At present, the sighting scale and focusing of the electronic level still need to be done visually. After manual debugging, the ruler barcode is imaged on the telescope differentiation plate for visual observation. On the other hand, it is imaged on the photoelectric sensor (also known as the detector) through the telescope's spectroscope for electronic reading. Since the barcode patterns encoded by each manufacturer's rulers are different, barcode rulers generally cannot be used interchangeably. When using a traditional level ruler for measurement, the electronic level can also be used like an ordinary automatic level. However, the measurement accuracy at this time is lower than that of electronic measurement. Especially for precision electronic levels, since there is no optical micrometer, they can be used as ordinary automatic levels. When the Anping level is used, its accuracy is even lower. Current electronic levels use three automatic electronic reading methods that are quite different in principle: 1) correlation method (Leica NA3002/3003) 2) geometric method (Zeiss DiNi10/20) 3) phase method (Topcon DL101C/102C) Compared with traditional instruments, it has the following characteristics: 1) The readings are objective. There are no errors, mis-recordings, or human reading errors. 2) High accuracy. The sight height and sight distance readings are obtained by averaging a large number of barcode marking images after processing, thus weakening the impact of ruler marking errors. Most instruments have the function of averaging multiple readings, which can weaken the influence of external conditions. Even unskilled workers can perform high-precision measurements. 3) Fast. Since the time of reporting, listening, and on-site calculations as well as the number of remeasurements caused by human errors are eliminated, the measurement time can be saved by about 1/3 compared with traditional instruments. 4) High efficiency. Just adjust the focus and press the button for automatic reading, which reduces labor intensity. Sight distance can also be automatically recorded, checked, processed, and input into an electronic computer for post-processing, which can be integrated inside and outside the industry.