A register file design having an asymmetric bit line driver is provided. There is provided a geospatial information creating system for extracting a footprint of a house from an aerial photograph, comprising a processor for executing a program, a memory for storing data required for executing the program, and a storage unit for storing the aerial photograph. The screw actuator being at least partly mounted within the sleeve 25 and being arranged to bear against a portion of the sleeve assembly to transmit axial thrust to the sleeve assembly, and the sleeve assembly cooperating with an abutment to transmit the axial thrust to the abutment.