the rose diagram comprising an edge and a plurality of vectors; rotating only the edge of the rose diagram to align the maximum direction of spatial continuity with an axis of the rose diagram; and adjusting the edge of the rose diagram using a graphical user interface until the edge of the rose diagram meets each end of each longest and shortest rose diagram vector.