dxf2rsd -o grass.rsd -quad2 20   grass.dxf
dxf2rsd -o ground1.rsd -quad2 20   ground1.dxf
dxf2rsd -o ground2.rsd -quad2 20  ground2.dxf
dxf2rsd -o ground3.rsd -quad2 20  ground3.dxf
dxf2rsd -o ground4.rsd -quad2 20  ground4.dxf