The terrain where the point is located is higher, and it is better to be on the commanding height, so as to facilitate the transmission of data signals.(3) It is convenient to charge near the point to ensure the special needs of continuous power consumption of the reference station.(4) The location of the point relative to the area to be measured is moderate, which is conducive to the coverage of the operation radius.3.7.2 GPS-RTK operation mode under different coordinate systemsGPS-RTK survey is mainly to make full use of its two functions of fast positioning and real-time lofting. In most cases, only point lofting really needs real-time measurement, and fast positioning does not always need real-time coordinates, that is to say, point coordinates can be provided through post-processing. Therefore, in terms of operation mode, we can optimize and design the operation mode of GPS-RTK survey according to the urgency of the demand for survey results of the project, so as to shorten the field observation time as much as possible and really improve the operation efficiency.