In automatically obtaining a height h of a collimated position by collimating a leveling rod 1 to which bar marks 11 are attached, if the height h is obtained by an image pattern of the leveling rod 1, the size of the image pattern of the leveling rod 1 must be corrected inside an electronic level 2...http://www.google.es/patents/US5887354?utm_source=gb-gplus-sharePatente US5887354 - Electronic level and leveling rod for use in electronic level
Electronic level and leveling rod for use in electronic level
