Is calibration necessary to match published coordinates for surrounding marks in the ground?
A calibration is best-fitting a plane to match the curved surface of the earth with minimal distortions or errors. The plane is adjusted horizontally and vertically to fit the results of a calibration survey, and the remainder of the survey data collection is then based on this adjusted plane. For ease of calculations all surveys are performed on some type of plane based on projection parameters. Moving outside the area calibrated will require a new calibration survey (See How Should I calibrate my project below). Horizontally, yes. Even though the WISCORS network and the passive marks in the ground with NGS coordinates are both in the NAD 83 (2007) horizontal datum, there may be some very slight differences because their final positions were not adjusted simultaneously (derived independently of each other). Because both the passive marks and the WISCORS positions are based on the same national CORS network stations, any differences should be very slight. You will definitely want to ca
