Map Control by Electronic Surveys

The use of electronic-distance measuring instruments to execute horizontal control surveys for mapping projects is effecting large savings in time and money and increasing the accuracy of results. After a review of the basic requirements of accuracy and distribution of horizontal control, the plan for an actual topographic mapping project is discussed. This project, the Mesa Project, New Mexico, affords an excellent example of the versatility of electronic-distance measuring equipment in difficult terrain. Use of the methods and procedures described has resulted in closures well within the limits of second-order requirements. The final parts of the paper deals with calibration of instruments on a test course, factors affecting the accuracy of electronically measured distances, and types of instruments using different media for measuring distances