In a first step, numbering with a reference field of view at one area set first by an operator being defined as an original point is performed. In a second step, a place adjacent to a side around the reference field of view is numbered, then the measurement range is automatically moved to sequentially execute measurement at that position, presence of shape data is checked, measurement results is stored, and, presence of shape data at the numbered position is recorded on a memory device. In a third step, field of view with shape data found therein as a next reference field of view is employed, a place adjacent to a side around the reference field of view is numbered, then the measurement range is automatically moved to sequentially execute measurement at that position other than a position at which measurement has already been made or no shape data is found.